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Diphenhydramine
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<p>Diphenhydramine, sold under the brand name <a href="/facts/Benadryl/WAWopCS7">Benadryl</a> among others, is an <a href="/facts/Antihistamine/HuMC25lt">antihistamine</a> and <a href="/facts/Sedative/JWzvq66P">sedative</a>. It is a <a href="/facts/H1_antagonist/L8azxq55">first-generation H1-antihistamine</a> and it works by blocking certain effects of <a href="/facts/Histamine/Vfjda665">histamine</a>, which produces its antihistamine and sedative effects. Diphenhydramine is also a potent <a href="/facts/Anticholinergic/9mDjo23r">anticholinergic</a>. It is mainly used to treat <a href="/facts/Allergy/dYAVosh8">allergies</a>, <a href="/facts/Insomnia/C1TnQTb2">insomnia</a>, and symptoms of the <a href="/facts/Common_cold/fP9A03U9">common cold</a>. It is also less commonly used for <a href="/facts/Tremor/rD6ogM7X">tremors</a> in <a href="/facts/Parkinsonism/orfkyX69">parkinsonism</a>, and <a href="/facts/Nausea/dyhkcbeD">nausea</a>. It is taken <a href="/facts/Oral_administration/vNQcvLVx">by mouth</a>, <a href="/facts/Injection_into_a_vein/AwwuD3Nu">injected into a vein</a>, <a href="/facts/Injection_into_a_muscle/PPNwW2wB">injected into a muscle</a>, or <a href="/facts/Topical_medication/alFfLndS">applied to the skin</a>. Maximal effect is typically around two hours after a dose, and effects can last for up to seven hours. </p><p>Common side effects include sleepiness, poor coordination, and upset stomach. There is no clear risk of harm when used during <a href="/facts/Pregnancy/vEKYGpep">pregnancy</a>; however, use during <a href="/facts/Breastfeeding/cdWXyYDX">breastfeeding</a> is not recommended. </p><p>It was developed by <a href="/facts/George_Rieveschl/rkDzsaGJ">George Rieveschl</a> and put into commercial use in 1946. It is available as a <a href="/facts/Generic_medication/IF6AXDVX">generic medication</a>, In 2022, it was the 258th most commonly prescribed medication in the United States, with more than 1 million prescriptions. </p><p>Its <a href="/facts/Sedative/JWzvq66P">sedative</a> and <a href="/facts/Deliriant/QVjeDyda">deliriant</a> effects have led to some cases of <a href="/facts/Recreational_drug_use/eoBD3vKn">recreational use</a>. </p>