How does cetirizine work?
Cetirizine is a type of medicine called an antihistamine. When you come into contact with something you're allergic to, such as pollen, animal hair or fur, your body produces a chemical called histamine.
Usually histamine is a useful substance, but in an allergic reaction it causes unpleasant symptoms including itchy, watery eyes, a running or blocked nose, sneezing and skin rashes.
Cetirizine blocks the effects of histamine and reduces these symptoms.
When will I feel better?
You should start to feel better within an hour after taking cetirizine.
Are there any long-term side effects?
Cetirizine is unlikely to do you any harm if you take it for a long time.
However it's best to take it only for as long as you need to. If you take it regularly over a long period there's a very small chance of severe itching if you stop treatment suddenly.
If you've been taking cetirizine every day for a long time, talk to your doctor before stopping it.
How does cetirizine compare with other antihistamines?
Cetirizine is known as a non-drowsy antihistamine. That's because it's less likely to make you feel sleepy than sedating antihistamines, such as chlorphenamine (Piriton).
Most people prefer to take a non-drowsy antihistamine instead of one that makes them drowsy. Sometimes, however, you may want the medicine to make you sleepy – for example, if you have itchy skin that's keeping you awake.
Other non-drowsy antihistamines, such as loratadine, desloratadine, fexofenadine and levocetirizine, seem to work just as well as cetirizine.
But cetirizine seems to be more likely to make you feel sleepy than loratadine, desloratadine or fexofenadine.
Can I take it with painkillers?
Yes, you can take paracetamol or ibuprofen while you're taking cetirizine.
Can I take 2 types of antihistamine in 1 day?
Sometimes doctors recommend that people with a severe, itchy skin rash take 2 different antihistamines together for a few days.
As well as taking a non-drowsy antihistamine during the day (such as cetirizine or loratadine), your doctor may advise that you take a drowsy antihistamine at night time if the itching is making it difficult to sleep.
Do not take 2 antihistamines together unless recommended by your doctor.
Can I take cetirizine with other hay fever treatments?
Yes, it's fine to take cetirizine alongside some other hay fever treatments – for example, you can use steroid nasal sprays (such as beclometasone (Beconase), Rhinocort Aqua and Flixonase Nasules) or eye drops, if you're taking cetirizine.
Can I take cetirizine at higher doses than on the packet?
Your doctor may prescribe a higher dose of cetirizine (up to 4 times the usual dose) for you or your child, for a severe, itchy skin rash or swelling under the skin (angioedema).
Taking high doses of cetirizine is not suitable for everyone though. Speak to your doctor if you think cetirizine is not working for you.
Will it affect my contraception?
Cetirizine does not affect any type of contraception, including the combined pill, progestogen-only pill and emergency contraception.
However, if cetirizine makes you have severe, watery diarrhoea, or any diarrhoea that lasts more than 24 hours, your contraceptive pills may not protect you from pregnancy. Check the pill packet to find out what to do.
Find out more:
Can I drive or ride a bike?
Cetirizine is classed as a non-drowsy antihistamine, but it's still possible to feel sleepy after taking it.
If this happens to you, do not drive a car, ride a bike, or use tools or machinery until you do not feel tired anymore.
It's an offence to drive a car if your ability to drive safely is affected. It's your responsibility to decide if it's safe to drive. If you're in any doubt, do not drive.
Talk to your doctor or pharmacist if you're unsure whether it's safe for you to drive while taking cetirizine. GOV.UK has more information on the law on drugs and driving.
Can I drink alcohol while taking cetirizine?
It's best not to drink alcohol while you're taking cetirizine as it can make you feel sleepy.
Is there any food or drink I need to avoid?
You can eat and drink normally while taking cetirizine.
Can lifestyle changes help with hay fever?
If you have hay fever, it will help if you do not spend too much time outside when the pollen count is high.
Tips for when you're outside
- Do not cut grass or walk on grass.
- Wear wraparound sunglasses to stop pollen getting into your eyes.
- Put Vaseline around your nostrils to help trap pollen.
- Shower and change your clothes after you've been outside to wash off pollen.
Tips for when you're inside
- Keep windows and doors shut as much as possible.
- Vacuum regularly and dust with a damp cloth.
- Do not keep fresh flowers in the house.
- Do not smoke or be around smoke as it makes hay fever symptoms worse.