Does Tagamet (Cimetidine) Work For Allergies?

In our latest question and answer, the pharmacist discusses whether or not Tagamet (cimetidine) can be used to treat allergies.


I take Allegra for idiopathic hives which are worse this spring season than usual. My MD suggested I take Tagamet in addition to treat my hives? Why? Also would generic cimetidine work as well? I also take Advair 250/50 for asthma. Thank you for any advice you can offer.

Asked by annee On May 26, 2018

Answered by
Medical Content Reviewed By PharmacistAnswers Staff

On May 30, 2018

Woman ItchingTagamet (Cimetidine) is classified as a H2-blocker (i.e. H2-receptor antagonist) and is most commonly used in the treatment of ulcers, gastroesophageal reflux disease (GERD) and heartburn. Although it blocks different histamine receptors than H1 blockers, like Allegra and Benadryl, Tagamet has been shown to reduce the severity of certain allergy symptoms, most notably skin reactions like hives.

Tagamet is often recommended to be used in conjunction with traditional antihistamines, like Allegra, for better relief.  One study found that when Tagamet (Cimetidine) was used with Benadryl (diphenhydramine), it was more effective in the treatment of hives caused by an allergic reaction, than an antihistamine alone.  Many doctors feel that by blocking histamine from both H1 and H2 receptors, a better, more complete response will be seen by the patient.  

In addition, there doesn't seem to any drawback to at least trying to use a H2 blocker like Tagamet with a traditional H1 blocker as the risk of side effects does not appear to increase. Most studies suggest a dose of Tagamet (cimetidine) at 400 to 800 mg by mouth twice daily. Different H2 blockers are an option as well, which include Pepcid (famotidine) 20 mg by mouth twice daily or Zantac (ranitidine) 150 to 300 mg by mouth once or twice daily.

Cimetidine, as the generic to Tagamet, will work as well as the brand name Tagamet.  All generic drugs must undergo testing to prove that they are equivalent to the brand name drug.  There should be no issues taking the generic medication.

About the Pharmacist

Ms. Jennifer Hauder RPh

Jennifer Hauder is a registered pharmacist in the state of Illinois. She has over 10 years experience as a pharmacist in the retail and pharmacy benefit managers (PBM) settings. She became a pharmacist due to her interest in healthcare and the opportunity to help others with their healthcare needs. When not working, she enjoys spending time with her husband, three children and two black labs Lucky and Charms.

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