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What is Zyrtec for?

Zyrtec is a brand product that contains Cetirizine, which is a type of second generation antihistamine. Second generation antihistamines are typically non-drowsy, therefore a safer choice for people who need to drive or operate machinery. 


It is used to treat allergic conditions like hay fever and hives, as well as common cold symptoms like runny nose and itchiness.

How to use it?

Zyrtec is taken orally. Different starting doses are used in different age groups:

  • for children between 2-5 years old it is 2.5 mg once daily
  • for children between 6-11 years is 5 mg once daily
  • for adolescents between 12-17 years old and adults is 5-10 mg once daily.

What are the side effects of Zyrtec?

Although Zyrtec typically does not cause drowsiness at the usual dose, some people may still experience mild drowsiness.

Who should not take Zyrtec?

Pharmacist Tips:

  • Avoid alcohol use while taking this medication as it may cause more drowsiness.
  • Avoid driving or operating machinery until you know how you respond to Zyrtec.

Common dosing schedule: 

  • Zyrtec can be taken with or without food.

This schedule is for reference only, adjustments may be made according to individual needs.


Some common medications Zyrtec may interact with:

Please notify your doctor or pharmacist if you are taking the above medication, dosage adjustments might be needed.

Where to buy Zyrtec in Hong Kong?

In Hong Kong, Zyrtec is an over-the-counter medicine and can be purchased without a prescription from any retail outlet in Hong Kong. This includes grocery stores, convenience stores, medicine shops, and pharmacies. It can also be obtained from doctors. To find a pharmacy near you, refer to the list of pharmacies (“Authorized Sellers of Poisons”) from the Hong Kong Department of Health.


For more information about drug names and ingredients, you can visit Hong Kong’s Drug Office at https://www.drugoffice.gov.hk

Need more information?

For detailed information about the use of Zyrtec in children, pregnancy and breastfeeding, and for questions about drug interactions, please check with your pharmacist or doctor.

Disclaimer: our goal is to provide you with the most relevant drug information and common dosage for Hong Kong. This information does not constitute medical advice. For specific treatment recommendations and advice, always discuss with your doctor or pharmacist, and follow the instructions included with your specific medicine.

Available dosage
  • 1% (Oral Solution)
  • 10mg (Tablets)
Drug class
Sub class
Antihistamines (Second Generation)
Generic Names
Other drugs in same class
Used for: Seasonal allergic rhinitis, Urticaria
Chinese name:
Used for: Allergies, Hay fever, Urticaria
Chinese name:
Used for: Urticaria, Allergic conditions, Hay fever
Chinese name: