Levocetirizine

What it is

Levocetirizine is a second-generation antihistamine that blocks the H1 histamine receptor, the pathway responsible for itching, sneezing, runny nose and hives once histamine is released from mast cells. It is used for allergic rhinitis and other allergy symptoms, including urticaria. It reaches the brain far less than older antihistamines. In India it is a Schedule H drug and in the UK the MHRA licenses it as prescription only, so in both it is dispensed by a pharmacy against a doctor's prescription.

A usual adult range, not a national label — the dose and the timing differ by country and by product.

Used for

• Allergy

Approved uses differ by country — some of these may be off-label or unapproved where you live.

What to know while taking it

It can be taken with or without food, and evening dosing is usual because any sedation then falls during sleep. Even though it is described as non-drowsy, a noticeable minority of people do feel slowed or sleepy on it, so the effect is worth testing on a quiet day before driving or operating machinery. Alcohol and other sedating medicines add to that effect. It treats symptoms rather than the underlying allergy, so symptoms return when it is stopped.

When to see a doctor

See a doctor if drowsiness is heavy enough to interfere with driving or work, or if allergy symptoms persist or worsen despite regular use. Hives with swelling of the lips, tongue or throat, or with difficulty breathing, calls for emergency services at once.

Worth knowing

• Causes drowsiness
• Care when driving