Acquired Poison Immunity

You won't be wanting that, then?

"Mithridatism, it's called. Isn't that a funny name? The process of eating poison to build up immunity. So long as I don't die from it, I'll be harder to kill."

— Jude Duarte, The Cruel Prince

In short, this trope references the development of immunity to a particular drug or poison by taking small doses for a long time.

Here's a typical scenario: The hero has finally appeared at his confrontation with the Big Bad, who's seated at his ridiculously long table, just about to take his evening meal. "There's no reason to be uncivil," the villain says. Would the hero like some wine? The hero takes a drink and immediately starts choking. The villain laughs — that fool, the hero, should have known that the villain would poison the wine with the dreaded juice of the Ultramurder fruit!

But what's this? The hero's standing back up! "I knew you'd poison the wine with the dreaded juice of the Ultramurder fruit. That's why I've spent years eating small pieces of Ultramurder fruit, to develop an immunity to the poison!" The hero then kicks the villain's tail.

In some cases, the poison builds up and actually turns the poison-proof character into a Poisonous Person.

This can be Truth in Television, or not, depending on the poison in question. For some (chiefly organic) poisons, the body produces antibodies to clear them from the system; so, with repeated exposure to small amounts, you can build up a level of circulating antibody that grants immunity to a typical dose. This is the principle upon which real-life vaccines are based, injecting a deactivated variant of the poison so the body can develop antibodies that will work on the active variant. In the past ages, the few metallic poisons known were rare and expensive; therefore most poisons were plant-based alkaloids.

Should a non-organic poison enter the equation however, this trope becomes a lot less realistic. There are plenty of other poisons that don't get cleared from the system and simply build up in your tissues until you reach a lethal dose. This includes nearly all heavy metals to which modern civilians and industrial workers are exposed, such as compounds of lead, radium, mercury and cadmium; it's why metalworkers in the old days could end up with permanent skin discolorations, and why metalworkers in these days typically have full protective gear.

The official term for immunizing oneself to poison this way is Mithridatism, after a king who made use of the effect. It backfired when he was defeated and tried to commit suicide; his immunity to poison worked so well that he ended up needing to hire a mercenary to run him through.

Could be considered a sub-trope of Adaptive Ability. A particularly Crazy-Prepared person may be immune to several — or even all — poisons via this method, though again it's important to note that in real life, not all poisons can be defended from in this manner. This trope is often key to the survival of someone who is pulling a Self-Poisoning Gambit.

See also and closely related to Removed Achilles' Heel, which is when a character gradually gains immunity to an inherent weakness by repeatedly exposing themselves to it. Compare Radiation-Immune Mutants, for people and creatures who become immune to what changed them.

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Examples:

Anime & Manga

• In Akuma no Riddle, Haru Ichinose has gone through so many surgeries that she has started to become resistant to sleep-inducing drugs. Even if she does get affected, she wakes up a lot faster than a regular person would.
• In Apothecarius Argentum, Argent was fed a number of poisons at a young age so he could be sold as a food taster/assassin. As a side effect, they also turned his blood into some kind of killer acid, and just touching him is enough to make his love interest, the princess faint.
• The main character, Maomao, from The Apothecary Diaries has built up a level of immunity to most poisons due to her frequent experimentations with various poisons. This comes in handy when she becomes a poison taster, but unlike the other poison tasters she actually looks forward to a poisoned meal.
• Subverted in Bleach. During Mayuri's fight with Szayelaporro, as his Bankai's poisonous gases seep over to the injured Ishida and Renji, Ishida initially believes that unlike Renji, he will be safe from the poison, as he was poisoned before in his previous battle with Mayuri. Ishida then shows symptoms of poisoning, and Mayuri mocks the idea that someone could become immune to his poison, saying that it is constantly adapting itself.
  • Earlier, during the Bount arc, Sui-Feng is poisoned by one of their dolls. While this poison does affect her, she has built up an immunity to her Zanpakuto's and several others. If she ever comes across a poison she isn't immune to, she stabs herself with her own poison which eats the strange poison without affecting her.
• In Brave10, this is a common part of ninja training as demonstrated by Anastasia, Saizo and Sasuke during the Goemon gang's Knockout Gas attack. They aren't immune to every kind of poison and even the ones they are cause them to become weak the longer their exposure is, but the three proper Ninja of the team are all able to keep fighting even when the rest of the team is completely out because ninja are Crazy-Prepared.
• In Dokuhime little girls are purchased for the purpose of bringing them up to be Poison Princesses and exposed from the time they're in their cradles to poison in order to build up immunity. Many don't make it, the successes are trained to be assassins whose very touch is deadly. They have to keep ingesting poison to function properly.
• Fairy Tail:
  • In a similar vein to the Pokémon example below, the heroes face an enemy that uses colored magical confetti to produce various elemental effects. When said enemy attempts to use yellow lightning-producing confetti on Mirajane, the latter laughs, as (having had Laxus for a guildmate during his entire jerkass phase) she's been zapped enough times that the yellow confetti can't produce enough voltage to faze her.
  • The demons of Tartaros capture Mirajane and inject her with demon blood, intending to convert her into a minion. However, the demons didn't know that Mirajane specializes in Satan Soul Takeover magic, where she converts her body into a demon and has complete control of herself. As a result, the demon blood fails to control her and increases her power enough to break her bonds and escape.
• Holy Corpse Rising: Amala's parents died and her older brother abused her and kept her prisoner, feeding her poisoned food in an attempt to kill her. Determined to survive, she ate the food little by little, eventually developed an immunity to the poison, and grew strong enough to kill her brother. In the present, Mylitta's poisons only affect her for about a minute.
• Killua from Hunter × Hunter is immune to virtually all forms of poison due to his family's Training from Hell, and is seen happily downing five cans of laxative-laced juice before the Hunter Exam starts. He's also been subjected to enough Electric Torture that electric weapons only cause a slight tingle, and he later develops Shock and Awe powers.
• Downplayed in Little Witch Academia (2017). For Akko, getting repeatedly poisoned by Sucy finally pays off when it allows her to briefly resist the bites of a couple of venomous snakes controlled by Lady Daryl Cavendish, but she soon collapses and requires urgent medical attention.
• In Mission: Yozakura Family, the titular spy family doses their meals with poison on a regular basis to build up an immunity as part of their Training from Hell. It proves essential when facing enemies with poisoned weapons in the field and saves Taiyo's life on several occasions (at least after getting over the initial bouts of diarrhea).
• While it never comes up as a major plot point, it's mentioned a few times in Musuko ga Kawaikute Shikataganai Mazoku no Hahaoya that demons do produce antibodies when exposed to anti-demonization gas and can theoretically build up a resistance, though no one is ever seen with an outright immunity. However, Lorem does have an incredibly high resistance to Zeke's poison (which the gas was derived from) thanks to passively breathing the stuff in for the several years they were living together in secret, to the point that she could generate enough heat to keep herself warm in the middle of a blizzard around the time of Gospel's conception.
• In Ninja Scroll, Kagero's body absorbs toxins instead of processing them. It makes her ideal for working as her master's food taster, but it's also made her bodily fluids highly toxic, which is good for assassination — not so much for potential love interests. However, the kiss she and Jubei share just before she dies is implied to be enough to counteract the poison in his body.
• Assassin Shao Li from Noir kills using poisoned fingernail polish and inflicting a small nick on her victim, and in one scene she kills a man using incense that contains a poison she's built up an immunity to and remarks as he's choking on the ground that to her it just smells pleasant.
• One Piece:
  • Played for Laughs with Magellan, whose Devil Fruit powers allow him to manipulate and create all kinds of poisons; this naturally made him immune to poisons himself, meaning he enjoys eating poisoned meals. Unfortunately for him, his fruit didn't give him the power to digest poisons on top of his immunity, so his dining habits leave him stuck on the toilet for ten hours a day.
  • Less for laughs and more for awesome after the Time Skip, when Luffy's clash with Magellan gives him immunity to a crapload of poisons. As if he hadn't taken enough levels in badass already... Even then, his antibodies still have limits; a strong enough poison (as in, one that would cause instant death in a normal person) will still make him extremely sick and eventually kill him without treatment.
  • Sanji's estranged sister Vinsmoke "Poison Pink" Reiju has this as well. At some point, Luffy is very sick after being given a very powerful poison, but she went up to him and gave him a Kiss of Life to absorb it and heal him. She has no physical side-effects afterwards.
• In a later chapter of Onidere, it's revealed that Tadashi has been rendered completely immune to all forms of poison due to constantly eating his girlfriend's cooking.
• Pokémon: The Series:
  • Ash has gotten fried by Pikachu so mch that he's built up a near-total immunity to electric shocks, surviving jolts that were outright exploding whatever they hit in a later episode. And on a couple occasions Team Rocket have also shrugged off electric shocks after being zapped by Pikachu so many times, with Meowth even making use of his Pikachu-induced shockproofing once.
  • AJ's Sandshrew has Acquired Water Immunity. As Ground-types, Sandshrew are typically weak to water. This one can swim.
• Zen of Snow White with the Red Hair, being a prince and thus having a good chance of being poisoned, spent an extended amount of time becoming immune to many different poisons.
• Yor Forger from Spy X Family alongside other contract killers, built up a high tolerance against poisons. This gets Played for Laughs in a bonus chapter where she gets Shot in the Ass on a hit job and a surviving member of the terrorist group she slaughtered on said job, who while posing as a waiter, gave her a blowfish poison martini. This actually helps her since the poison took the pain away from the wound in her behind.
• Most of the Gourmet Hunters in Toriko have resistance to various poisons due to incidental or deliberate exposure. Coco is an extreme example, having been exposed to so many toxins that he's able to synthesize them within his body, and on the rare occasion that he's hit with a poison that he ISN'T immune to, he can adjust his immune system within seconds.
  • Grinpatch, a member of the Gourmet Corps, is even better than Coco. His entire body is structured like a filtration system that allows him to neutralize any poison. When he was injected with a poison that adapts itself against the victim's immune system, it just ended up being endlessly shuffled between Grinpatch's various "filters" without producing any actual effect.
• To Your Eternity: The character Tonari has developed an immunity to nearly all poisons as a result of exposure therapy over the course of 40 years. She does this in order to make her body into a useful vessel for the main character Fushi.

