What it does
Cetirizine is an antihistamine that helps relieve allergy symptoms.
Commonly used for: allergic rhinitis (hay fever), urticaria (hives)
Read more in plain English ↓Plain-language summary for general understanding - not medical advice. Always follow your pharmacist/doctor.
Ask about this medicine
Answers come only from this medicine's registration record, BNF monograph and interaction data - not medical advice.
Medicine sourcing is available in Kenya only. We don't sell or dispense medicines - licensed pharmacies do.
Sourcing - Kenya onlyRegistration & product details
Source: Pharmacy and Medicines Regulatory Authority · fetched 2026-04-21 17:37:38 · updated 2026-09-29 04:33:04
About this medicine
Cetirizine is an antihistamine that helps relieve allergy symptoms.
What it treats
- allergic rhinitis (hay fever)
- urticaria (hives)
How it works
It blocks the action of histamine, a substance in the body that causes allergy symptoms.
Who it's for
Cetirizine is suitable for adults and children aged 2 years and older who have allergies.
AI-assisted summary grounded in BNF data - general information only, not medical advice. Always confirm with your pharmacist or doctor.
Clinical monograph: citirizine
Cetirizine is a second-generation antihistamine used primarily to relieve allergy symptoms such as runny nose, sneezing, and itching, as well as to treat chronic urticaria (hives). It is less sedating compared to first-generation antihistamines, making it a preferred choice for patients needing allergy relief without significant drowsiness.
Indications
- Allergic rhinitis
- Seasonal allergic rhinitis
- Perennial allergic rhinitis
- Chronic idiopathic urticaria
Dosage
Children: Refer to the BNF for Children for specific dosing guidelines.
Adults: Refer to the BNF for specific dosing guidelines.
Mechanism of action
Cetirizine selectively antagonizes peripheral H1 receptors, thereby inhibiting the effects of histamine, a chemical responsible for allergic symptoms. It blocks the action of histamine at the H1 receptor site, reducing symptoms associated with allergic reactions.
Pharmacodynamics
The onset of action for cetirizine is typically within 1 hour of administration, with peak effects occurring around 2 to 3 hours post-dose. The duration of action can last up to 24 hours, allowing for once-daily dosing. Cetirizine exhibits a lower affinity for the central nervous system H1 receptors, resulting in reduced sedation compared to older antihistamines.
Pharmacokinetics
Cetirizine is well absorbed from the gastrointestinal tract, with a bioavailability of approximately 93%. It is primarily metabolized in the liver, but the extent of hepatic metabolism is low, as most of the drug is excreted unchanged in the urine. The elimination half-life is about 8 to 10 hours in adults, and renal function can significantly affect its clearance.
Contra-indications
- Hypersensitivity to cetirizine or any of the excipients
- Severe renal impairment
Adverse effects
- Drowsiness
- Dry mouth
- Dizziness
- Fatigue
- Nausea
- Headache
Interactions
- Alcohol may enhance the sedative effects
- CNS depressants may have additive effects
- Theoretical interactions with other antihistamines
Precautions
- Caution in patients with epilepsy or at risk of seizures
- Caution in patients with impaired renal function
- May impair the ability to drive or operate machinery
Pregnancy
Cetirizine should only be used during pregnancy if the benefits outweigh the risks. Limited data suggests it is not harmful, but caution is advised.
Breast-feeding
Cetirizine is excreted in breast milk. Exercise caution when administering to breastfeeding mothers.
Storage
Store at room temperature, away from light and moisture. 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.