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A 40-year-old member asked:

How long does benadryl (diphenhydramine) keep you drowsy?

1 doctor answer1 doctor weighed in
Dr. Joseph O'Bryan
Family Medicine 28 years experience
Benadryl (diphenhydramine): Most people it will last 8 hours or so but I have seen people who still feel groggy 12 hours later or more

Similar questions

A 37-year-old member asked:

How long does it take for Benadryl (diphenhydramine) to make you drowsy?

1 doctor answer2 doctors weighed in
Dr. Tammi Schlichtemeier
Pediatrics 32 years experience
About 45 minutes: Benadryl (diphenhydramine) can make some people drowsy. The maximum effect occurs in about 45 minutes or so. However, it can result in hyperalertness in some people.
A 29-year-old member asked:

How long does drowsiness generally last after a benadryl (diphenhydramine)?

1 doctor answer1 doctor weighed in
Dr. Anthony Rooklin
Allergy and Immunology 50 years experience
Four to six hours: The half life of Benadryl (diphenhydramine) is about four to six hours and usually the sedation will wear off within that time frame. As one continues to use it often a certain amount of tolerance develops and less sedation is appreciated. Studies have shown that its effect on brain function still continues despite less sedation.

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Last updated Apr 28, 2018
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