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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
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