Aspirin is very helpful in preventing heart attacks because it interferes with a normal blood clotting element called platelets. It actually prevents the platelets from aggregating or sticking together to form a clot. Aspirin does this by directly attaching to a portion of an enzyme in the platelets, thereby preventing the aggregation process.
Recently, ibuprofen has been shown to interfere with aspirin's blocking of the platelet enzyme; it essentially "gets in the way" of the aspirin. If aspirin is taken with ibuprofen, it could significantly diminish the effect of aspirin in preventing heart attacks.
I recommend that patients who are taking aspirin to prevent heart attacks and need ibuprofen, take their aspirin two hours before taking ibuprofen, such as first thing in the morning with breakfast. In this way, the aspirin is able to interfere with the platelet aggregation by binding to the platelet enzyme before ibuprofen is around. I also recommend that both aspirin and ibuprofen be taken with food.
Medically reviewed by Robert J. Bryg, MD; Board Certified Internal Medicine with subspecialty in Cardiovascular Disease
"Aspirin: Mechanism of action, major toxicities, and use in rheumatic diseases"
"Nonselective NSAIDs: Overview of adverse effects"