# diphenhydramine

> English word · Noun · IPA /ˌdʌɪ.fɛnˈhʌɪ.dɹəm.iːn/ · frequency rank #88,276

## Definitions
1. An antihistamine and anticholinergic drug that blocks the effect of histamine at H₁ receptor sites, relieving allergy symptoms. It also reduces smooth muscle contraction, increases heart rate, and sedates the user by blocking muscarinic acetylcholine receptors (mAChRs).

## Etymology
From diphen(yl) + (benz)hydr(yl) + -amine.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/diphenhydramine