Each day, 36 million people pop a pill to relieve the pain of headache, arthritis or muscle ache. A study in the November Journal of Rheumatology found that 25% of them take too much, and risk trading pain relief for serious stomach problems.

The medications are a class of drugs called non-steroidal anti-inflammatory drugs, or NSAIDS, which include aspirin, ibuprofen (Advil, Motrin) and naproxen (Aleve). Many common cold remedies and prescription pain relievers also contain NSAIDs.

All those plastic bottles in medicine cabinets contain warnings and recommended doses, but the study, which surveyed 807 adults, found they're often ignored. Fifty-four percent of the survey participants said they were unaware of gastrointestinal side effects, including ulcers and hemorrhage, and 18% said they had experienced a side effect. Overdosing can happen not only by taking more than the recommended dose but also by taking the next dose sooner than directed, taking more than the recommended number of doses in a day, or unknowingly taking several drugs that all contain NSAIDs.