Ibuprofen, a nonsteroidal anti-inflammatory drug (NSAID) approved by the U.S. Food and Drug Administration (FDA) in 1974 that's used to treat pain and fever, is typically safe. But it thins the blood, which can cause bleeding if you’re taking blood thinners or anticoagulants such as warfarin (Coumadin). It can also cause stomach upset, so take it with meals. Fatalities are rare; but, in 2007, doctors reported two deaths from massive doses of ibuprofen in the Journal of Medical Toxicology. The victims suffered from cardiovascular collapse, increased acidity of their blood, and hypothermia (severely low body temperatures).