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Mt Plymouth, FL
A 32-year-old female asked:

How long does it take a 25mg benadryl (diphenhydramine) pill to start working on allergy?

2 doctor answers4 doctors weighed in
Dr. Manuel Lopez diaz
Emergency Medicine 28 years experience
25-45 min: It usually takes from 25 to 45 for a pill to start to make effect has to be dissolved and absorb into the blood stream to make effect.
Dr. Marsha Davis
Internal Medicine 28 years experience
Should: Start working within the hour. But it is a low dose and sedating. You might try an Allegra or Claritin (loratadine) ( store brand ok) that is once a day and once in your system you won't be on a roller coaster of it working or not as long as you take it regularly.

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Similar questions

A 46-year-old member asked:

How long does it take Benadryl (diphenhydramine) to get out of your system?

1 doctor answer2 doctors weighed in
Dr. Jeffrey Rumbyrt
Allergy and Immunology 32 years experience
4-6 hours: Typically, the effect of Benadryl (diphenhydramine) is 4-6 hours. It may be longer in people with liver disease.
Philippines
A member asked:

How long will benadryl (diphenhydramine) take effect?

1 doctor answer1 doctor weighed in
Dr. John Chiu
Allergy and Immunology 57 years experience
About an hour: It will take about an hour to take effect.

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Last updated Mar 25, 2018
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