Comic Books

• Batman:
  • One issue revealed that the title character regularly devises antidotes and methods of controlled exposure to Scarecrow's fear gas. However, every time Scarecrow attacks Batman with gas, he changes the formula afterwards so that immunizing against the previous has no effect. Batman does it simply on the off chance that Scarecrow didn't change it this one time. In Batman R.I.P., Batman reveals that he is immune to many toxins and poisons, and carries antidotes for all the ones he isn't immune to.
  • On the topic of Dr. Crane, apparently he's gassed himself so often he's become unable to fear anything...except Batman.
  • The Joker has built up immunity to his trademark poison to the point that mosquitoes writhe in pain after sucking his tainted blood.
    • Played for Laughs in Batman & Captain America, where the Joker and the Red Skull discover that their signature poisons are so alike that each is immune to the effects of the other.
    • Same deal with Harley; in her own title, she once tried to bluff Batman into thinking she was committing suicide by drinking it. (Didn't work; he knew she was immune to it.)
  • Also, the Joker is apparently immune to Scarecrow's fear gas, as one comic has them team up before Scarecrow sprays the Joker with his fear gas, which only resulted in the Joker smashing Scarecrow over the head with a chair.
    • In one instance, the fear gas caused the Joker to laugh uncontrollably.
    • Since it's the Joker we're talking about, it's less likely that it's a result of acquired immunity and more that he's simply too crazy to be afraid.
  • It's often established that Joker is immune to many toxins including his own Joker Venom due to years of dedicated substance abuse.
  • Harley Quinn is immune to Poison Ivy's poisons owing to their time as sexual partners. In the animated series, this is Handwaved by having Ivy just give her a vaccine against them.
• Black Moon Chronicles: The master of the Thieves' Guild that Pilou grew up in kept the other criminals in line by putting poison in their food and providing an anti-toxin at the end of every day if they had fulfilled their quota. Pilou starts to take a small portion of the poison every day to build up an immunity so he can one day escape.
• Blade: Blade once fought with Draconis, a vampire priest that developed immunity to all traditional weaknesses like holy symbols and sunlight with small gradual exposures to it, in addition to his unshakable faith turning him into a "Holy Vampire".
• The Boys: The Russian mob attempts to kill the team with poison but while most of them were knocked out but kept alive by the Compound V in their system, Hughie and Love Sausage are completely unaffected due to them drinking Love Sausage's brake fluid cocktail which happened to build up their tolerance for poison.
• Harley Quinn: In one issue, Harley rapidly throws off an attempt by Dr. Hugo Strange to drug her and explains to him that it's a bit silly to try to poison someone who's had long-term sexual relationships with both the Joker and Ivy.
• It's actually a somewhat common martial arts technique in the comics Jademan translated for US release in the '80s and '90s. Indeed, most poison immune characters could actually manipulate their immunity so they could cure someone else's poison by drawing a bit of their own blood and feeding it to them.
• In the comic New X-Men, Laurie Collins aka Wallflower is the daughter of Sean Garrison, a mutant with extremely powerful pheromone production and control, who had Laurie's mother Gail in his thrall until Laurie was conceived. Because Laurie inherited her father's mutation, carrying her made her mother immune to Sean's pheromones and enabled her to break free of his control.
• Red Robin's opponents the Council of Spiders have a couple of poison users who are immune to their own poisons.
• Spider-Man: Spider-Man seems to be developing an immunity to the gas used by the Green Goblin to nullify his Spider-Sense. Originally, the stuff rendered him unconscious and would make him unable to use the power for several days. Most recently, when the Hobgoblin used it in the "Revenge of the Sinister Six" story, he was able to stay conscious and recover in little over one day.
  • In Spider-Island, Mary-Jane is one of the last people to be infected with Spider Flu. Reed Richards theorizes that the delay was due to her having been sleeping with Peter Parker for years.
• Superboy: In issue #58, Superboy deliberately exposes himself to pieces of kryptonite, to build up an immunity to those particular pieces, so he can later use them against Kryptonian criminals without being affected himself.
• Superman:
  • Nearly every depiction of one of his future incarnations has them demonstrate considerably more tolerance to the effects of Kryptonite, implying that this trope is in effect. Particularly if the story has them paired up with his counterpart from the present day, where Future!Supes will often shrug it off while the Present!Supes is vastly weakened. This depends on the incarnation, however; some continuities justify his resistance with other sources, such as a vastly increased store of solar energy.
  • And even as early as the first year of comics, it was established that Superman is naturally immune to many poisons simply because they weren't compatible with Kryptonian biology.
• The Tick: Spoofed with a minor character who claims to have been building up an immunity to bullets this way. The character was an expy of Dick Tracy, who has been shot an absurd number of times over the decades.
• Usagi Yojimbo: Chizu takes a small dose of poison every day for this reason.
• Venom: The Venom symbiote has been stated to have become increasingly resilient to flames and sonics through repeated exposure. How much more resilient it's become depends on the writer.
• Wolverine: The assassin Reiko invoke this trope with blowfish toxin, which Jubilee learns while dodging attacks.
• Electric Warriors: The series is set somewhere in the post-apocalyptic world of Kamandi where humanity has somewhat recovered and is coexisting with uplifted animals. The Earth has settled into a galactic community that avoids war over scarce resources through a hunger games kind of ritual where they empower champions to battle on their civilization's behalf. The food stocks from Earth are stuff known to be highly toxic like Gingold or the Joker's laughing fish.
• Teen Titans: Cheshire is a Master Poisoner who has made herself immune to countless types of toxins and poisons in this fashion. In one Birds of Prey storyline, shot took down Lady Shiva by simply flooding the room with an odorless and paralyzing toxin. Shiva soon fell to the floor while Cheshire herself was immune to the effects.
• One version of Cobra Commander was given treatments against cobra and other snake venom. (This particular version was previously Baron Ironblood, the main villain of the European Joe equivalent, Action Force. When Hasbro bought out Palitoy, they proceeded to bring in various characters and concepts from the US GI Joe line, resulting in Ironblood becoming fed up with the Red Shadows' failures and intentionally leaking info about their bases, while he went to Southeast Asia to form this continuity's version of Cobra.)

Comic Strips

• Spoofed in the Newspaper Comic Close To Home, where a golfer subjects himself to gradually stronger shocks of electricity to build immunity to lightning strikes.
• Get Fuzzy. In the strip for May 18th, 2013, Bucky says that he consumed two spiders per day for the last four years to build up an immunity to poison. When Satchel points out that the spiders in their house aren't poisonous, Bucky doesn't feel so good.

