Cetirizine
Also known as: Piriteze, Zirtek, Benadryl Allergy
What it's for
Cetirizine is an antihistamine for hay fever, allergies, and hives. It blocks histamine to reduce itching, sneezing, and runny nose. It causes less drowsiness than older antihistamines.
Comes as: Tablets or liquid
How to take it
- Adults: Usually 10mg once a day.
- Take at the same time each day.
- You can take it with or without food.
- Can be taken regularly during allergy season.
Doses here are typical. Always follow the instructions from your prescriber or on the packet — they come first.
Common side effects
- Drowsiness (less common than older antihistamines)
- Headache
- Dry mouth
- Feeling sick
The leaflet inside the packet lists all known side effects.
Important safety points
- May still cause drowsiness in some people
- Take care when driving until you know how it affects you
- Avoid alcohol as it increases drowsiness
- Tell your doctor if you have kidney problems
Get medical help urgently if…
- You have signs of severe allergic reaction (anaphylaxis)
- You have severe drowsiness or confusion
- You have difficulty passing urine
- You have fast or irregular heartbeat
Call NHS 111 for urgent advice, or 999 if someone is seriously unwell.
Before you act on anything here
This page is general information, written to help you understand — it is not personal medical advice and it cannot tell you what is right for you. Talk to your own GP, pharmacist or nurse about your own health.
- Need help now but it's not an emergency? Call NHS 111 or use 111.nhs.uk.
- Emergency? Call 999 or go to A&E.