Like all medicines, cetirizine can cause side effects, although not everyone gets them.
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.
Serious side effects
It's rare to have a serious side effect with cetirizine.
Call your doctor or call 111 straight away if you're bruising more easily than normal or have bleeding that takes longer to stop.
Serious allergic reaction
In rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to cetirizine.
Immediate action required: Call 999 now if:
- your lips, mouth, throat or tongue suddenly become swollen
- you're breathing very fast or struggling to breathe (you may become very wheezy or feel like you're choking or gasping for air)
- your throat feels tight or you're struggling to swallow
- your skin, tongue or lips turn blue, grey or pale (if you have black or brown skin, this may be easier to see on the palms of your hands or soles of your feet)
- you suddenly become very confused, drowsy or dizzy
- someone faints and cannot be woken up
- a child is limp, floppy or not responding like they normally do (their head may fall to the side, backwards or forwards, or they may find it difficult to lift their head or focus on your face)
You or the person who's unwell may also have a rash that's swollen, raised, itchy, blistered or peeling.
These can be signs of a serious allergic reaction and may need immediate treatment in hospital.
Do not drive yourself to A&E.
The person you speak to at 999 will give you advice about what to do.
Other side effects
These are not all the side effects of cetirizine. For a full list, see the leaflet inside your medicines packet.
Reporting side effects
You can report any suspected side effect using the Yellow Card safety scheme.
Visit the Yellow Card website for more information about reporting side effects.