Fan Works

• Aeon Entelechy Evangelion combines this with Conditioned to Accept Horror in Asuka's EVA pilot training, which included controlled desensitizing to anything that causes sanity loss.
• In the Italian version of Battle Fantasia Project, fairies suffer brain damage when exposed to iron for too long, but Bloom became immune to iron poisoning by growing up on Earth, where iron is used for everything, since before developing her powers and thus the vulnerability.
• The End of the World (FernWithy): Twenty-five years of hard drinking's effect on Haymitch's liver (plus the regular detox pills he takes to try to counter that) make it hard to poison him in a way that will look like a natural death from drinking too much, as both Snow and Coin discover.
• Being a trained Sheikah, Impa notes that she is immune to many toxins in Blind Courage.
• In Fate Ingens Cor, Assassin picks up one of Archer's missed poisoned arrows and stabs herself. The poison weakens her a bit, but she quickly recovers and gloats that the poison will never affect her again.
• In Glitter Force: Into the Glitterverse, the Smile and Doki Doki Pretty Cure teams are immune to the Glitter Force infection, due to having been infected in the past.
• In My Hero Academia: Unchained Predator, the Slayer is heavily resistant to all forms of gas, from sleeping gas to extremely deadly nerve agents due to him surviving in Hell for literal eons. Not that the heroes and villains don't know, but in the end, Midnight's trick failed to even make the man dizzy.
• Not the intended use (Zantetsuken Reverse): One of the souls that Soma stole allows him to eat rotten food. He uses it to keep the fridge clean and make bets with his - clueless at the point - roommates. Unfortunately, it can't do anything about his nut allergy because nuts are not inherently poisonous.
• In Origins, a Mass Effect/Star Wars/Borderlands/Halo Massive Multiplayer Crossover, Samantha Shepard has to turn this off in order to get drunk since she's now more machine than woman. Mordin Solis even has to adjust the power in her cybernetic legs to let her dance!
• The Rigel Black Chronicles: Harry doesn't exactly build up immunity to poisons, but in preparation for the Fifth Triwizard Task, and under Professor Snape's careful supervision, she trains herself to flush them out of her system with magic, after allowing them to progress to varying degrees. The Draught of Delirium still leaves her confused, weak, and struggling, partly because her dose was tampered with, but she handles it well enough that she wins the Task.
• In Ruby and Nora Oobleck thinks he has this trope. While one tranquilizer doesn’t knock him out, a heck of a lot more do.
• in The Hunger Games short story Secrets, a companion piece to "The Victors Project" it's mentioned that using this trope was the only thing that kept Luster Lancaster (leader of District One's career victors in the author's previous fanfics) from being killed by one of his own victors (who was prostituted by Snow at Luster's suggestion) several times during the fifth decade of the games.
• In Ultra Fast Pony, Rarity is allergic to water. In "Copywrong", she tries to build up immunity by soaking in a pool. Twilight points out that her allergic reaction seems to be getting worse, not better.
• The titular badger in The Urthblood Saga, among his other powers, has built up an immunity to all but the strongest poisons from this method. One poor ferret who tried to poison him and take over his army learned this the hard way...
• In Yu Yu Hakusho Abridged, it is implied that this is how Suzaku learned to control lightning.

Films — Animation

• Clownfish Marlin and Nemo from Finding Nemo have built up a resistance to venom stings from living in a sea anemone. This ends up coming in handy when Marlin and Dory end up in a swarm of jellyfish.
  Dory: Hey, why didn't it^note  (the little Jellyfish, AKA "Squishy") sting you?
  Marlin: It did. It's just... I-I live in this anemone, I'm used to these kind of things.

Films — Live-Action

• In Woody Allen's Bananas, Gen. Vargas has a servant on hand to taste his meals in case they are poisoned. One meal does turn out to be poisoned, but the General eats it, anyway, claiming that he's been poisoned so many times to have developed immunity.
• In the short film The Bloody Olive, the female lead explains to a bystander that she was vaccinated against all types of poisons, which rendered the villain's poison dart ineffective.
• In the 2008 movie Get Smart, 99 sprays Max with knockout gas. Max says that he developed an immunity to it, then passes out while cursing, "That's new stuff."
• IO. Sam has a line of scar lumps on her midriff from where she keeps dabbing her skin with tiny doses of toxin in the hope of adapting to Earth's changed atmosphere. When Micah tries to force her to leave the planet with him on the last shuttle, she removes her gasmask to prove she has indeed adapted. Fortunately she's right.
• Pat Morita's character Hashimoto in King Cobra (1999) is a snake handler who regularly injects himself with doses of snake venom to develop immunity. He's able to shrug off getting bitten by the giant snake once, but after getting bitten a few more times, he weakens and dies.
• The King's Man: The attempt to poison Rasputin failing is attributed to him consuming a small amount of poison every morning. Though he also vomits up the poisoned cake.
• The Princess Bride: The Man In Black challenges Vizzini to drink from two cups, one of which has been poisoned with iocaine. After they both drink and Vizzini dies, the Man in Black reveals that he poisoned both cups because he'd spent the last few years developing an immunity to iocaine.
• In the third Riddick movie, Riddick has to get through a narrow pass to get out of the desert into the fertile grasslands beyond. The pass houses a muddy pool with a poisonous scorpion creature that paralyzes its prey. He captures a younger, smaller creature, and extracts the poison. He tests it on a young desert dog first, then injects himself with small doses until he's built up an immunity.
• In Thank You for Smoking, terrorists try to kill the main character by covering him in nicotine patches, which would overwhelm any normal person, and leaving him naked on the lap of the Lincoln Memorial. He survives and recovers fairly quickly because he'd been chain smoking for years and had built up a superhuman tolerance to nicotine. Unfortunately (fortunately?) it also means he can never smoke again.
• Under Siege 2: Dark Territory has a thug who has been pepper-sprayed so many times, all it does is clear out his sinuses. And then he proves it by using it as a breath freshener.
• In Your Highness, The Wise Wizard, Fabious, and Thadeous smoke herbs together. The Wise Wizard and Fabious get stoned immediately and suffer hallucinations, but Thadeous (who regularly smokes pot) is unaffected.

Jokes

• Shoot yourself with lower-caliber bullets to build up an immunity to higher ones.

