WMG / Sherlock S1 E1 "A Study in Pink"

• Both pills were poison. Jeff Hope had already taken an antidote, or developed an immunity.
  • Assuming he ever actually takes the pill (which we have only his word to go on), actual immunity wouldn't be needed. It could just be an overdose of medication he's been on for a couple years, and has built up a tolerance to.
  • Or, only one pill was and he would take the other one, since he was dying anyways. And was just lucky, so far.