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Dr Roger Henderson
Reviewed by Dr Roger HendersonReviewed on 13.10.2023 | 2 minutes read

Cetirizine is a non-drowsy antihistamine, available from any pharmacy. Adults and children can relieve symptoms of a range of allergies, including pollen (hay fever), dust, animal dander, or in response to insect bites. It can also calm contact dermatitis and atopic eczema.

Cetirizine relieves itching, sneezing, a runny nose, skin rash and eye symptoms such as feeling red, itchy or watery. It is available in tablet, capsule and oral liquid forms. Some examples of branded versions of cetirizine include Allacan, Piriteze and Zirtek.

Even though cetirizine is classed as a non-drowsy antihistamine, it can still cause drowsiness in some people. If you do experience drowsiness, it is advised that you avoid driving or drinking alcohol.

How much should I take?

For adults and children over 12, cetirizine should be taken as a once-daily dose, unless directed differently by your doctor. Tablets come as a standard 10mg dose (or 10ml of liquid).

Doses for children are determined by age group, and this is given as a liquid. They can take this twice daily. It's suitable for children over the age of two years.

How does it work?

During an allergic reaction your immune system releases a chemical called histamine, which is responsible for the symptoms of an allergy. Antihistamines work by opposing the actions of histamine, by stopping histamine binding to its target sites in the body.

The chemical structure of non-drowsy antihistamines makes them less likely to enter the brain through what is known as the blood-brain barrier. This makes them less likely to cause drowsiness compared to other antihistamines.

Who should avoid cetirizine?

Do not take cetirizine if you have previously had an allergic reaction to cetirizine or another ingredient listed in the medication, or have reacted to an antihistamine in the past. Children under 2 years old should not take cetirizine unless prescribed by a doctor and age restrictions can vary between different cetirizine products.

Speak with your doctor or pharmacist before taking cetirizine if you are pregnant or breastfeeding, or have any of the following conditions: liver or kidney problems, epilepsy or seizures, or difficulty passing urine. You should avoid it if you are due an allergy skin test.

Cetirizine can interact with other medicines such as betahistine, certain antidepressants (called monoamine oxidase inhibitors) and dalteparin. If you take any prescription, over-the-counter or herbal medicines, ask your doctor or pharmacist to check they are safe to take alongside cetirizine.

Are there any side effects?

Common side effects can include headache, dizziness, drowsiness, restlessness, dry mouth, sore throat, diarrhoea, stomach ache and feeling sick.

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Dr Roger Henderson
Reviewed by Dr Roger Henderson
Reviewed on 13.10.2023