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Diphenhydramine Dosage
by Erowid

Diphenhydramine comes in different forms. The most common are various over-the-counter antihistamines, cold remedies and sleeping aids (including Benadryl, Sominex, Sleep-Eze D and several generic brands). Brands may contain different quantities of diphenhydramine, generally in the 25-50 mg per dose-unit (pill, capsule) range, as well as a variety of other potentially dangerous drugs. It is easy to mis-calculate dosages, so be careful and check to ensure that the product does not contain other dangerous active ingredients.

Diphenhydramine causes drowsiness, lethargy, and sleep even at doses recommended for anti-histamine use. The dosages below are reflective of recreational use where users take doses 4-20 times the recommended dose, stay awake, and try to enjoy the "drunken", delusional state.

Note: Some internet sources equate Diphenhydramine (Benadryl) and Dimenhydrinate (Dramamine). They are actually different chemicals, with different effects and dosage ranges.

The chart below shows approximate recreational dosages for pure diphenhydramine, measured in milligrams (mg).
Oral Diphenhydramine Dosages
Threshold10 mg
Light25-150 mg
Common150-300 mg
Strong250-500 mg
LD50 (Lethal Dose*)500 mg/kg in rats

Duration : 4 - 8 hours

* LD50 = dose which will kill 50% of the tested animals. It is difficult to extrapolate from animal data to human fatal doses, which would be much, much lower in this case.

* LD50 of 500 mg/kg in rats from Merck: "ld50 orally in rats (Gruhzit, Fisken)".

Acetaminophen Warning: Diphenhydramine products containing acetaminophen/paracetamol should not be used recreationally. High doses of acetaminophen can be fatal.

Diphenhydramine products containing other medicines can be harmful if taken in doses above the recommended limits. Dangerous interactions can occur.

  1. As with any powerful psychoactive substance, high doses are more likely to induce difficult experiences, negative side effects, allergic responses, etc.

Every individual reacts differently to every chemical.
Know your Body - Know your Mind - Know your Substance - Know your Source.

Erowid's dosage information is a summary of data gathered from users, research, and other
resources and should not be construed as recommendations. Individuals can respond
differently to the same dosage. What is safe for one can be deadly for another.

Start low with new substances.
Have trusted companion/guide/sitter/friend present and/or available.