There is one drug whose reportedly serious complications are not publicized nearly enough, in my opinion: the blood-thinner Coumadin (warfarin). If you're taking it, your doctor should be continually monitoring its effect via regular blood tests (at least once a month). And even if you've been taking the same dose for years, the degree to which it thins your blood may suddenly change because of changes in your other meds, your diet or your underlying metabolism. That can lead to severe joint problems, gastrointestinal bleeding, strokes and hemorrhage.