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Tuesday, September 23, 2014
Pharmacy and Medications
When I have allergy like runny nose or hive fever, I take oral antihistamine. I wonder if topical antihistamin for mosquito bite like promethazine cream, benadryl cream or such like has the same mechanism of action or what. And why there is no such cream made from non-sedating antihistamine like Zyrtect or Claritin.
Topical creams containing diphenhydramine (Benadryl) and other antihistamines block histamine associated with bites or other local reactions, which is the same mechanism when you take them orally. The topical forms are not absorbed into the body in high enough levels to cause any sedation or other body-wide side effects. Because antihistamines that are normally sedating will not cause sedation when applied topically, there is no need to have non-sedating antihistamines used in topical products.
Michael Ganio, PharmD
Clinical Applications Pharmacist
Wexner Medical Center
The Ohio State University