What Is Diphenhydramine Used For?
How Does It Work?
Diphenhydramine 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, diphenhydramine can help relieve or prevent allergy symptoms.
Diphenhydramine 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 purposes (such as for Parkinson's disease or for relieving a runny nose due to the common cold).
Like many antihistamines, diphenhydramine 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).
What Is Diphenhydramine Used for in Children?
Oral children's diphenhydramine products are approved for treating allergies (such as hay fever) in children ages six years and older. Adult diphenhydramine oral products are approved for treating allergies or cold symptoms in children ages six years and older. Topical (skin) products are approved for use in children two years old and older.
Diphenhydramine is usually not recommended as a medication to make a child drowsy. Not only can this practice be dangerous, but it is often ineffective. In fact, diphenhydramine can have an opposite effect on children, sometimes making them hyperactive.
On occasion, your healthcare provider may recommend diphenhydramine for something other than the approved uses (this would be known as an "off-label" use). Off-label uses of diphenhydramine include the treatment of the following conditions:
- Morning sickness (see Diphenhydramine and Pregnancy)
- Attention deficit hyperactivity disorder (ADHD)
- Extrapyramidal symptoms due to antipsychotic medications and other medications.
Diphenhydramine is also used off-label for preventing negative reactions to certain cancer medications.