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A 17-year-old female asked:

My body acts weird. everytime i use zyrtec (cetirizine) drops i get very little drowsy only on the first dose. my tolerance goes away if i stop it for long. why?

1 doctor answer1 doctor weighed in
Dr. John Chiu
Allergy and Immunology 58 years experience
Expected: That's true with most sedating antihistamines. One does get used to the drowsiness after a couple of weeks. Whether this is due to a faster breakdown of the drug by the liver or reconditioning of the brain- no one knows However it is believed that some impairment in performance does happen when measured by performance tools even though you may not be feeling it.
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Last updated Nov 14, 2020


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