Literature

• 1% Lifesteal: The "Hundred Wet Hells" body tempering technique works by making every particle of water in the user's body turn against them. The first time Freddy uses it, he immediately passes out, presumably from something in his brain being affected. However, the more the user becomes accustomed to the technique, the more their body becomes resilient to the effects, with the result that they can largely ignore all kinds of pain, disorientation, nausea, etc. Freddy later empowers it with the essence of Turbulence, escalating its effects for greater rewards.
• In BOFURI: I Don't Want to Get Hurt, so I'll Max Out My Defense (seen on the Video Examples page for this trope), the main character Maple uses this to maximize her skill (via using potions when she's about to die) to develop a higher level of immunity and to have a chance to defeat a poison dragon.
• One 1632 short story centers around a poisoning that was originally suspected to be a murder until it was discovered to be an accidental suicide. The dead man had been dosing himself with arsenic regularly in an attempt to build up an immunity. Unfortunately, his regular supplier had been selling him adulterated drugs, so his immunity wasn't built up anywhere near as much as he thought. After buying a new supply from a different chemist, who sold him pure arsenic, he took what he thought was the appropriate dosage for his regimen, which was based on the weaker drugs of his first supplier. The massive dose of pure arsenic overpowered his limited immunity and killed him.
• The eponymous heroine of the Angelique novels (set during King Louis XIV's reign) survives an assassination attempt when the killers force her to drink a cup of poison. Unbeknownst to them, she had already taken for some years a pill each day, filled with minute amounts of the most common poisons of that age. This got played realistically, as despite the acquired tolerance and the fact she throws up just after the assassins leave, she still got very sick for the next few days and barely survived.
• In Ave Xia Rem Y Liu Jin's training under Old Jiang starts with Jiang feeding him a fruit that leaves Jin paralyzed until he is able to use Ki Manipulation to purge the poison. After several months of learning how to deal with progressively more potent toxins, the next step of his training is a test by the Nine-Headed Snake God that causes his body to constantly produce poison that he needs to neutralize for three years. By the end of this trial Jin is able to shrug off poisons that would kill cultivators vastly above him in Power Levels and neutralize almost anything that attempts to affect his body.
• In Aztec by Gary Jennings, the travelers all take their snakebite prevention medicine, which involves being injected with venom from a tooth of each kind of poisonous snake. The doctor who performs the procedure advises Mixtli that his bite will now be venomous; when he finds out it's not, he assumes he is not immune to snakebite.
• Poisoning is the de facto assassination method of the Nyissans in the Belgariad. So much so that any government official who lives for very long (case in point: Sadi) has not only long since acquired immunity to some poisons, but is trained to recognize much more, and doses himself with antidotes frequently, just in case. It's explicitly noted that the poisons taste much better than the antidotes. As an interesting side effect, Sadi is also Unaffected by Spice, able to finish off a meal that had Durnik break out swearing.
• In Best Served Cold by Joe Abercrombie, poison-master Morveer keeps himself resistant to many of his own poisons by regularly consuming them.
• Beware of Chicken: Lu Ri once encountered a senior disciple capable of manifesting her Intent as an oppressive aura. He wasn't the target at the time, but he seized on the opportunity, requesting that she give him the opportunity to experience it and learn to cope. It's a hellish month for him afterward, as she unleashes it on him at random, but it works, training him to keep his composure in the face of pressure that could crush those of lesser spirit, which equips him well to deal with highly displeased sect elders after Jin Rou's departure.
• In the Dashiell Hammett Continental Op short story "Fly Paper" (1929) a woman wants to poison her abusive boyfriend but is afraid he'll be suspicious if she gives him something without drinking it herself. After reading The Count of Monte Cristo she takes small doses of arsenic (extracted from flypaper) to build up an immunity, but instead fatally poisons herself. In discussing the case afterward the detectives reveal that the book is wrong; while some people have a natural resistance to arsenic, it's not possible to build up immunity through controlled exposure. The poison of choice in The Count of Monte Cristo is in fact Brucine, and is subject to Mithridatism.
• In The Count of Monte Cristo, old Monsieur Noirtier survives a murder attempt using poison because he has been taking a medicine that contains the same compound, and has built up a resistance to it. Realizing that his granddaughter and heir Valentine is also a target, he starts giving her small doses of his medicine; this saves her life when the poisoner has a go at her. The poisoner later tries again using a different poison, but by then Valentine's Love Interest Maximilien has called in his friend the Count of Monte Cristo, who saves the day in his own inimitable style.
• In Agatha Christie's Curtain, Hercule Poirot drugs the murderer using his own sleeping pills, which he has been taking for many years. He uses the same gambit as Westley does in The Princess Bride, poisoning both cups while implying that only one cup is poisoned.
• In John Wyndham's The Day of the Triffids, the narrator is only alive at the beginning because a career of working with Triffids has led to him building up enough resistance to survive the sting that put him in hospital. Simon Clark's sequel, The Night of the Triffids, develops the idea, with a way being discovered for people to deliberately cultivate an immunity, offering a way in which humanity can finally take the world back from the Triffids.
• Downplayed in "Different Kinds of Darkness" by David Langford, wherein "basilisks" are printable images that short out the human brain when viewed. A group of schoolchildren makes an endurance contest out of staring at a weak version they call "the Trembler", unknowingly building up a resistance to the basilisk effect; when a truly deadly basilisk is left in the school, a member is able to destroy it and only passes out from the sight.
• Discworld:
  • A novel or two mentions a food-taster who has ingested so many poisons that he's not only immune to them but can recognize them by taste (very handy). He can also tarnish silver by breathing on it (not so handy). He reputedly eats a toad a day to stay in practice.
  • The vampires in Carpe Jugulum have also built up a resistance to garlic, sunlight, holy water, vampiric OCD, and holy symbols by this method. It backfires, sort of. When they lose the immunity, they realize they're surrounded by the shapes of holy symbols they wouldn't recognize if they hadn't been shown so many different ones becoming immune in the first place.
  • Played with in Mort. The first King that Mort sees die asks Death how he was killed. Death explained it was by a crossbow. The king laughed and said "And here I have been making myself immune to all of these poisons. There's no immunity to cold steel, eh?"
• The Disgaea novels gives an explanation as to why Laharl survived being poisoned by Etna in the game, the reason was that his crazy aunt Yasurl gave him the same poison when he was little and in her care.
• In Dreamsnake, Healer training involves becoming immune to several types of snake venom, since they use genetically engineered snakes to heal. They still get sick if one of their snakes bites them, but they won't die. However, it has some nasty side effects, such as making most of them sterile (most of their children are adopted) and giving Snake premature arthritis.
• The Dresden Files: Harry Dresden does a mental version of this in Turn Coat, bludgeoning his mind with the memory of every horrible, nasty thing he's ever seen and experienced in order to desensitize himself and recover his stability after viewing The Naagloshi with his Sight.
• Harnrim Starangh, a Red Wizard from Elminster's Daughter. "It had taken two years of retching weakness to build up a resistance to killing doses of staeradder", but being able to use a fast-acting poison freely was worth it since his most dangerous foes were other wizards whom he couldn't expect to quickly defeat by magic.
• In Emily the Strange: Stranger and Stranger, Emily does this with the Black Jackal spider. Even so, the bite still partially paralyzes her.
• In the Erebus Sequence, this is given to someone without their knowledge; Rafaela has been secretly building up Lucien's immunity to the poison Golia uses due to the (correct) fear that it will eventually be needed.
• Fate/strange Fake: False Assassin mentions that she trained to be able to imitate Hassan of Serenity's technique Zabaniya: Delusional Poison Body, which turns her into a Poisonous Person. Her training made her immune to many poisons.
• In The Folk of the Air, Jude Duarte has been intentionally ingesting small amounts of the various Fae poisons in order to gain an immunity to their deadly effects over time. This backfires though as she eventually becomes addicted to these poisons.
• In the Gaunt's Ghosts novel Traitor General it is mentioned that the Nihtgane partisans have built up immunity to the poisons in the Untill fauna.
• In Kim Newman's The Hound of the D'Urbervilles, in an international meeting of bad guys, Rupert of Hentzau passes around a flask that no one takes since nobody trusts the others. Even after Rupert openly takes a drink, Colonel Moran thinks to himself that he could have built up an immunity, and mentions that Madame Sara (another Victorian villain) who does take a drink, likely has made herself immune to all poisons.
• In The Hunger Games President Snow tried to build up a resistance to all of the poisons used to kill his opponents, but wasn't always successful, hence the smell of blood from the long-term injuries he's suffering from.
• This is a plot point in Sharyn McCrumb's novel If I'd Killed Him When I Met Him.
• In The Culture novel Inversions, a doctor called Vosill is called to treat a man being tortured, only for him to die suddenly. Suspicious, the Torture Technician insists that Vosill taste the medicine that she just gave the deceased, but it has no effect. Later when the doctor's assistant goes to taste the medicine out of curiosity Vosill quickly stops him, implying this trope. It's strongly implied that Vosill is a Culture agent, so would be immune to poisons and disease thanks to their advanced technology.
• In ''The Journey of The Catechist" Etjole Ehomba can talk to animals, and a snake puts a very slight poison into his waterskin due to his politeness. He then shrugs off a poisoned dart after having built up an immunity. At which point the dart shooter decides to switch to much more effective magic, and kills Etjole outright.
• Journey to Chaos: Tiza states that her apprentice training included small doses of different poisons to develop an immunity. She refuses to say which ones because it is a secret but one of them comes in handy when a trio of zombies try to kidnap her using chloroform.
• The murderer in the Lord Peter Wimsey novel Strong Poison builds up an immunity to arsenic in this way. This does not work in Real Life... though the reference books Lord Peter reads really do exist, and they really did claim that it worked.
• The Last Adventure of Constance Verity: After subsisting on moldy bread and troll blood for a week, the blood gave Constance Verity an immunity to all poisons. Considering all of the enemies she's made, she's put it to good use.
• Malus Darkblade develops dermal immunity to poison after years of smearing himself with venomous slime of the huge fearsome lizard he uses as a mount, which he'd been doing so that the beast would allow him near it.
• In the Paradox novel Even the Wingless after almost being poisoned with hekkret, a recreational drug for the Chatcaava but a deadly poison to most Alliance races, Eldritch ambassador Lisinthir starts smoking small amounts of hekkret to build up an immunity. Unfortunately, he becomes addicted, and it doesn't provide total immunity against the daily attempts to poison him as he starts vomiting blood.
• Phoenix and Ashes: The aftermath of his World War I experiences has Reggie taking lots of sedatives in order to sleep at night (enough that he's getting concerned). Alison isn't aware of this, so when she injects him with opiates to keep him prisoner the dosage isn't nearly enough to do the job.
• Liz Williams' The Poison Master averts this: the Master Ari Ghairen modifies his own body with spider and snake genes to be both resistant and toxic, in an effort to keep up with the cold war in his Guild.
• The Battle of Wits scene in William Goldman's The Princess Bride. The Man In Black has just tricked Vizzini into consuming poisoned wine, and reveals to Buttercup that the wine he'd consumed was also poisoned; he had developed immunity to the poison via this method.
• Rappaccini's Daughter: Rappaccini's lifelong obsession with poison inspired him to nourish his daughter with poison from birth. The result is that Beatrice is poisonous herself and also immune to the vegetable poisons she's been fed on. A short but promising romantic interaction between Beatrice and the student Giovanni prompts Rappaccini to lure Giovanni to his garden repeatedly so that he becomes like Beatrice and can stay with her.
• A plot point in Gary Jennings' Raptor, becoming something of a Chekhov's Gun. The idea is that a person can become poisonous, by taking small amounts of poison, and kissing or sleeping with that person will poison his or her partner.
• Inverted in the Ravnica Cycle. Agrus Kos has used so many teardrops to patch himself up over his long career as a Wojek officer that he has become resistant to their effects. Worse, the toxic buildup of residual mana in his body means that every 'drop he uses brings him one step closer to a potentially fatal heart attack.
• In River of Teeth, Hero has acquired a poison immunity by taking small doses of poison with their iced tea each day, though it's never specified which poison in particular it is.
• Saintess Summons Skeletons: The [Venerable Physique of the Primeval Void] skill is primarily focused on gaining resistances or immunities through prolonged exposure to things, such as enduring fire or force damage to gain explosion resistance, or exploring pitch-black dungeons to gain Innate Night Vision. Sofia makes extensive use of [False Immortality] runes to speed things up, letting her blow herself up, or get killed in the dark by True Shades, over and over.
• In Kalki's classic Tamil novel Sivakamiyin Sabadam (Sivakami's Vow), the villainous monk Naga Nandi builds up an immunity to cobra venom. It gets to the point that it runs through his veins instead of blood, and cobras come flocking to him, attracted by the scent.
• The Dornish in A Song of Ice and Fire are rumoured to put extremely low doses of snake venom in their food along with all the spices, which may be an allusion to this trope. It's supposedly done more for the mild numbing, tingly effect and/or Macho Masochism (a la fugu) than a conscious attempt to build up immunity, though... that is, if it's not just a lie they tell to outsiders.
• Lily of Spy Classroom is naturally immune to virtually all toxins, which is why her spy speciality is making and using them on other people.
• In the Tales of the Five Hundred Kingdoms book The Snow Queen, the Godmother Aleksia is using her Magic Mirror to gather information on a tyrant that she will need to deal with. She notes that the tyrant visits his Alchemist daily for a concoction made of thirty common poisons, which gives him immunity to all but truly exotic poisons (and the reason why he doesn't need to employ a tester). For the truly exotic poisons (which are usually slow acting), the alchemist would have the antidote handy.
• The A. E. Housman poem "Terence, This Is Stupid Stuff"" retells the legend of Mithridates, a king who over the course of his life ate small doses of poison in his food to slowly build immunity to poisons and thus foil potential assassins. This story is used as an allegory; Housman's poem claims that the purpose of his poetry is to inoculate the reader against the evils of the world by describing them in palatable verse.
• Three Dark Crowns: Thanks to her Arron training Katharine has this for a variety of poisons, but it has come at the cost of her health.
• Sam of Villains by Necessity has developed one of these to every poison he's likely to encounter in his career as an assassin — except alcohol. He actually chides his Evil Twin for poisoning a knife with a toxin they are both immune to while they fight.
• So I'm a Spider, So What?:
  • The heroine gets a rather high poison resistance (and Corrosion resistance, too) from being forced to hunt for prey in a dungeon where every creature is poisonous to various degrees. She even ups this by creating globules of Poison that she uses on herself to build it up further: something that many other Magic Users thought was impossible to accomplish.
  • Turns out in this RPG Mechanics 'Verse, you can build resistance to anything this way. Including building resistance to the Earth element by flinging boulders at yourself.
• The Story of Saiunkoku:
  • Ryuuki built up a resistance to various poisons mostly thanks to growing up as The Un-Favorite at the bottom of a pecking order of six princes and their mothers. He once realized that Shuurei had been handed a poisoned drink and drank it himself before she gulped it down, counting on the trope to work; it did and he lived to tell, but it still made him rather sick.
  • Sa Sakujun in the same series built up a similar resistance through bored experimentation, not that it does him a lot of good in the end.
• The entire Agriche family in The Way to Protect the Female Lead's Older Brother practices this due to their rather unorthodox way of raising children. Exaggerated by Roxana, who consumes so much poison (albeit it has less to do with acquiring immunity and more with feeding her butterflies) she eventually becomes a Poisonous Person.

