Can You Take Benadryl With Pepcid (Famotidine)?
In our latest question and answer, the pharmacist discusses whether or not there is an interaction between Benadryl (diphenhydramine) and Pepcid (famotidine).
Is it safe to use Pepcid and Benadryl together?
Aug 30, 2022- Benadryl and Pepcid are safe to take together as they work on different histamine receptors with no known drug interaction. Benadryl blocks H1 receptors to treat allergies and can cause drowsiness, while Pepcid blocks H2 receptors in the stomach to reduce acid. Combining H1 and H2 blockers may even be effective for treating certain types of itching that don't respond well to antihistamines alone.
Answer
There is no known drug interaction between Pepcid (famotidine) and Benadryl (diphenhydramine). They are considered safe to take together.
Although they both work on histamine receptors, they do so on different ones. Antihistamines like Benadryl block 'H1' receptors, while drugs like Pepcid, Zantac and Tagamet block 'H2' receptors, which play a role in stomach acid secretion.
There is even some evidence that combining 'H1' and 'H2' blockers can be effective for treating itch not otherwise well-controlled with antihistamines alone.
About Benadryl (Diphenhydramine)
Benadryl is a first-generation antihistamine that is most commonly used to treat allergic reactions. It blocks the binding of histamine to H1 receptors. One of the most commonly seen side effects of this medication is sedation and drowsiness which is why Benadryl is commonly used as a sleep aid. A few of the other commonly seen side effects include:
- Constipation
- Urinary retention
- Blurred vision
Each dose of Benadryl lasts around 4 to 6 hours after taking by mouth.
About Pepcid (Famotidine)
Pepcid also blocks the binding of histamine, but it does so specifically in the stomach, at different receptors (H2), to lower the acidity of the stomach and help with symptoms of heartburn or acid reflux.
Because of the histamine blocking that this medication provides, it can also be used as an adjunctive treatment for patients who are experiencing allergic reactions. It is not as effective as Benadryl, but it can be used to help bolster the response.
References & sources
Glossary — Terms in This Answer
- Drug interaction
- A situation where two medications affect each other's effectiveness or safety when taken together.
- Histamine receptors
- Specific binding sites on cells where histamine molecules attach to trigger various body responses.
- Antihistamines
- Medications that block histamine from attaching to its receptors, reducing allergic reactions and other histamine-related symptoms.
- H1 receptors
- A type of histamine receptor found throughout the body that triggers allergic reactions and other responses when activated.
- H2 receptors
- A type of histamine receptor found mainly in the stomach that controls acid secretion when activated.
- First-generation antihistamine
- An older class of antihistamine medication that can cross into the brain and commonly causes drowsiness.
- Acid reflux
- A condition where stomach acid flows backward into the esophagus, causing heartburn and discomfort.
- Adjunctive treatment
- An additional medication or therapy used alongside a primary treatment to enhance effectiveness.
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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