Probably any OTC med can kill if overdosed. The tylenol lethal dose is about 10 grams (20 extra-strength tablets) and it causes centrilobular necrosis of the liver.

Do you remember the recent story of the cross-country runner in high school that died of salicylate poisoning from rubbing sports cream on her body? She probably had also taken salicylates from other sources (aspirin) and didn't realize the additive effect.