Warfarin With Benadryl Interaction

In our latest question and answer, the pharmacist discusses taking Benadryl with warfarin.


Does Benadryl have any interactions with any drugs? What allergy medicine would you recommend for someone taking warfarin?

Asked by Cathy On Apr 16, 2019

Answered by
Medical Content Reviewed By PharmacistAnswers Staff

On Apr 16, 2019
Benadryl Box with text - Benadryl with warfarin interaction


There is no known interaction between Benadryl (diphenhydramine) and warfarin. They are considered safe to take together.[1]

In fact, as it concerns over the counter allergy medication, most are safe to take with warfarin since they don't interact with it and don't affect blood coagulation on their own.

OTC Warfarin Interactions

It is always a good idea to look into potential drug interactions, even with over the counter drugs, if you are taking a blood thinner like warfarin.

Not only do some drugs have blood thinning properties on their own (like NSAIDs), many are known to either increase or decrease warfarin concentrations in the blood which can significantly alter its effects.[2]

If warfarin concentrations are increased via a drug interaction, there is an increased risk of serious bleeds.

If warfarin concentrations are decreased via a drug interaction, it may not be as effective, putting you at risk for blood clots.

There are several over the counter medications that you need to be aware of if you take warfarin, including:[3]

  • Aspirin
  • Ibuprofen
  • Naproxen
  • St. John's Wort
  • Red years rice
  • Pepto-Bismol (Bismuth Subsalicylate)
  • Pepcid
  • Prilosec
  • Zantac

Fortunately, OTC allergy medications are not known to interact with warfarin. All of the following should be safe to take with it:

  • Claritin (loratadine)
  • Allegra (fexofenadine)
  • Zyrtec (cetirizine)
  • Benadryl (diphenhydramine)
  • Xyzal (levocetirizine)
  • Chlor-Trimeton (chlorpheniramine)

If you are suffering from allergies and looking for an allergy medication for relief, you can feel safe taking them with warfarin.

Which allergy medication you choose to take should depend on what you are looking for.

Second-generation antihistamines (like Allegra and Claritin) are non-drowsy and last around 24 hours per dose. They are a good option for all-day allergy relief.

If you are looking for something sedating, Benadryl and Chlor-Trimeton would be options and can help you fall asleep at night.


There is no known interaction between Benadryl (diphenhydramine) and warfarin.

  1. ^ Elsevier ClinicalKey: Warfarin Monograph. ClinicalKey
  2. ^ Drug interactions with warfarin: what clinicians need to know. PubMed
  3. ^ Prescribing Warfarin Appropriately to Meet Patient Safety Goals. PubMed

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