Allergies Home > Benadryl
Benadryl is an antihistamine product that is available both by prescription and over the counter. It can be used for a variety of different uses (depending on the particular product), including relieving or preventing allergy symptoms, treating common cold symptoms, and causing drowsiness. The medication comes in various forms; it can be taken by mouth, applied to the skin, or injected into a vein or muscle.
What Is Benadryl?
Benadryl® (diphenhydramine hydrochloride) is an antihistamine medication available both over the counter and with a prescription. It comes in many different forms and is used for a variety of different purposes.
(Click Benadryl Uses for more information, including possible off-label uses.)
Who Makes This Medication?
Brand-name Benadryl is made by McNeil Consumer Healthcare, while other versions of diphenhydramine (including other brand-name medications or generic medications) are made by various other manufacturers.
How Does Benadryl Work?
Benadryl is part of a class of drugs called antihistamines. Specifically, it is an H1 receptor antagonist. This means that it blocks a specific type of histamine receptor in the body (known as H1 receptors). Since allergic reactions are partly caused by the release of histamine from certain cells in the body, this drug can help relieve or prevent allergy symptoms.
Benadryl 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 other purposes (such as for Parkinson's disease or for relieving a runny nose due to the common cold).
Like many antihistamines, Benadryl also works as a sedative. This action has made the medication useful as a sleep aid but also limits the usefulness of the medication for other uses (since drowsiness can be a bothersome side effect).