What it does
Cetirizine is an antihistamine used to relieve allergy symptoms.
Commonly used for: hay fever (allergic rhinitis), hives (urticaria), allergic reactions
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Source: Food and Drugs Authority · fetched 2026-04-18 08:37:08 · updated 2026-09-15 04:00:13
About this medicine
Cetirizine is an antihistamine used to relieve allergy symptoms.
What it treats
- hay fever (allergic rhinitis)
- hives (urticaria)
- allergic reactions
How it works
Cetirizine works by blocking the effects of histamine, a substance in the body that causes allergy symptoms.
Who it's for
Cetirizine is suitable for adults and children over the age of 6 who suffer from allergies.
Cautions
- • May cause drowsiness in some people.
- • Consult a doctor if you have kidney problems.
AI-assisted summary grounded in BNF data - general information only, not medical advice. Always confirm with your pharmacist or doctor.
Clinical monograph: cetrizne
Cetirizine is a second-generation antihistamine commonly used for the relief of allergic symptoms such as rhinitis and urticaria. It is known for its ability to reduce the effects of natural histamine in the body, which is responsible for allergy symptoms. Cetirizine is less sedating compared to first-generation antihistamines, making it a preferred choice for individuals who need to avoid drowsiness.
Indications
- Allergic rhinitis
- Seasonal allergic rhinitis (hay fever)
- Perennial allergic rhinitis
- Chronic urticaria (hives)
Dosage
Children: Refer to the BNF for Children for specific pediatric dosing recommendations.
Adults: Refer to the BNF for specific dosing guidelines.
Mechanism of action
Cetirizine selectively antagonizes peripheral H1 receptors, thereby inhibiting the action of histamine, a substance that contributes to allergic symptoms. This action reduces the effects of histamine on blood vessels and tissues, alleviating symptoms such as itching, sneezing, and runny nose.
Pharmacodynamics
The onset of action for cetirizine typically occurs within one hour of administration, with peak effects observed at approximately 1 to 2 hours. The duration of action is notably long, lasting up to 24 hours, which allows for once-daily dosing. Cetirizine has been shown to improve the quality of life for patients suffering from allergic conditions by significantly reducing symptoms.
Pharmacokinetics
Cetirizine is rapidly absorbed after oral administration, with a bioavailability of approximately 93%. The drug is approximately 93% bound to plasma proteins and is primarily metabolized in the liver, although its metabolism is limited. The elimination half-life ranges from 8 to 10 hours in healthy adults, and renal impairment may necessitate dose adjustments due to decreased clearance. Cetirizine is excreted primarily in urine, with about 60% of a dose excreted as unchanged drug.
Contra-indications
- Hypersensitivity to cetirizine or any of its components
- Severe renal impairment
Adverse effects
- Drowsiness
- Dry mouth
- Dizziness
- Fatigue
- Nausea
- Headache
- Gastrointestinal disturbances
Interactions
- Alcohol may enhance the sedative effects
- CNS depressants may increase sedative effects
- Theophylline may reduce the clearance of cetirizine
Precautions
- Use with caution in patients with a history of seizures
- Caution in patients with impaired liver function
- Avoid driving or operating machinery until the individual response to cetirizine is known
Pregnancy
Cetirizine should be used during pregnancy only if clearly needed, as safety has not been established.
Breast-feeding
Cetirizine is excreted in breast milk, caution is advised when administered to nursing mothers.
Storage
Store at room temperature, away from moisture and heat. Keep out of reach of children.
Formulations
- Tablets
- Oral solution
- Chewable tablets
AI-synthesized from BNF references - general information only, not a substitute for professional medical advice or the current BNF. Verify doses with a pharmacist.