What Is Diphenhydramine?
Many people may wonder, "What is diphenhydramine?" Diphenhydramine (Benadryl®, Sominex®, and many others) is an antihistamine medication that is used for a variety of different purposes, most commonly for the treatment of allergy symptoms and insomnia.
The medication comes in many different forms; depending on the particular product, it may be taken by mouth, applied to the skin, or injected into a vein or muscle. Some products are available by prescription only, but others can be found over the counter. Most oral diphenhydramine products can be used in children ages six and older, while topical forms of the drug can be given to children as young as two.
Diphenhydramine works by blocking H1 receptors in the body. Since allergic reactions are partly caused by the release of histamine from certain cells in the body, diphenhydramine can help relieve or prevent allergy symptoms. The medication also blocks acetylcholine receptors, an action which produces some of the bothersome side effects of the medication (such as dry mouth or difficulty urinating) but also makes the drug useful for some uses (such as for Parkinson's disease or for relieving a runny nose due to the common cold).
(Click Diphenhydramine for more information on what diphenhydramine is used for, to learn about the effects of this medicine, and to find out what side effects may occur with the drug.)