A PharmD reveals the 5 most common OTC medication mistakes — and exactly what to do instead. Simple fixes that could protect your health. After more than 20 years in pharmacy practice, I have seen the same mistakes show up again and again. Not because people are careless — but because nobody told them. Consider this your briefing. Mistake #1: Taking two products with the same active ingredient. This is the one that concerns me most. Acetaminophen (the active ingredient in