Zyrtec Drug Warnings and Side Effects

Zyrtec is an over-the-counter medication used to relieve symptoms of seasonal allergies such as itching, sneezing, and runny nose. Zyrtec is the brand name for the drug cetirizine. It is available for adults and children over 2 years old.

A woman with allergies blowing her nose
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Active Ingredient


Dosage and Directions

Adults and children ages 6 to 64:

  • One (10 mg) tablet every 24 hours
  • One to two 5 mg chewable tablets every 24 hours depending on the severity of symptoms

Children ages 2 to 6 years old and adults over age 65:

  • One half (2.5 mg) to one (5 mg) teaspoon every 24 hours depending on the severity of symptoms

Children under 2 years old:

  • Ask a doctor


Zyrtec is used to relieve symptoms of seasonal allergies, hay fever, and hives which include:

  • Runny nose
  • Sneezing
  • Itchy eyes, nose or throat
  • Itchy rash (hives)

Side Effects

Although most people don't experience significant side effects with this medicine, some may occur. Possible side effects of Zyrtec include:

  • Drowsiness
  • Dry Mouth
  • Irritability
  • Loss of sleep
  • Sore throat
  • Stomach pain
  • Swelling

If any of these symptoms are severe or do not go away, contact your healthcare provider.

Certain side effects can be very serious. If you have any of the following after taking Zyrtec or cetirizine, seek medical advice immediately.

  • Symptoms of an allergic reaction such as hives, itching, skin rash, swelling of face, lips or tongue
  • Changes in vision or hearing
  • Fast heartbeat
  • High blood pressure
  • Infection
  • Trouble urinating or change in the amount of urine


If you have hives and experience difficulty breathing, significant swelling of the tongue or lips, wheezing, difficulty speaking or swallowing, dizziness, drooling, vomiting or loss of consciousness, seek emergency medical attention immediately. These are signs of a potentially life-threatening allergic reaction known as anaphylaxis.

Ask a Doctor Before Using Zyrtec 

If you have any of the following conditions, ask your healthcare provider before using Zyrtec:

  • You are allergic to Zyrtec, cetirizine, hydroxyzine, or any other medications.
  • You have liver disease.
  • You have kidney disease.
  • You are pregnant, plan to become pregnant or are breastfeeding.

Zyrtec is a great over the counter antihistamine and is generally very effective at relieving allergy symptoms. Some people try taking it for runny nose or congestion caused by colds and respiratory infections, but antihistamines typically don't work well against these illnesses.

If you have never taken Zyrtec or an antihistamine before, be aware that it could make you drowsy. Don't take it for the first time if you need to drive or work before you know how it will affect you.

This medicine is considered safe and effective for most people, but if you aren't sure or have questions about how it will work for you, talk to your healthcare provider before taking it. 

1 Source
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. De Sutter A, Saraswat A, van Driel M. Antihistamines for the common coldCochrane Database of Systematic Reviews. 2015. doi:10.1002/14651858.cd009345.pub2

Additional Reading

By Kristina Duda, RN
Kristina Duda, BSN, RN, CPN, has been working in healthcare since 2002. She specializes in pediatrics and disease and infection prevention.