Several members have raised questions in the last several weeks around the question of whether antacids like garden variety Rolaids or Tums, a class of drugs called histamine H2 blockers like zantac and tagamet, and also proton pump inhibitors (PPIs) like prilosec (the "magic purple pill"), protonix, nexium, etc. that effectively shut down stomach acid may actually be problematic if taken in combination with Iressa or Tarceva (I'm going to focus primarily on Tarceva here, since that's the drug marketed in the US right now).