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MA
A female asked:

how long does it take for benadryl to take effect?

1 doctor answer2 doctors weighed in
Dr. Charles Cattano
Gastroenterology 39 years experience
Some variables here: IV is faster than oral, but what dose and for what indication (sleep, rash, allergy, etc.) are you questioning please.

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Similar questions

CA
A 35-year-old member asked:

How quickly does Benadryl (diphenhydramine) start to work?

2 doctor answers3 doctors weighed in
Dr. Giana Nicoara
Allergy and Immunology 28 years experience
About 30 minutes: Lasts in the body for about 4-6 hours and then it needs to be redosed.
CA
A 36-year-old member asked:

How much Benadryl (diphenhydramine) is considered too much?

2 doctor answers4 doctors weighed in
Dr. Steven Machtinger
Allergy and Immunology 44 years experience
1 mg per 2 pounds: For children the correct dose is 1 mg/kg ( a kilogram is 2.2 pounds) every six hours as needed. Adults usually take 25-50 mg per dose. If you or your child need more than that you should consult your physician for advice. There are other drugs that are equally effective but cause less or no sedation and have fewer side-effects than Diphenhydramine (benadryl).
CA
A 33-year-old member asked:

Is frequent Benadryl (diphenhydramine) usage dangerous?

2 doctor answers4 doctors weighed in
Dr. Michael P Vaughn
Allergy and Immunology 34 years experience
No: There is a common misconception that frequent use of antihistamines leads to tolerance and eventual lack of effectiveness. This is untrue. Frequent use of decongestants that can lead to tachyphylaxis (lack of effect after several consecututive days of use) but there is no real justification for changing back and forth from Allegra to Claritin (loratadine) or to zyrtec. Typically if one works poorly, all will.
A 22-year-old female asked:

Is it safe to take benadrill while pregnaunt?

3 doctor answers6 doctors weighed in
Dr. Gaston Moran Celayes
Dr. Gaston Moran Celayesanswered
Internal Medicine 26 years experience
Yes: Fda classify the drug as class b. Medications in this category can be used safely. Avoid to use it in big doses, specially in third trimester.
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 16, 2021

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