Live-Action TV

• In 1000 Ways to Die, a man decided to pick up a spider and let it bite him to gain immunity to its venom. Naturally, since he had no idea what he was doing, the bite kills him.
• Babylon 5:
  • In "Intersections in Real Time", Sheridan is being held prisoner by Earthgov and subjected to interrogation. At one point, the interrogator is eating a sandwich with delight and offers it to Sheridan, pointing out that he's eating it with no ill effects. And he assures Sheridan they have no desire to kill him until after he's been broken. It's only after Sheridan finishes eating that the interrogator mentions that it contained a powerful toxin that the latter has built an immunity to. The toxin doesn't kill Sheridan but makes him very sick, as intended.
  • When Mollari becomes Emperor but ends up a Drakh thrall, he eventually discovers that the parasite the Drakh implanted in him to keep him under control Can't Hold His Liquor, something Londo himself can, having indulged in wine, women and song regularly for decades. This allows him to act against his controllers if he drinks the Keeper into a stupor first. Unfortunately, over the course of nearly twenty years together, the Keeper gradually develops a tolerance, eventually reaching a point where the amount of privari needed to incapacitate the Keeper is close to the amount needed to incapacitate Londo himself, reducing his ability to act when he's finally free.
• The Cape, a 2010-2011 series, used it when the titular character, learning he was dealing with a poisoner, took it upon himself to work up immunity to everything the guy was likely to utilize. We didn't get to see if the immunities actually HELD, because the guy just tried to run him through.
• In the Community episode "Introduction to Statistics", Jeff invokes this trope as the reason Annie's crying would no longer work on him. It does not work.
• Forever Knight. Dr. Natalie Lambert tries to wean Nick Knight off his vampirism (which she thinks is mostly psychological) by encouraging him to eat small amounts of food, take garlic pills and use a sunbed. He's also shown touching candle flames and exposing himself to religious symbols to deal with his fear of them. In the past just trying to touch a cross caused Nick's hand to burst into flame, whereas now he only gets a minor burn. This proves useful when he's able to ward off his sire LaCroix by holding a cross; even though it should affect Nick just as much, LaCroix breaks and flees before he does.
• In the Halloween episode of Game Shakers, "Scared Tripless, this was part of the prank Double G played on the kids, primarily his son. Since the previous Halloween, he had been taking small amounts of venom so he can fake his death after being bitten by a snake. While it is successful, he forgets that snake bites can become infected and the doctors have to give him a shot in his butt to prevent it.
• H₂O: Just Add Water: The light of the full moon grants mermaids extra power, but also makes them loopy or suffer from a Superpower Meltdown. The more full moons a mermaid experiences, the better control she has over the moon spell; by mid-season two the mermaid trio was able to remember what happened while they were under the effects. By the third season, it was no longer a problem. The cast of Mako Mermaids: An H₂O Adventure were able to figure out that placing a mermaid in the Moon Pool during the full moon was far more beneficial to helping her control the moon spell than trying to avoid it altogether.
• In a sketch in Human Giant a contestant practices for a literal gas guzzling contest (as in drinking gallons of petrol and yes it was shown to be as deadly as that sounds) by drinking various poisons including paint thinner to build up an immunity. he wins but doesn't have a car.
• An inadvertent version in I, Claudius. The wife of a Roman official is drugging his wine so she can have an affair with Sejanus while he's asleep. Sejanus convinces her they have to Murder the Hypotenuse instead, as he'll eventually become resistant to the drug.
• In Iron Fist, Colleen claims that Bakuto made her swallow tarantulas whole in order to develop an immunity to their venom, but Danny doesn't buy it and she admits she made it up.
• Law & Order: Special Victims Unit episode "Wet". A man is believed to have committed murder by poisonous mushroom spores. He built up an immunity to them through years of exposure.
• On My Name Is Earl, Catalina has been given some tea spiked with sleeping pills by a vengeful "Crazy Witch Lady" (played by Betty White). She winds up in the woman's basement with Earl and company...but she ends up tying herself up, saying that because her drinks have been spiked with so many date-rape drugs over the years, she's developed a tolerance, but couldn't make a woman who reminded her of her aunt back home feel bad.
• In one episode of NCIS, the victim turns out to have been a hitman and his murderer is one of his intended victims. He used snake venom, and the woman kept snakes and developed immunity, although she didn't specify whether this was her intention or just a side-effect of her preferred pets.
• In the Psych episode "This Episode Sucks", Lassiter is put to sleep with chloroform and then wakes up saying he's been building up an immunity to chloroform over the years.
• Christopher Walken's Saturday Night Live smooth-talking ladies' man character "The Continental" has been maced so many times he's built up an immunity to it. This, however, doesn't keep him from getting punched in the face.
• Stargate-verse:
  • In Stargate SG-1, a single shot from a Zat'nik'tel will typically cause extreme pain and/or unconsciousness in subjects. However, it seems that years of exposure to hits from this kind of weapon is enough to build up a tolerance. In later seasons, we routinely see team-members who've been shot with a Zat suffer only mild discomfort and quickly shrug it off, while those who've never been Zatted before get consistently knocked out. This ends up being a plot point in an episode, where O'Neill has to run to the stargate in order to activate it and force the local Energy Beings away, allowing the rest of the team to flee. He uses zat shots to temporarily make his ionized body repel the creatures, but the effect wears off after a minute or so. He can't zat himself again, as a second zat shot within a certain time frame is fatal. Luckily, Teal'c shows up just in time and zats the ground next to O'Neill to the same effect. Wonder why no one thought of that one before.
  • Wraith stunners from Stargate Atlantis seem to have the same effect as well: a glancing hit to a limb sometimes fails to knock out characters like Ronon who have been shot many times before.
• Star Trek: Deep Space Nine: In the episode "Ties of Blood and Water" the Vorta Weyoun reveals that Vorta are immune to most known forms of poision, which he demonstrates by drinking from a bottle of kanar that had been spiked with enough poision to kill a dozen Cardassaians. Weyoun comments that it's a useful ability for a diplomat.
• The Twilight Zone (1959): In "The Jeopardy Room", the Soviet commissar Vassiloff tricks the defector Major Ivan Kuchenko into drinking wine mixed with a sleep drug by drinking first. He built up an immunity to the drug by repeatedly taking increasing doses over time.
• In The Vampire Diaries Katherine has built up an immunity to vervain, she can still get disabled by it if taken by surprise by a large enough dose but she gets over it much faster. Stefan uses this technique to get over his addiction to human blood.
• One clip on World's Dumbest... features mystics from India who spend their lives building up a tolerance for cobra venom. They then hold a competition to see who can take the most bites before conking out.

Radio

• Horribly subverted in the Sherlock Holmes (BBC Radio) episode "The Saviour of Cripplegate Square". The murderer regularly doses the victims with arsenic until they build up a tolerance ... so that they can subsequently be subjected to arsenic withdrawal and die without a trace of it in their systems.

