What is Zyrtec?

Zyrtec (cetirizine) is an antihistamine that reduces the effects of natural chemical histamine in the body. Histamine can produce symptoms of sneezing, itching, watery eyes, and runny nose.

Zyrtec is used to treat cold or allergy symptoms such as sneezing, itching, watery eyes, or runny nose.

Zyrtec is also used to treat itching and swelling caused by chronic urticaria (hives).

Zyrtec may also be used for purposes not listed in this medication guide.

Important information

Zyrtec may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert. Drinking alcohol can increase certain side effects of Zyrtec. Tell your doctor if you regularly use other medicines that make you sleepy (such as other cold or allergy medicine, narcotic pain medicine, sleeping pills, muscle relaxers, and medicine for seizures, depression, or anxiety). They can add to sleepiness caused by Zyrtec. Call your doctor if your symptoms do not improve, if they get worse, or if you also have a fever.

Before taking this medicine

You should not use Zyrtec if you are allergic to cetirizine.

Ask a doctor or pharmacist if it is safe for you to take this medicine if you have any medical conditions.

FDA pregnancy category B. Zyrtec is not expected to be harmful to an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant during treatment. Cetirizine can pass into breast milk and may harm a nursing baby. Do not use Zyrtec without telling your doctor if you are breast-feeding a baby.

See also: Pregnancy and breastfeeding warnings (in more detail)

Older adults may need to take a lower than normal dose. Follow your doctor’s instructions.

How should I take Zyrtec?

Use Zyrtec exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended.

You may take Zyrtec with or without food.

The chewable tablet must be chewed before you swallow it.

Do not swallow the Zyrtec dissolving tablet whole. Allow it to dissolve in your mouth without chewing. Swallow several times as the tablet dissolves. If desired, you may drink liquid to help swallow the dissolved tablet.

Measure liquid Zyrtec with a special dose-measuring spoon or cup, not a regular table spoon. If you do not have a dose-measuring device, ask your pharmacist for one.

Call your doctor if your symptoms do not improve, if they get worse, or if you also have a fever. Store this medicine at room temperature away from moisture and heat. Do not allow the liquid form of this medicine to freeze.

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention.

Overdose symptoms may include feeling restless or nervous, and then feeling drowsy.

What should I avoid?

Zyrtec may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert. Drinking alcohol can increase certain side effects of Zyrtec.

Zyrtec side effects

Get emergency medical help if you have any of these signs of an allergic reaction to Zyrtec: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have a serious side effect such as:

fast, pounding, or uneven heartbeat;
weakness, tremors (uncontrolled shaking), or sleep problems (insomnia);
severe restless feeling, hyperactivity;
confusion;
problems with vision; or
urinating less than usual or not at all.

Less serious Zyrtec side effects may include:

dizziness, drowsiness;
tired feeling;
dry mouth;
sore throat, cough;
nausea, constipation; or
headache.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects.

What other drugs will affect Zyrtec?

Tell your doctor if you regularly use other medicines that make you sleepy (such as other cold or allergy medicine, narcotic pain medicine, sleeping pills, muscle relaxers, and medicine for seizures, depression, or anxiety). They can add to sleepiness caused by Zyrtec.

This list is not complete and other drugs may interact with Zyrtec. Tell your doctor about all medications you use. This includes prescription, over-the-counter, vitamin, and herbal products. Do not start a new medication without telling your doctor.