Is There An Interaction Between Warfarin and Benadryl?
In our latest question and answer, the pharmacist discusses taking Benadryl with warfarin.
Does Benadryl have any interactions with someone taking warfarin?
Aug 24, 2022- Benadryl and warfarin are safe to take together with no known interaction between them. Most over-the-counter allergy medications do not interact with warfarin or affect blood clotting. You should always check with your pharmacist about potential interactions with other over-the-counter medications when taking warfarin, as some drugs like NSAIDs and others can increase bleeding risk or reduce warfarin's effectiveness.
Answer
There is no known interaction between Benadryl (diphenhydramine) and warfarin. They are considered safe to take together.
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
Even though warfarin doesn't interact with OTC allergy medications, there are some drugs you need to be cautious with that you can get without a prescription. 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.
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:
- Aspirin
- Ibuprofen
- Naproxen
- St. John's Wort
- Red yeast rice
- Pepto-Bismol (Bismuth Subsalicylate)
- Pepcid
- Prilosec
- Zantac
Fortunately, as mentioned, 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)
Final Words
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.
References & sources
Glossary — Terms in This Answer
- Diphenhydramine
- The active ingredient in Benadryl, an antihistamine medication used to treat allergies and itching.
- Warfarin
- A blood thinner medication that prevents blood clots by reducing the blood's ability to coagulate.
- Drug interactions
- When two or more medications affect each other's effectiveness or safety when taken together.
- Blood coagulation
- The process of blood thickening and clotting to stop bleeding.
- NSAIDs
- Non-steroidal anti-inflammatory drugs like ibuprofen and naproxen that can thin the blood and increase bleeding risk.
- Antihistamines
- Medications that block the effects of histamine to relieve allergy symptoms like itching and sneezing.
- Blood clots
- Solid clumps that form when blood thickens abnormally, which can block blood vessels and cause serious health problems.
- Second-generation antihistamines
- Newer allergy medications like Allegra and Claritin that are less likely to cause drowsiness than older versions.
Dr. Brian Staiger, PharmD
Doctor of Pharmacy, board certified clinical pharmacist (BCPS), American Herbalist Guild, Medication Therapy Management certified
Brian Staiger, PharmD, BCPS, is a licensed pharmacist with more than 13 years of experience across retail pharmacy, clinical pharmacy, medication safety, pharmacy program development, and healthcare administration. He is the founder of HelloPharmacist.com, where he helps patients...
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