Tabletop Games

• Dungeons & Dragons
  • 1st Edition Advanced D&D supplement The Rogues Gallery. The NPC Lassiviren the Dark has taken steadily increasing doses of poison over the years. As a result, few poisons affect him.
  • Forgotten Realms
    • Supplement Drow of the Underdark. During their training, drow have successively larger doses of drow sleep poison and various spider venoms administered to them. This gives them poison resistance ranging from +4 vs. random ingested poisons to +7 vs. spiders' and their own sleep poison.
    • Menzoberranzan boxed set. Over his life, the drow Mage Lord Jalynfein (AKA the Spider Mage) has eaten spider venoms of increasing strength. This has caused him to develop an immunity to the poisons of most known spiders.
    • 2nd Edition supplement The Code of the Harpers. The Dark Dagger is a group of drow thieves who often use poison. They are mostly immune to their own poison because they have taken gradually increasing amounts of it over their lifetimes.
  • Dark Sun boxed set DSE1 Dragon's Crown, book "The Road of Fire". The poisoner Wheelock is immune to all poisons found on Athas because of years of exposure to them.
  • Polyhedron magazine
    • Issue #64 adventure "Short People". Two halfling thieves try to trick the Player Characters into drinking wine and ale laced with paralysis poison. They will drink along with the PCs because they have built up an immunity to the poison over the years and are not affected by it.
    • Issue #94 article "Elminster's Everwinking Eye". Fanaeth Torslar is a master thief who has exposed himself to so many poisons over the years that he is not affected by most common poisons.
    • Issue #98 adventure "A Handful of Dust". The thief Pence has created a system of immunizing people against specific ingested poisons by feeding them gradually increasing amounts of the poison at regular intervals.
  • Dungeon magazine, issue #53 adventure "Spellbook Masquerade". Kelsey Kincaid has spent years building up her immunity to many poisons. As a result, she receives a +4 to all saving throws vs. poison.
  • 3rd Edition:
    • Members of the Assassin Prestige Class received increasing saving throw bonuses to poison as they went up in level due to their use of and exposure to poisons.
    • Supplement Creature Collection. The Ubantu tribesmen coat their weapons with poison. They've developed a racial immunity to it due to generations of exposure.
    • The 5th edition version of the Eberron setting gives us the Artificier (Alchemist subclass) that can become resistant to both 'Acid' and posion.
• Hollow Earth Expedition, supplement Mysteries of the Hollow Earth. Cannibal tribes are known for their skill in creating poisons. Some of them include small doses of poison in their meals to build up an immunity to them.
• In Mice and Mystics, the first mouse to be captured with at least one poison wound will not receive poison wounds until the end of the chapter.
• Pathfinder: The Alchemist class slowly gains resistance to poison over the first nine levels of their career before finally becoming completely immune at level ten, presumably using this method.
• Spirit of the Century features an endurance stunt called Developed Immunities that makes a character flat-out immune to "common" poisons and gives +2 or +6 to rolls to resist uncommon ones, depending on whether or not the character has encountered them before. A character who combines this stunt with a sufficiently high Endurance trait has nothing to fear from any save perhaps the most outlandish poisons. (As they run on their own versions of the same system, the exact same stunt can also be found in Starblazer Adventures and Legends Of Anglerre. The also related but somewhat less pulp-ish The Dresden Files omits it.)
• Traveller: SORAG: Handbook of Organization and Equipment gives the option during PC creation for a SORAG agent to be assigned to the Medical Division. During the assignment, the agent can be given immunity to Truth Drug by injections of small doses of the drug over an extended period under carefully controlled conditions to build up the body's natural resistance. There is a small chance of the agent's body resisting the treatment, in which case no immunity is gained and the agent's Endurance drops by 1 point.
• Warhammer: Ogre butchers (wizards that eat all kinds of dangerous things to cast spells) have the immune to poison rule, so one would assume they have built up a very handy poison immunity.
• Warhammer 40,000: Orks of the Snakebites clan keep a variety of extremely venomous snakes as pets that they allow to bite them throughout their lives, sucking out most of the venom after each bite but allowing some to remain. Over time, this allows them to develop a considerable resistance to poison.

Video Games

• The Roguelike game ADOM gives poison resistance to players who eat corpses of giant spiders.
• Baldur's Gate III: Minthara takes small doses of various toxins with her meals to build up an immunity, which can result in an accidental Drugged Lipstick if the player is romancing her.
• In Batman: Arkham Knight, Scarecrow has acquired partial immunity to his own fear toxin. However, a large enough dose can overpower it, and like in the Blackest Night example, he still does fear Batman.
• Because of all the experimenting she did on herself, Beatrix from Battleborn has acquired an immunity to her own toxins. That along with half of her body being mechanical.
• Blaster Master Zero 3: Jason starts misuing his Accel Charger in order to traverse Super-dimensional Space, and comments over time that he's getting more and more comfortable with it, wondering out loud if he's just getting acclimated to the hostile nature of the place. Eventually he's able to enter Super-Dimension Space without VRV and survive without life support... and an extended stay completes his transformation into a Super-Dimensional Being who can't safely exist in normal space. The same happened to Eve, so he's fine with it.
• In Dragon Age: Origins, Oghren has spent so many years mistreating alcohol, that he no longer suffers any negative effects from whatever he drinks. Taken further in Awakening where during the Joining ceremony, upon drinking the concoction (which contains darkspawn blood among other unpleasant ingredients), which typically renders the new Wardens unconscious, he merely burps and claims it was "not bad".
  • In addition Awakening introduces the Vitality skill tree, which provides health bonuses. One of the descriptions mentions the character consuming small amounts of toxic materials to build up resistance.
• In the final route of Duel Savior Destiny following the end of Mudou and Kaede's Duel Boss Fight the latter collapses after winning the fight due to poison. She returns in the endgame citing this for why it wasn't an outright double kill.
• The Elder Scrolls
  • Throughout the series, this is a racial trait of the Argonians. Living in the Black Marsh with so many poisonous and toxic lifeforms has made the Argonians almost totally immune to natural and magical poisons. Likewise, the Bosmer (Wood Elves) and Redguards typically have lesser (around 50%) natural racial resistances to poisons.
  • In background lore, the Khajiit are far less susceptible to the Fantastic Drug, Moon Sugar. Moon Sugar is sacred in their culture, and they believe it to be "crystallized moonlight." Nearly all of their food uses it in some form or another, hardening their bodies to it. Still, overeating the sweetest of Khajiit foods can overwhelm even their resistance.
  • In Skyrim, an alchemy perk 'snakeblood' gives you 50% resistance to poison, which follows perks that involve creating poisons and eating ingredients — implying you've had so much passive exposure to the various poisons that they don't work on you anymore.
• Elona: The description for the Poison Tolerance feat explains it as being due to exposure:
  Being a taster for a noble grants you resistance to poison.
• Etrian Odyssey has a mechanic where inflicting a status ailment or bind on an enemy or ally will increase that character's resistance to that effect for the remainder of the battle. In Legends of the Titan, Arcanists have a skill called "Release Spell" that undoes this.
• Fallout: New Vegas:
  • Having your limbs crippled 50 times gives you increased resistance to future broken limbs with the notification that "Repeatedly breaking bones has led them to become stronger (somehow)." This is actually truth in television - because adult bones usually lose calcium slowly after time, they tend to become stronger after the process is reversed during the knitting of bones.
  • In the Dead Money DLC, Dean Domino is resistant to the poisonous cloud of the Sierra Madre due to having been a resident of the place for 200 years. Having him as a companion will grant you a temporary immunity towards the cloud.
• In Final Fantasy Crystal Chronicles, you meet the Selkie De Nam, who decides that the best way to deal with the deadly Miasma is to try to build up a resistance to it by drinking water with miasma mixed in. It doesn't end well.
• In Green Hell, it's mentioned early on that the natives are immune to the local poisonous frogs because of this. Becomes a Chekhov's Gun later when the frog poison turns out to be the missing ingredient of the miracle cure that Jake has been hunting the whole game.
• Grounded: The mutation "Mithridatism" grants resistance to poison, and is acquired by killing wolf spiders; the more, the better. The description suggests that it's a result of all the poisonous bites you've received, although don't actually have to get bitten for it to work. (Good luck with that, though.)
• In Injustice 2, Harley Quinn mentions using Scarecrow's gas as a recreational drug, which comes in handy in a fight against him.
• After extensive exposure to the powers of darkness, it's revealed in Kingdom Hearts 3D [Dream Drop Distance] that Riku has become immune to the corruptive nature of darkness, meaning Xehanort is unable to use him as a vessel any longer.
• Knight Bewitched 2: Malady has the Innoculated passive, which grants her immunity to poison. She gained this ability due to constantly working with poisons and chemicals.
• The Legend of Zelda: Breath of the Wild: The Zora are portrayed as being especially vulnerable to electricity, which is inconvenient because Shock Arrows are needed to incapacitate the Divine Beast Vah Ruta that has been causing havoc for the Lanayru Province. King Dorephan and Prince Sidon decide to seek help from Hylians, who lack said vulnerability, but one Zora named Seggin instead tries to develop an immunity to electricity by repeatedly touching a Shock Arrow. He is apparently making some progress, as it's mentioned that he can hold it far longer than any other Zora, but it's still excruciatingly painful.
• In Lost Souls (MUD), once you have any degree of poison resistance, exposure to poison will develop it further.
• In Mass Effect 2, failure to realize that without constant supervision, a sedated Shepard won't stay that way for long, ends up foiling the Indoctrinated Alliance agents in The Arrival. One medical report in The Arrival even mentions their frustration that it was necessary to increase every round of sedatives administered because Shepard's system simply grew immune to the previous dose, given only four hours earlier. It's justified by their cybernetics, which also allows them to survive otherwise fatal poisons (and ryncol).
• In Mega Man Battle Network, deliberately ignoring the rules of the Navi Customizer results in MegaMan getting random bugs that impede his abilities in battle. However, in the third game, persisting through enough battles with these bugs will unlock the BugStyle Change, which comes with BugStop, allowing MegaMan to use the Customizer without worrying over bugs.
• In the Monster Hunter series, the titular monsters get an increase in poison resistance each time the poison status effect is applied. The same is true for KO, paralysis, and traps.
• NetHack (what else?) features varieties of poisonous meats that have a slight chance of providing permanent poison resistance when consumed. You can similarly gain resistance to heat, cold and electricity by eating certain corpses. You can even get immunity to Disintegrator Rays that way.
• Neverwinter Nights:
  • Acquired poison resistance is one of the perks of the assassin class.
  • One quest has a werewolf character who claims to have overcome his weakness to wolfsbane herb by posing as a merchant and selling it to werewolf hunters, while secretly exposing himself to small quantities of it.
• Octopath Traveler II: Castti, according to banter she has with Osvald, is immune to most poisons as a result of creating herbal medicines and testing them on herself. While this doesn't mean she's immune to poison from enemies, it does mean she's able to survive in Trousseau's poisonous rain much longer than anyone else.
• Persona 3: It's extremely strenuous traversing inside Tartarus, the reasoning is explained by Akihiko and Mitsuru after the Protagonist, Yukari and Junpei experience its effects. Gameplay wise in the beginning it won't take many fights to put the Protagonist, Yukari and Junpei into "tired" status. As the group levels up more and more their resistance to the exhaustive effects of Tartarus strengthens but does not disappear entirely.
• Subverted in Ragnarok (Roguelike). While it's possible to acquire poison immunity in a similar manner (though most venomous animals are still poisonous to eat), the poison of the phantom asp is so potent it has a chance to kill even through supposed "immunity."
• In Rune Factory 3, your protagonist has a "Poison" skill that goes up whenever he is poisoned by the enemy, or whenever he successfully poisons one of them with an attack. One of the benefits of raising it is it makes you harder to be poisoned.
• Suikoden II:
  • One country has a sighting ceremony where the knight and the ruler mix drops of their blood in a bowl and sip from it. One character builds up a tolerance until he can make his blood lethal to others.
  • The only reason that Riou can eat his sister's "food" is that he's developed an immunity to it.
• One of Touhou Project's protagonists, Cute Witch Marisa Kirisame, is revealed in supplementary materials to have exposed herself to so many poisons and toxic substances over the course of her magical research that she's developed a resistance to mercury poisoning.
• One World of Warcraft Horde quest has the player fight venomhide ravasaurs (venomous raptors) and gets splashed with their toxic blood in order to become immune. This is the first step to getting a venomhide ravasaur mount.
  • Worgen have a racial ability, Aberration, which reduces the duration of curses and diseases they are afflicted with. Presumably, because they're already afflicted with the Worgen curse.
  • Traveling through Gorgrond, players can stumble across a pool of water filled with snakes and the corpse of an Orc floating in the middle. Looting the body reveals that the Orc was attempting to invoke the trope to make him immune to snake venom; only for the snakes to wind up killing him.

