Cetirizine

What is Cetirizine used for?

Cetirizine is a second-generation antihistamine that selectively blocks H1 receptors to relieve allergy symptoms such as sneezing, runny nose, itchy eyes/skin and hives. Compared with first-generation antihistamines, it crosses the blood-brain barrier less, so it is less likely to cause drowsiness, and its effect lasts longer, typically requiring only once-daily dosing.

How to take Cetirizine and adjust the dose

Adults and children over 12: 10mg once daily. Children 6–12 years: 10mg once daily or 5mg twice daily; children under 30kg are generally advised 5mg daily. Children 2–6 years: typically 2.5mg twice daily. Infants under 2 should consult a pediatrician. Elderly patients generally do not need dose adjustment, but those with poor kidney function require dose/interval adjustment by a doctor. May be taken with or without food.

Cetirizine side effects

• Common: drowsiness, fatigue, dry mouth, headache, abdominal pain
• Serious (rare): severe allergic reaction (hives, swelling, difficulty breathing)

Who should not take Cetirizine?

• Allergy to cetirizine, hydroxyzine, or piperazine derivatives
• Severe renal impairment (creatinine clearance below 10 mL/min)
• Not for self-use in children under 2 without medical guidance
• Use with caution in those with seizure disorders or prone to urinary retention
• Avoid alcohol while taking this medicine