Ibuprofen is a non-steroidal anti-inflammatory medication commonly used as a pain reliever and to reduce fever. It is available in many over-the-counter formulations (Advil, Motrin, Midol) as well as in prescription strength medications. Though relatively safe for people, ibuprofen can be toxic for dogs and has a relatively narrow margin of safety, meaning that it is safe for dogs only within a very narrow dosage range.
Ibuprofen inhibits COX enzymes which normally have a protective effect on the mucosal barrier of the gastrointestinal tract, keep blood flowing normally to the kidneys, and help regulate platelet function. When COX enzymes are inhibited, the mucosal lining of the gastrointestinal tract becomes damaged, causing symptoms such as vomiting, nausea, diarrhea, intestinal upset and causing gastric ulcers to form. Reduced blood flow to the kidneys results in kidney damage. Reduced platelet aggregation leads to an increased tendency to bleed abnormally.