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A 41-year-old member asked:

how fast should benadryl (diphenhydramine) work?

1 doctor answer5 doctors weighed in
Dr. Yash Khanna
Family Medicine 57 years experience
15 to 60 minutes: It start working within 15 to 60 minutes of ingestion.

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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 37-year-old member asked:

How much Benadryl (diphenhydramine) and beer would knock you out completely?

1 doctor answer2 doctors weighed in
Dr. Kevin Nasky
Psychiatry 16 years experience
Depends: That depends on several factors: your tolerance to alcohol, your sensitivity to antihistamines, your present level of sleepiness, whether or not you've ingested any stimulants, etc. I assume you're looking to a benadryl/alcohol combination to help you sleep? If so, that is a bad idea. The resulting sleep quality would be terrible, and you'd awaken feeling unrested (or worse!) talk to your doc.
A 32-year-old member asked:

How much diphenhydramine do people take to trip?

2 doctor answers2 doctors weighed in
Dr. Shalabh Bansal
Pediatrics 13 years experience
Toxicity: Every human body reacts to a drug differently. In some children, even one dose of Benadryl (diphenhydramine) will make them very hyper (known as a paradoxical reaction). First and foremost, you should always follow the labeled instructions on all otc medications. If still unsure, speak to your physician.

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Last updated Mar 11, 2018
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