Over-the-counter Creams and Ointments
You don’t often think of over-the-counter (OTC) creams and ointments as products that can interact with prescription drugs. But they can cause drug interactions the same way that oral medications can.
Most patients are aware that warfarin interacts with many prescription drugs as easily as OTC medications. Many people believe that medications taken by mouth are more readily available through the bloodstream to provide relief. Less understood is how topical creams (those rubbed into the skin) can enter the bloodstream.
Topical creams have the same potential as prescription and standard OTC medications to interact with warfarin. While OTC products tend to lack the strength of prescription medications, patients typically are more liberal with their use feeling they carry less risk.
Products like hydrocortisone creams and topical pain relievers are common products that carry interaction concerns.
Over-the-counter products, like topical pain relief creams, can contain menthol and salicylates which have the potential to interact your warfarin medication. These ingredients are also found in most oral pain medications containing aspirin.1
Salicylates are plant hormones that are made into salicylatic acid, which is used as a preservative and commonly used in products like aspirin.2 Your INR test results may be influenced by topical pain relievers and aspirin-type products.3
You should consult with your doctor regarding the use of any over-the-counter medication or products.
Mark Crowther, Anne M. Holbrook, Renee Labiris. “Systematic Overview of Warfarin and Its Drug and Food Interactions”. Arch Intern Med/. vol 165. 2005.
A.S. Yip, W.H. Chow, Y.T. Tai, K.L. Cheung. Adverse effect of topical methylsalicylate ointment on warfarin anticoagulation: an unrecognized potential hazard. Postgrad Med J1990;66:367-369.
Bristol-Myers Squibb Company. Medication Guide for Coumadin Tablets and Coumadin for Injection [Package Insert]. Princeton, NJ: Bristol-Myers Squibb Company. 2007.