Benefits and Side Effects of Hydroxyzine for Treating Allergies?

Hydroxyzine is a first-generation, sedating antihistamine, which has similar side effects to Benadryl. It is marketed under the brand names Atarax and Vistaril but is also available in generic form. Hydroxyzine was initially developed as a sedative during the 1950s but was found to have significant antihistamine properties.

This article explains how hydroxyzine works for treating allergies.

Woman blowing her nose into tissue
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Hydroxyzine for Allergies

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

Dosage

The dose of hydroxyzine depends on which condition you are using it to treat. However, a typical dose is 25 to 50 milligrams every six hours.

Hydroxyzine is also used for children, although the dose is calculated based on a child’s weight. However, keep in mind that the effects of sedation and drowsiness may make a prescription for one of the second-generation antihistamines such as Xyzal (levocetirizine) a better option.

How It Works

Hydroxyzine works by blocking the H1 receptor (histamine receptor), binding to them, thereby decreasing histamine activity.

What Is Histamine?

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

Histamine allows more fluid to escape from the capillaries into the tissues. When this occurs, you experience a runny nose and watery eyes. Histamine also causes swelling, rashes, and itching.

Side Effects

Hydroxyzine also 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 and Second Generation Antihistamines

The active metabolite (a kind of molecule that results from a metabolic process) of hydroxyzine is cetirizine (Zyrtec), which is available over-the-counter (OTC) as a low-sedating antihistamine.

The active isomer (two or more substances with the same molecular formula) of cetirizine is levocetirizine (Xyzal), which is available only by prescription and has become available in generic form. It doesn't cross into the brain as readily as hydroxyzine, and therefore it doesn't produce the same sedation. It also does not have the anti-anxiety effects of hydroxyzine for the same reason.

Zyrtec and Xyzal are better for treating allergic rhinitis than hydroxyzine since they have fewer side effects and a longer duration of action. They are also effective for treating hives and itching.

Zyrtec and Xyzal are ineffective for treating anxiety, insomnia, nausea, and vomiting, conditions for which healthcare providers prescribe hydroxyzine or other first-generation antihistamines. Despite hydroxyzine being a 50-year-old medication, it still benefits various medical conditions.

A review of studies of Xyzal (levocetirizine) in 2009 found that 5 mg/d effectively reduced hay fever and urticaria (hives) symptoms and improved quality of life.

Summary

Hydroxyzine is a first-generation antihistamine that treats allergies, hives, anxiety, and insomnia. It works by blocking H1 receptors to decrease histamine. As a first-generation medication, it causes sedation and drowsiness, which is helpful for short-term treatment of anxiety, insomnia, and nausea.

A Word From Verywell

If your allergies require medication, you should know that hydroxyzine is an option. However, keep in mind that it causes sedation and drowsiness. So, if you want to avoid that side effect, you may want to first try a second-generation antihistamine, like Zyrtec or Xyzal.

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4 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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  2. U.S. National Library of Medicine. PubChem. Hydroxyzine.

  3. Snidvongs K, Seresirikachorn K, Khattiyawittayakun L, Chitsuthipakorn W. Sedative Effects of Levocetirizine: A Systematic Review and Meta-Analysis of Randomized Controlled Studies. Drugs. 2017;77(2):175-186. doi:10.1007/s40265-016-0682-0

  4. Walsh GM. The anti-inflammatory effects of levocetirizine--are they clinically relevant or just an interesting additional effect?. Allergy Asthma Clin Immunol. 2009;5(1):14. doi:10.1186/1710-1492-5-14

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