Can You Overdose On Zyrtec (Cetirizine)?

In our latest question and answer, the pharmacist discusses whether or not it is possible to overdose on Zyrtec (cetirizine).


Is it possible to overdose on Zyrtec? Are there any side effects I should be aware of?

Asked by Jeremy On May 11, 2022

Answered by
Medical Content Reviewed By HelloPharmacist Staff

Published May 11, 2022
Last updated May 11, 2022

Key points

  • Like all drugs, it is possible to overdose on Zyrtec (cetirizine)
  • Taking over the recommended amount can increase the risk and severity of side effects such as dizziness, drowsiness, blurred vision, and constipation
  • It would take dosages far exceeding the maximum recommended amount to experience serious side effects, such as cardiovascular complications

Hello and thanks for reaching out!

Yes, it is possible to overdose on Zyrtec (cetirizine), just like any medication.

Fortunately,  it would take fairly high doses to experience significant side effects.

if you accidentally take an extra dose or two, the side effects are relatively mild and are generally not serious.

Overdose Cases

The prescribing information for Zyrtec notes two cases studies in which an overdose was observed in an adult and pediatric patient:

  • In one case study of an adult overdose, 150mg was taken (15 tablets) and only minimal effects were reported. It was noted that the patient was 'somnolent' (i.e. sleepy), but they did not display any other serious clinical signs of toxicity or abnormal blood chemistry.
  • An 18-month-old pediatric patient accidentally ingested 180 mg (18 tablets). No serious symptoms were reported aside from restlessness and irritability, followed by drowsiness.

The package insert for Zyrtec goes on to say the following regarding overdose:

"Should overdose occur, treatment should be symptomatic or supportive, taking into account any concomitantly ingested medications. There is no known specific antidote to cetirizine hydrochloride."

What Are The Effects Of A Zyrtec Overdose?

Although most case studies report minimal side effects in regard to overdosing with Zyrtec, it is important to note that some individuals may be more susceptible to side effects than others. It is therefore important to consider all of the side effects that Zyrtec can cause, such as:

  • Dry mouth
  • Dry eyes
  • Constipation
  • Drowsiness
  • Increased heart rate
  • Cardiac effects
  • Headache
  • Hyperventilation
  • Central nervous system excitation

In any case involving an overdose, it would be prudent to contact the poison control center at 1-800-222-1222 or go to the emergency room.

Animal Studies

There have been no deaths reported from Zyrtec overdose in humans and such studies have only been completed in mice and rats.

The prescribing information gives the following data regarding lethal doses in rodents:

  • The acute minimal lethal oral doses was 237 mg/kg in mice. For a 100-pound adult, this translates to over 10,000 mg (1,000-10 mg tablets).
  • The acute minimal lethal oral doses was 562 mg/kg in rats. For a 100-pound adult, this translates to over 25,000 mg (2,500-10 mg tablets).

Final Words

Based on the available information, and animal studies, it would take doses far exceeding the recommended daily dosage to experience serious side effects.

Nevertheless, taking more than directed does certainly increase the risk of them occurring.

Although many cases of overdose are accidental, know that assistance is available if you or someone you know has suicidal thoughts or has spoken about overdosing on medication. The National Suicide Prevention Lifeline hotline is 1-800-273-8255.


  • Cetirizine Prescribing Information, AccessFDA
  • Antihistamines and allergy, PubMed

About the Pharmacist

Dr. Brian Staiger, PharmD

Dr. Brian has been practicing pharmacy for over 11 years and has wide-ranging experiences in many different areas of the profession. From retail, clinical and administrative responsibilities, he's your knowledgeable and go-to source for all your pharmacy and medication related questions!

Recent Questions