This NHS content is written for people in England. Medicine names, availability, prescribing and services may differ in other countries.
Common side effects of cetirizine
The most common side effect of cetirizine is feeling sleepy and tired. This happens in more than 1 in 10 people.
Other common side effects of cetirizine happen in more than 1 in 100 people. There are things you can do to help cope with them:
Feeling sleepy or tired
Try a different non-drowsy antihistamine.
Headaches
Make sure you rest and drink plenty of fluids. It's best not to drink too much alcohol. Ask your pharmacist to recommend a painkiller for your headaches.
Talk to your doctor if your headaches do not go away or are severe.
Dry mouth
Chew sugar-free gum or suck sugar-free sweets.
Feeling sick (nausea)
Try taking your tablets with food. It may also help if you stick to simple meals and avoid rich or spicy food.
Feeling dizzy
If cetirizine makes you feel dizzy when you stand up, try getting up very slowly or stay sitting down until you feel better. If you begin to feel dizzy, lie down so that you do not faint, then sit until you feel better.
Do not drive, cycle or use tools or machines if you feel dizzy or a bit shaky.
Diarrhoea
Drink plenty of water or other fluids to avoid dehydration. Speak to a pharmacist if you have signs of dehydration, such as peeing less than usual or having dark, strong-smelling pee. Do not take any other medicines to treat diarrhoea without speaking to a pharmacist or doctor.
If you take the combined pill or the progestogen-only pill and you have severe, watery diarrhoea, or any diarrhoea that lasts for more than 24 hours, your contraception may not protect you from pregnancy. Check the pill packet for advice.
Sore throat
If you're 16 or over, you can try gargling with an aspirin solution (1 soluble aspirin tablet dissolved in half a glass of water) or use a pain-relieving mouthwash such as Oraldene. Children under 16 must not be given aspirin.
If your symptoms last longer than a week, ask your pharmacist or doctor for advice.
Sneezing or blocked and runny nose
Try a different non-drowsy antihistamine.
Children are more likely to get diarrhoea, sneezing or a blocked and runny nose than adults.
Speak to a doctor or pharmacist if the advice on how to cope does not help and a side effect is still bothering you or does not go away.
View the original NHS website page ↗. Refreshed 19 August 2026.
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