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A member asked:
What are long term side effects of diphenhydramine antihistamines and do they lose effectiveness over time? k
A doctor has provided 1 answer
Minimal: Diphenhydramine is the active ingredient in Benadryl (diphenhydramine) and has been around for a very long time. Like most antihistamines, there is not believed to be long term side effects. Losing effectiveness is less well studied, but with ongoing use there could be some development of tolerance or it could be that you are still being exposed to an allergen and that is why symptoms are not controlled.
Answered 12/30/2016
5.4k views
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