Web Comics

• The Adventures of Dr. McNinja: Dan McNinja doesn't need to develop an immunity to poisons. His body separates it out and stores it up so he can squirt it out of his eyes. "Like a toad."
• Dead Winter: Black Monday Blues' mother evokes "building a tolerance" right before a pair of bad guys collapse.
• Ensign Sue Must Die: Mary Sue built up an immunity to phaser blasts this way.
• Invoked and then immediately subverted in this Exiern page:
  King Urtica: I trust I have a resistance to the poison in this wine. (sips)
  Madam Amalia: Any poison I would use wouldn't give you the opportunity.
• Girl Genius:
  • Gilgamesh Wulfenbach has immunity to many many things. Because his father "figures that a ruler should be... hard to kill", what with the people across all of Europe who're upset at killing that Mad Scientist or the process of bombing this town... which extends to his heir. This came in useful in the arc where Tarvek suffered a particularly nasty and rare disease — Gil was able to disregard the risk of infection.
  • Those with Smoke Knight training are also immune to ordinary soporifics, as seen with Violetta and Martelus during the tea break at the Corbettites. Unfortunately for Martelus, those training sessions didn't include immunity to a sap to the head.
• In How to be a Werewolf getting scratched by a werewolf provides immunity to their bite. Vincent was clawed up by his sister Malaya when he was a toddler, with the result that he doesn't turn after one of Connie's pack bites him.
• Keychain of Creation:
  • Besides disturbing quantities of alcohol, Ten Winds has reportedly been exposed to toxins, drugs and pharmaceuticals of all kinds and quantities from across Creation over his multi-century lifespan. Stack that on top of his already supernatural Exalted metabolism and you have someone who is very hard to poison, as illustrated here:
    Ten Winds: [Sipping drink] Why, this is quite a classy sedative.
    Nova's maid: It's imported.
  • Invoked on Marena by her mother in her childhood, as it turns out — one of Marena's many resentments towards her.
• Latchkey Kingdom has princess Rosaline Lannistark, though her parents were a bit mean-spirited in teaching her.
• One (SFW) Oglaf comic shows an unexpected downside of this trope. In it, a very experienced food taster boasting that he's immune to pretty much everything by now to his latest client. Said client then keels over after one bite of the poisoned meal that the taster was completely unaffected by.
  Food Taster: You won't be wanting that, then?
• Riverside Extras: Subverted. Ophelia does drug both drinks, foiling Simon's attempted Poisoned Chalice Switcheroo, making a dramatic exit as Simon lies on the floor twitching...only to stumble and see double once she's left the room. She just had the advantage of anticipating the effects of the ether. Fortunately, the ether's effects are nonfatal for both of them.
• In Something*Positive, Kharisma tries to kill Avagadro with cyanide, which he has built up an immunity to after being poisoned by so many people over so many years. He says that he has grown accustomed to the taste, and now puts it on his cereal.
• Spacetrawler: Dmitri believes that a person can become immune to stun guns, and has started shooting himself repeatedly in order to acquire it. Results: he acquires a taste for stun-gun shots. And immunity. In that order.
• Your Throne: Lady Medea Solon knows a lot about poisons and has aquired immunity to most. Unfortunately, it is her own father who tries to poison her, and he knows the few combinations of poison she isn't immune against.
• Isaac of Val and Isaac has managed to achieve this by accident due to him drinking poison that his colleague Minow keeps putting next to his coffee.
  Pirate: That doesn't explain-
  Isaac: It happens twice a week.

Web Original

• In Dino Attack RPG, Amanda Claw built up immunities to several different poisons and toxins by taking small doses during her years as Silencia Venomosa. This protected her from the poisonous gas in the Mindstorms, Inc. office building. She also hoped this would protect her from the XERRD toxins, but evidently that is one immunity she never acquired; still, she held out longer than most of her fellow Dino Attack agents.
• DSBT InsaniT: Michael and Ashley are immune to their own poisons...but not each other's. This is key in defeating them.
• In Fen Quest, it's mentioned that immunity to Tomato's deadly venom must be periodically "maintained" by ingesting some of it, otherwise, it wears off over time. When his sister Cheese is accidentally stung after months apart, they determine she still has enough resistance to survive unaided, but will nonetheless get gravely ill without an antidote.
• A milder example, as it's not really a poison. In The Nostalgia Critic's music video "F**king Love Christmas", Critic sings a psychotic metal song about how much he loves the holiday. He terrifies Malcolm and Tamara so much that Malcolm has to tranquilize him. He then sings that he built up an immunity to tranquilizers because of his insane love of Christmas.
• In The Orphan and the Jeweler (a companion story to Diablo III), Stepfather Yao administers tea poisoned by a lethal plant known as scorpion root to Covetous Shen. After drinking the tea and remaining unharmed, Shen remarks that his immunity comes from a time when he was trapped on an island full of scorpion root and poisonous snakes and was forced to eat them to survive, thus granting him immunity to most poisons. As one might expect, Yao is properly baffled by this.
• In the SuperMarioLogan episode "Shrek's Diet", it is revealed that the diabetes Shrek got from eating nothing but cheesecake his entire life has caused his body to build up an immunity to diabetes.
• Sylvester, in Twig, is the recipient of the Wyvern formula, which consists of a variety of natural toxins and poisons which is regularly injected into his brain in order to improve brain plasticity and healing, which grants him the ability to rapidly retrain himself in different skillsets. As a side effect, he's developed resistance to a variety of common poisons, though there's still more that can beat him.
• Parodied in this CalebCity skit where the bad guy who liberally uses You Have Failed Me for the slightest inconvenience tries to choke out his last surviving minion for backtalking him over it, only for the minion to tell him he's been choked out so many times he no longer needs oxygen.
• Played for laughs in Camp Camp, where deranged cult leader Daniel accidentally poisons himself with his own punch. When he comes back in a later episode, he reveals that he's done this so many times he's built up an immunity. Of course, it was still bad enough to hospitalize him, so he might be lying about that.

