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Difference between first and second generation antihistamines? Why are 1st generation considered nonsedating?

3 doctors weighed in
Dr. Richard Wasserman
Internal Medicine - Allergy & Immunology
2 doctors agree

In brief: Sedation

1st generation are sedating because many people, up to 40%, get sleepy when taking them. 2nd generation antihistamines are chemically modified and are less likely to cause sedation.
The generics of the less sedating are cetirizine, fexafenadine, and loratidine. They cause sedation in some people, up to 11%, but much less than the older drugs.

In brief: Sedation

1st generation are sedating because many people, up to 40%, get sleepy when taking them. 2nd generation antihistamines are chemically modified and are less likely to cause sedation.
The generics of the less sedating are cetirizine, fexafenadine, and loratidine. They cause sedation in some people, up to 11%, but much less than the older drugs.
Dr. Richard Wasserman
Dr. Richard Wasserman
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