Is Hydroxyzine Effective for the Treatment of Allergies?

First Generation Antihistamine

Hydroxyzine is a first-generation, sedating antihistamine, which means it 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 originally developed as a sedative during the 1950’s, but was found to have significant antihistamine properties.

Hydroxyzine for Allergies

Hydroxyzine is commonly prescribed for the treatment of various allergic conditions, particularly hives, but is also commonly used to treat itching, anxiety, insomnia, as well as nausea and vomiting.

The dose of hydroxyzine depends on the condition being treated, although a common 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, the effects of sedation and drowsiness may lead instead to a prescription for one of the second-generation antihistamines such as levocetirizine (Xyzal).

How Hydroxyzine Works for Allergies

Hydroxyzine works by blocking the H1 receptor, binding to them and decreasing the activity of histamine. Histamine allows more fluid to escape from the capillaries into the tissues, and it is this fluid you experience as a runny nose and watery eyes when you have an allergic reaction. Histamine also induces swelling and the production of wheals in rashes. This can help when itching (pruritis) is caused by allergies. By blocking the H1 receptor, hydroxyzine is effective against these allergy symptoms.

But hydroxyzine also crosses into the brain where it has further effects to cause drowsiness and sedation. These effects may not be wanted when treating allergies.

Second-Generation Antihistamines Derived from Hydroxyzine

The active metabolite of hydroxyzine is cetirizine (Zyrtec), which is available over-the-counter as a low-sedating antihistamine.

The active isomer 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 and anti-anxiety effects.

These medications are better for the treatment of allergic rhinitis than hydroxyzine, based on few side effects and longer duration of action, and are also effective for the treatment of hives and itching. Zyrtec and Xyzal are not effective for the treatment of anxiety, insomnia or nausea and vomiting. Despite hydroxyzine being a 50-year-old medication, it still has benefit for the treatment of various medical conditions.

A review of studies of levocetirizine in 2009 found that 5 mg/d was effective in reducing symptoms of seasonal allergic rhinitis, perennial allergic rhinitis, and chronic idiopathic urticaria, improving quality of life, with an acceptable tolerability profile.

An advantage of the second-generation antihistamines is the lack of unwanted side effects in such as sedation, drowsiness, and difficulty in concentrating and learning. These are especially concerns when school-aged children are treated for long periods with hydroxyzine.

Using levocetirizine (Xyzal) instead, there are no clinically relevant adverse effects on physical and psychomotor development in children aged six months to 12 years, according to studies.

Learn more about antihistamines.


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