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Are "24-Hour Hives" Antihistamines Different Than Regular Ones?

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I've seen new antihistamines brands labeled "hives" that say they work for 24-hrs to relieve hives. Are these different from the "regular" version of the same antihistamine?

No, that is marketing information on the label. There are not different “forms” of the same antihistamines. For example, there is a group of common antihistamines that work for 18 - 24 hours. They are also called “second-generation” antihistamines. Common ones are:

  • Zyrtec (Cetirizine)
  • Allegra (Fexofenadine)
  • Claritin (Loratadine)

There aren’t different “forms” of these medications with different “lengths of action.” These drugs are different from Benadryl (Diphenhydramine) that works for four to six hours. Compared to Benadryl, second-generation antihistamines have fewer side effects (e.g., drowsiness).

Finally, antihistamines help control rashes and itching due to hives. They help with common allergy symptoms. This includes itching, sneezing, and runny nose, among others.

Allergy, Hives (Urticaria), Medicines
Answered by

John M. James, MD, is a board-certified allergist. He is also President of Food Allergy Consulting and Education Services, LLC. He has worked as a medical specialist in the field of allergy, asthma, and immunology for over 30 years. Dr. James received his bachelor’s degree from the University of Arkansas and his Doctor of Medicine degree from the University of Tennessee. He is board certified by the American Board of Allergy and Immunology.

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