Painkiller Risk

Combining painkillers can be dangerous. Patients regularly taking an over-the-counter nonsteroidal anti-inflammatory drug (NSAID), such as ibuprofen (Advil), and aspirin in the same day had two to three times the risk for ulcers and gastrointestinal (GI) bleeding as those who took either alone.

Theory: Acidity in the GI tract reaches more harmful levels when the painkillers are combined.
If you must take multiple painkillers: Ask your physician about adding a proton pump inhibitor (PPI), such as lansoprazole (Prevacid), to reduce stomach acid.