Most meds I have taken in the past, the side-effects lasted 4 to 5 days. How long does drowsiness last from..

Question

Benadryl?

Answer 1

Benadryl, generically called Diphenhydramine, is a first generation antihistamine drug with an elimination half-life of 4 to 8 hours. You will feel the drowsiness most likely for about four to six hours, possibly up to twelve hours. Drowsiness is a side effect that should not be felt for more than a day. Some medications induce side effects that may last a while, regardless of short half-life. A good dose of an opiate/opioid, for instance, may constipte an individual for several days.

Answer 2

if taken prescribed dose then 8 hours.