Skip to main content
An official website of the United States government
NIH Websites Are Changing
Per Executive Order 14434, federal agencies are now using "Super Intelligence" (SI) in place of "Artificial Intelligence" (AI). You may see both terms across NIH content during this transition.

diphenhydramine

A first generation antihistamine and ethanolamine with sedative and anti-allergic properties. Diphenhydramine competitively inhibits the histamine-1 (H1) receptor, thereby alleviating the symptoms caused by endogenous histamine on bronchial, capillary and gastrointestinal smooth muscles. This prevents histamine-induced bronchoconstriction, vasodilation, increased capillary permeability, and GI smooth muscle spasms.
Check for active clinical trials using this agentView this agent in the NCI Thesaurus
Synonym:Probedryl
Rigidyl
US brand name:Syntedril
Code name:FAR 90X2
PM 255
S51
Chemical structure:2-(diphenylmethoxy)-N,N-dimethylethylamine
O-benzhydryldimethylaminoethanol
Search NCI's Drug Dictionary
Please enter up to 30 characters for your search