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Can I take an antihistamine while on Coumadin? 

I am on Coumadin. Can I take "Wal-dryl" also? Other meds: Amiodrone, Biotin, metoprolol simvastatin, lisinopril and Primidone.
Thank you.

submitted by Paula from Port Neches, Texas on 12/03/2012


by St. Luke's Episcopal Hospital pharmacist, Stephen Michaud, PharmD, BCPS 

‘Wal-dryl’, with the active ingredient diphenhydramine [antihistamine], does not have any published drug interactions with warfarin. However, it does have published interactions with metoprolol.  Administration of diphenhydramine increases metoprolol levels moderately, so adding diphenhydramine (on a chronic basis) could be a problem; causing a slow heart and or low blood pressure. I would advise you speak to your cardiologist before taking ‘Wal-dryl’ or any other antihistamine.  

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Updated December 2012
Texas Heart Institute Heart Information Center
Through this community outreach program, staff members of the Texas Heart Institute (THI) provide educational information related to the prevention, diagnosis, and treatment of cardiovascular disease. It is not the intention of THI to provide specific medical advice, but rather to provide users with information to better understand their health and their diagnosed disorders. Specific medical advice will not be provided and THI urges you to visit a qualified physician for diagnosis and for answers to your questions.
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