This medication is an antihistamine, which is a category of medications that quickly suppresses some aspects of the body’s immune response, relieving allergy symptoms.

The drug has many medical uses, including as a pre-anesthesia sedative, and as an anti-anxiety treatment.

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

Hydroxyzine Uses

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

Urticaria (hives) Pruritus (itching) Anxiety Insomnia

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

How It Works

Hydroxyzine and similar allergy medications are called antihistamines because they block the activity of histamine, a chemical the body produces as part of your protective immune response.

People with allergies can have an overactive immune response to certain substances, resulting in allergy symptoms. 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.

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

Hydroxyzine vs. Other Antihistamines

Hydroxyzine is considered a first-generation sedating antihistamine. Newer allergy drugs, called second-generation antihistamines and third-generation antihistamines, are more selective in targeting the histamine receptors that are involved in allergic reactions. They are sometimes preferred over first-generation drugs like hydroxyzine.

Examples of antihistamines used for treating allergies:

Benadryl (diphenhydramine), a first-generation antihistamine, is a popular allergy medication that’s available OTC. The side effects of diphenhydramine and hydroxyzine are similar. Zyrtec (cetirizine), a second-generation antihistamine, is chemically similar to hydroxyzine but has much less of a sedative effect. It’s available OTC. Xyzal (levocetirizine) is a thrd generation antihistamine. It’s available only by prescription and in generic form. It doesn’t produce the same sedation as hydroxyzine.

Zyrtec and Xyzal cause fewer side effects than hydroxyzine, and they also work longer—24 hours, as compared to hydroxyzine’s 6 hours.

Zyrtec and Xyzal are not effective in treating anxiety, insomnia, nausea, and vomiting. Your healthcare provider may prescribe hydroxyzine or other first-generation antihistamines if you have these symptoms.

Before Taking

This medication is only available by prescription. Do not use hydroxyzine if you have ever had an allergic reaction or other adverse reaction to any form of this medication. Tell your healthcare provider if you have had any adverse reactions to other antihistamines.

If you have a heart condition, this medication might not be safe for you. If you are pregnant or planning to become pregnant, your healthcare provider might recommend that you avoid taking hydroxyzine.

Dosage

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

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

Side Effects

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

Common side effects:

DrowsinessDizzinessHeadachesDry mouthConstipation

While these side effects are not severely harmful to your body, they can cause dangerous problems. For example, you might be too drowsy to drive safely, or you could fall due to dizziness. It’s crucial that you wait to see your physical responses to hydroxyzine before you attempt any driving, operating machinery, or any activity that could be dangerous if you are dizzy.

Serious and less common side effects:

ConfusionTremorsSeizures

If you or someone else experiences any of these side effects, seek medical attention immediately.

Warnings and Interactions

This medication has many potential drug interactions. When picking up your prescription, talk to your pharmacist about all other medications that you take to find out if it is safe for you to take hydroxyzine along with your other medications.

Common drug interactions:

AlcoholAntidepressants Anti-anxiety medicationsAntihistaminesSedativesPain medications

Summary

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 in treating anxiety, insomnia, and nausea.

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