Hydroxyzine for Allergies: Is It Effective?

Also known as Vistaril

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Hydroxyzine is a medication used for allergies. It is sold under the brand name Vistaril and it’s also available in generic form.

The drug was initially developed in the 1950s as a sedative, but it was later found to work as an antihistamine (allergy drug). Hydroxyzine is considered a first-generation sedating antihistamine. It has similar side effects to Benadryl (diphenhydramine), which is a more popular allergy medication.

This article explains how hydroxyzine works for treating allergies and how it compares to newer antihistamines.

Woman blowing her nose into tissue
JGI/Tom Grill / Getty Images

Hydroxyzine Uses

Healthcare providers commonly prescribe hydroxyzine for the treatment of various allergic conditions and other illnesses, including:

A hydroxyzine formulation for intramuscular injection is sometimes used to control nausea and vomiting.

Hydroxyzine and similar allergy medications are called antihistamines because they block the activity of chemicals called histamine.

What Is Histamine?

Histamine is a chemical the body produces to protect you from harmful substances. However, in people with allergies, histamine overreacts when exposed to allergens, resulting in allergy symptoms.

How Hydroxyzine Works

Hydroxyzine works by blocking H1 (histamine) receptors and binding to them, leaving fewer places for histamine to latch onto. This decreases overall histamine activity.

Histamine allows excess fluid to escape from the capillaries (small blood vessels) into the tissues. That’s what causes a runny nose and watery eyes. Histamine also causes swelling, rashes, and itching.


The dose of hydroxyzine depends on which condition you’re using it for. However, a typical dose is 25 or 50 milligrams (mg) every six hours.

Hydroxyzine is also used for children, although the dose is based on a child’s age.

Side Effects

Hydroxyzine crosses into the brain, where it can cause drowsiness and sedation. These effects may be beneficial for treating anxiety and insomnia. However, they may be unwanted when treating allergies.

Hydroxyzine vs. Other Antihistamines

Newer allergy drugs, called second-generation antihistamines, are generally preferred over first-generation drugs like hydroxyzine.

Zyrtec (cetirizine) is chemically similar to hydroxyzine but has much less of a sedative effect. It’s available over-the-counter (OTC).

A similar drug is Xyzal (levocetirizine). It’s available only by prescription but has become available in generic form. Like Zyrtec, it doesn’t produce the same sedation as hydroxyzine.

Zyrtec and Xyzal are better than hydroxyzine for treating allergies, hives, and itching. In part, that’s due to their causing fewer side effects. However, they also work longer—24 hours, as compared to hydroxyzine’s 6 hours.

However, Zyrtec and Xyzal are ineffective for treating anxiety, insomnia, nausea, and vomiting—for which healthcare providers may still prescribe hydroxyzine or other first-generation antihistamines.

Hydroxyzine vs. Benadryl

Hydroxyzine and Benadryl are both sedating, first-generation antihistamines. Which one works better may depend on who is taking it and why. Your healthcare provider can help you decide which is best for you.


Hydroxyzine is a first-generation sedating antihistamine that treats allergies, hives, anxiety, and insomnia. It works by blocking H1 receptors to decrease histamine activity.

The drug’s sedative effects can be helpful for treating anxiety, insomnia, and nausea.

Hydroxyzine isn’t as effective at treating allergies as second-generation antihistamines such as Zyrtec and Xyzal, which aren’t sedating.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Daniel More, MD
Daniel More, MD, is a board-certified allergist and clinical immunologist. He is an assistant clinical professor at the University of California, San Francisco School of Medicine and currently practices at Central Coast Allergy and Asthma in Salinas, California.