Using Zyrtec for Treating Hives and Allergies

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Zyrtec (cetirizine) is an over-the-counter antihistamine used to treat hives (urticaria) and seasonal allergies (allergic rhinitis, or hayfever).

Zyrtec is in the class of drugs referred to as second-generation antihistamines. It is recommended for children 2 years of age and older and for adults. It is available as a tablet that can be swallowed, as a chewable tablet, and as a liquid.

This article explains how Zyrtec works for treating hives and seasonal allergies, its potential side effects, and how it compares to other antihistamines.

A man's legs covered in an allergic reaction
Lode Kuylenstierna / EyeEm / Getty Images

Zyrtec Uses

Zyrtec is approved for the treatment of hives and symptoms of allergic rhinitis such as sneezing, runny nose, and itchy eyes.

How It Works

Zyrtec and other antihistamines work by blocking histamines to reduce symptoms.

When you have an allergic reaction to something, your body releases histamines into your blood. Histamines are chemicals produced when the immune system mistakenly responds to an allergen as an invader.

When you take an antihistamine, it reverses your body's reactions and prevents hives, sneezing, itchy eyes, and wheezing.

Zyrtec vs. Other Antihistamines

First-generation antihistamines include medications such as Benadryl (diphenhydramine) and Vistaril/Atarax (hydroxyzine). These medications can be very effective for the treatment of hives or allergies but usually cause significant drowsiness.

In addition to Zyrtec, other second-generation antihistamines include Xyzal(levocetirizine), Claritin(loratadine), and Allegra (fexofenadine).

Zyrtec can be a good choice for allergies and hives, though it can cause sedation and fatigue in some people. These symptoms are usually milder than with the first generation antihistamines, but more pronounced than with medications such as Claritin or Allegra.

Overall, Zyrtec appears to be more effective for controlling allergies than Claritin or Allegra, but similar to Xyzal. However, every person with allergies is different, and it's often impossible to predict which medication will work best for any one person.

Multiple studies show that Zyrtec is better at treating hay fever and hives when compared to Claritin (loratadine) or Allegra (fexofenadine). Zyrtec works faster, is more effective, and lasts longer than these other antihistamines.

When used for hives, Zyrtec may work better than Claritin or Allegra but is similar in effectiveness to Xyzal (levocetirizine) and Clarinex (desloratadine). Zyrtec, however, is more likely than Claritin or Allegra to have the side effect of fatigue.

Before Taking Zyrtec

Your allergist or healthcare provider can advise you on the best antihistamine for you. Some people try different medications while keeping an allergy journal as a way to see which medication works best for them specifically.

With children, it's important to weigh the benefits of treatments (reduction of symptoms) against the possible risks and side effects, such as drowsiness. Your pediatrician can help you find the best antihistamine for your child.

Zyrtec During Pregnancy

During pregnancy, those with allergic rhinitis or hives may notice a worsening of their symptoms, an improvement, or things may stay the same.

Zyrtec has a pregnancy category "B" rating, meaning that it is generally considered to be safe during pregnancy. In contrast, some allergy medications should usually be avoided during pregnancy including intranasal antihistamines and first-generation antihistamines (such as Benadryl).


The standard dosage of Zyrtec is 2.5 milligrams (mg)—which is equivalent to 1/2 teaspoon—for children 2 to 6 years of age, and 5-10 milligrams for those aged 6 years and older. Larger doses have not been shown to be more beneficial for the treatment of hay fever, but may be more useful for the treatment of hives in some people.

Zyrtec starts to work within an hour or so after taking the medication—making it useful for the as-needed treatment of hay fever and hives. Taking it daily, however, may result in better overall control of allergy symptoms. This is in contrast to some medications, particularly nasal steroid sprays, which need to be taken for some time to be effective.

Side Effects

Zyrtec has a low incidence of side effects and is usually well-tolerated. Common side effects include:

  • Sedation
  • Fatigue
  • Dizziness
  • Dry mouth

Warnings and Interactions

It is possible to have an allergic reaction to Zyrtec. Symptoms include swelling, hives, difficulty breathing, a bloody nose, or wheezing. If any of these symptoms occur, seek medical attention right away.

Other possibilities are a stomach ache, irritability in small children, headache, and diarrhea. Call your healthcare provider if you experience any of these.

Avoid taking Zyrtec if if you have ever had an allergic reaction to it or any of its ingredients, or to an antihistamine containing hydroxyzine. It's important to avoid alcohol and sedatives when taking Zyrtec.


Zyrtec is an over-the-counter antihistamine that is used to relieve hives and symptoms of allergic rhinitis. It is in a class of drugs known as second generation antihistamines. These typically have fewer side effects than first generation antihistamines (such as Benadryl) and are considered preferable in most circumstances.

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.
  1. Fein MN, Fischer DA, O'Keefe AW, Sussman GL. CSACI position statement: Newer generation H1-antihistamines are safer than first-generation H1-antihistamines and should be the first-line antihistamines for the treatment of allergic rhinitis and urticariaAllergy Asthma Clin Immunol. 2019;15:61. Published 2019 Oct 1. doi:10.1186/s13223-019-0375-9

  2. National Library of Medicine. Daily Med. Zyrtec Allergy: cetirizine hydrochloride tablet, film coated.

  3. Asthma & Allergy Network. Pregnancy and allergies.

  4. National Library of Medicine. MedlinePlus. Hives.

  5. American Academy of Asthma Allergy & Immunology. If/when are first generation antihistamines advantageous over newer ones?

  6. Zyrtec. Dosage guide.

Additional Reading

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.