Western Animation

• Arcane: Silco is completely immune to the toxic mine air he uses to punish his disgruntled chembaron allies, only wearing a mask briefly to taunt Finn. It suggests he has suffered far more in the aforementioned slave mines than those present in the meeting.
• The eponymous Archer has been poisoned and drugged so many times in his line of work, he can metabolize and shake off toxins with ludicrous speed.
• Dan from Dan Vs. has been hit with tear gas and pepper spray so many times that he doesn't feel their effects anymore. He can even tell the differences.
• Similar to the SNL example above, in Family Guy, Quagmire has also built up an immunity to mace after being pepper-sprayed so many times.
• In Frisky Dingo, Killface tries to poison Phil with a "vitoxin" poison but finds out Phil built up an immunity to it, coincidentally using small doses to help him lose weight. Unfortunately for Phil, he didn't build up an immunity to be accidentally shot in the head by a sniper aiming for someone else.
• Snake Eyes in G.I. Joe: Renegades takes multiple hits from poison darts thanks to a built up immunity. They're still enough to weaken him though.
• Similarily, but on a more technological level, Old Man McGucket from Gravity Falls has a built-up immunity to the effects of the Mind-Wiper Gun due to using it on himself so much. Played With in that the Mind-Wiper Gun doesn't have any effect on him because it has already done all the damage it possibly could.
• Dale Gribble in King of the Hill was unaffected by police tear gas stating that he kills squirrels with stronger gases. Given that he's an exterminator spraying poisonous gases without wearing a mask and while his health slowly deteriorates (alongside with smoking).
• The Life and Times of Juniper Lee: Toward the end of the series, June lets her brother Dennis in on The Masquerade partially because they've used memory erasing powder on him so much that he developed an immunity to it.
• In Metalocalypse, Pickles is immune to the mind-erasing effects of Totally Awesome Sweet Alabama Liquid Snake, and every other drug as well, as the result of doing "government weed" daily since the age of 6.
• In the "Cartoon Smokers" sketch from the Robot Chicken episode, "Triple Hot Dog Sandwich on Wheat", Olive Oyl is among the famous cartoon characters being treated for lung cancer in a hospital, due to years of exposure to secondhand smoke from Popeye. Ironically, Popeye is just fine due to immunity to lung cancer developed by the antioxidants in his spinach.
• Rocky and Bullwinkle: In one segment of Peabody's Improbable Histories, Mr. Peabody uses this trope to help the husband of Lucrezia Borgia.
• Downplayed variant in Sally Bollywood. When everyone in school gets sick except for Sally, it turns out it was because the lunch that day used an extra strong pepper. Sally was the only one unaffected thanks to her heritage meaning that she was used to eating food that spicy, having eaten that same pepper her entire life.
• Nigel Thornberry claims in The Wild Thornberrys that he's developed an immunity to poisonous plants by rubbing their juices all over his body.
• In Young Justice (2010), Aqualad reveals that he is "largely immune" to the jellyfish toxin that Cheshire uses to coat her darts. Largely doesn't mean completely, though: he was weakened by it, more with each dose. Of course, this may be a result of his Atlantean biology and not an acquired trait.

Real Life

• As noted above, the official term for this (Mithridatism) comes from King Mithridates VI, a king of Pontus. He feared assassination so badly that he took small doses of poison regularly in order to become immune to the poison's effects. This backfired when the king was eventually conquered. He attempted to commit suicide by poisoning himself only to find that he was immune; depending on the version of the story you hear, he then either fell upon his sword or had an underling run him through. In either case, the poem says it best: "Mithridates, he died old."
• Supposedly this was a very common practice amongst the upper classes in Ancient Rome. At any rate, it is referenced in the Cambridge Latin textbook series with a similar outcome to Mithridates.
• Human body quickly builds up a tolerance to most alkaloids (ranging from the relatively harmless caffeine to opiates, nicotine, atropine or cocaine), which drives people slowly to higher doses and addiction. Nicotine from tobacco, in pure form, can kill a fully grown human in amounts as small as 30 mg, which is 1/16th of a peppercorn, and during the 19th century had been used for assassinations, until forensic physicians discovered a way to detect it.
• Bill Haast was one of these until his death at the age of 100. He became immune to most snake venom by injecting himself with diluted venom over a period of time, which was a good thing, because he had garnered 172 bites in his lifetime, and had even survived a blue krait bite - without antivenom, which was something that he didn't think was possible. His blood has been used to help more than 20 snake-bite victims.
  Haast: "It was risky, but I was cautious. When I started in 1948, a doctor said he wouldn't give me a nickel for me living two years. Well, I'm still here, but the doctor died of a coronary."
• According to Deadliest Warrior, the African warlord Shaka Zulu spat poison into his opponent's eyes during battle. He avoided its effects himself by this method, eating small pieces of the plant it came from for years. This may or may not be true.
• While you can't build up an immunity to arsenic, you can build up a tolerance. When American soldiers came to the UK in World War II those stationed in Cornwall often came down with arsenic poisoning from the water that the locals could drink with no problems.
  • One episode of Forensic Files featured a woman who survived doses of arsenic that would have killed a person several times over, mainly because her husband who had been poisoning her gave her small amounts at first and unknowingly made her more tolerant of it.
  • Both these cases are likely actually due to a genetic mutation that results in higher resistance to arsenic.
• This trope ended up backfiring when a man from Russia attempted to swallow small quantities of toxic mushrooms, arsenic, and cyanide daily to strengthen his body and protect himself from death. He later went into convulsions, slipped into a coma, and died without regaining consciousness. As seen here.
• African Honey Badgers. Over their lifetime, they develop some immunity from the poisonous snakes, scorpions, and bees they regularly prey on. In fact, a male bitten on the cheek by a highly toxic puff adder showed signs of severe pain but recovered fully within five hours. Watch it here.
• According to some theories, the Aztecs got their red skin tone from the arsenic in their systems obtained by taking it over time to build up immunity.
• A famous urban myth is Grigori Rasputin - he supposedly had been taking minute doses of cyanide over a long period, and when his meal was poisoned, he ate it and walked away. Given that it should be impossible to build a resistance to cyanide, it's likely that it's not true. More likely is that the poison had either been broken down during cooking by mistake, counteracted by something else he ate during that meal, or even that he didn't eat it at all due to his bad stomach. In any case, later records revealed that Rasputin died of being shot, not poisoned.
• In her autobiography, Venezuelan musician and metaphysician Conny Méndez claimed that, when she was young, one of her uncles decided to make the family immune to cyanide, and convinced them of sprinkling tiny quantities of the substance on their food then increasing the doses little by little. The thing allegedly ended some years later when an apothecary, alarmed with the huge quantities of cyanide bought by the family, sicced the police on them; by then the kids of the family were ingesting without ill effects enough cyanide to kill a normal adult.
• The Rough-Skinned Newt has enough tetrodotoxin to kill a room full of adult humans, as a result of a ridiculous evolutionary arms race with garter snakes. The evidence suggests that each newt eaten adds more to the snake's overall resistance.
• Allergy immunotherapy is a process that gradually reduces immune responses through exposure to minute doses of the allergen. After a few months, the patient only needs a booster shot a couple times a year to maintain it.
• Poison Ivy and certain breeds of Stinging Nettles can have their worse effect counteracted by eating parts of the plant, "Stinging Nettle Tea" is even a known home remedy in some southern US states. Though it's worth noting that most people don't have the famous reaction to poison ivy, so the idea of eating the plant to reduce its effect is moot, while the people who do have that reaction to it... probably shouldn't be letting something that causes swelling anywhere near their throat.
• In feral animal control scientists are working to refine poisons from native plants, the idea being that introduced species will have less tolerance than native species who have been exposed to the same poison for thousands of years.
• Tiger butterflies lay their eggs on toxic plants. When the caterpillar hatches, it first nibbles the plant little by little to build up immunity. Once it becomes immune, then it gorges on the plant.
• This is how vaccines work (though notably not the mRNA ones against COVID-19). Patients are given small doses of often inactivated pathogens, and the immune system learns to fight them. Toxoid vaccines use an inactivated toxin in a literal version of this trope.
  • mRNA vaccines go one step further by inducing your body to make small amounts of the poison (in the form of inactive protein components that duplicate parts of the pathogen) that you are being immunized against.
    • Traditional vaccines could not be made against viruses like Ebola, since there is no "small dose" biologically possible: 5 viral particles are enough to ignite the hemorrhagic fever and the horrible death that comes after. It took very complex recombination of DNA to make a vaccine just to imitate the surface proteins of the Ebola virus.

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