What should a patient taking Coumadin (warfarin) avoid in over-the-counter medications?

A patient taking Coumadin (warfarin) should be particularly cautious with over-the-counter medications that can increase the risk of bleeding due to anticoagulation effects. Aspirin, as a nonsteroidal anti-inflammatory drug (NSAID), has antiplatelet properties, which can exacerbate the effects of warfarin and lead to an increased risk of gastrointestinal bleeding and other forms of hemorrhage. This interaction is significant because both warfarin and aspirin affect the blood's ability to clot, putting the patient at a higher risk for adverse effects.

While ibuprofen also poses risks, particularly concerning stomach irritation and bleeding, aspirin is more commonly associated with direct interactions that potentiate the effects of warfarin. Acetaminophen is generally considered safer in terms of bleeding risk when used occasionally and in recommended doses, and diphenhydramine typically does not have significant interactions with warfarin. Therefore, among the listed options, avoiding aspirin is crucial for patients on warfarin to maintain safe anticoagulation levels.