Hay fever and other allergic rhinitis, itchy or watery eyes, hives (urticaria), itching from allergic skin reactions, and insect bite reactions.

In an allergic reaction the body releases histamine, which makes small blood vessels leak and nerve endings itch. Cetirizine sits on the H1 histamine receptors and blocks histamine from reaching them, so the sneezing, itching, watering and swelling do not start.

Drowsiness, dry mouth, headache, tiredness and, in children, sometimes stomach pain. Drowsiness is more likely at higher doses.

Do not drink alcohol with cetirizine, and see how it affects you before driving or operating machinery. Tell your doctor about kidney disease or epilepsy, and about pregnancy or breastfeeding. Do not take other antihistamines at the same time without advice. Cetirizine is available without a prescription in Pakistan, but a persistent rash or breathing trouble needs a doctor.