Generic name: Cetirizine.

Zyrtec is a nonsedating antihistamine. Antihistamines block the effects of histamine, a body chemical that causes swelling and itching. 

Quick Facts About Zyrtec


Used to relieve hay fever and its symptoms: itchy, runny nose, sneezing, and itchy, watery eyes. Also used to relieve year-round allergies due to dust, mold, and animal dander; and chronic itchy skin and hives.

Zyrtec Dosage

Take exactly as prescribed, with or without food.

  • Usual adult dose: 5 to 10 milligrams once per day.
  • Usual child dose: not prescribed for children under 12 years.
  • Missed dose: take as soon as possible, unless almost time for next dose. In that case, do not take missed dose; go back to regular schedule. Do not double doses.

Zyrtec Side Effects

Overdose symptoms:

extreme sleepiness. If you suspect an overdose, immediately seek medical attention.

More common side effects: drowsiness, dry mouth, fatigue.

Less common Zyrtec side effects: dizziness, sore throat.


Drug interactions are rare.

Inform your doctor before combining Zyrtec with:

antidepressants such as Anafranil, Elavil, and Tofranil; muscle relaxants such as Valium and Soma; pain-relieving narcotics such as codeine, Demerol, and Percocet; sedatives such as Nembutal, Seconal, and phenobarbital; sleeping pills such as Halcion, Restoril, and Ambien; theophylline (Theo-Dur).

Do not combine this medication with alcohol; may intensify the effects of alcohol.

Special Cautions

Effects of Zyrtec on pregnant women and nursing mothers not known. If pregnant, planning to become pregnant, or breastfeeding, inform your doctor immediately. Potential benefits may justify the potential risk in using the medication.

No special precautions apply to seniors.

Not prescribed for children under 12 years.

  • Take only for allergies, unless otherwise advised by your doctor.
  • Lower dosage may be prescribed if you have kidney or liver disease.
  • May impair your ability to drive a car or operate machinery. Do not take part in any activity that requires alertness until adjusted to medication.


HealthSurvey.org provides accurate and independent information prescription pills, over-the-counter medicines and natural products. This material is provided for educational purposes only and is not intended for medical advice, diagnosis or treatment. If you have questions about  dosage, or Zyrtec side effects, please contact your healthcare provider.