Cetirizine is an antihistamine medicine that relieves the symptoms of allergies. It’s used to treat hay fever, allergic conjunctivitis (red, itchy eye), eczema and hives. It’s also used for reactions to insect bites and stings and for some food allergies.
Cetirizine is known as a non-drowsy antihistamine. It's much less likely to make you feel sleepy than some other antihistamines.
Cetirizine is available on prescription. You can also buy it from pharmacies and supermarkets.
It comes as tablets, capsules and as a liquid that you swallow.
- It's usual to take cetirizine once a day. Children sometimes take it twice a day.
- Cetirizine is classed as a non-drowsy antihistamine, but some people still find it makes them feel quite sleepy.
- Common side effects include headache, dry mouth, feeling sick, dizziness, tummy pain and diarrhoea.
- It’s best not to drink alcohol while you’re taking cetirizine as it can make you feel sleepy.
- Cetirizine is also called by the brand names Benadryl Allergy, Piriteze and Zirtek.
Who can and can't take cetirizine
Cetirizine tablets and liquid that you buy from pharmacies and supermarkets can be taken by adults and children aged 6 and older.
Children over the age of 2 can also take liquid cetirizine for hay fever and skin allergies.
Cetirizine can also be taken under medical supervision by children aged 1 year and older.
Cetirizine isn't suitable for some people. Tell your doctor or pharmacist if you:
- have had an allergic reaction to cetirizine or any other medicines in the past
- have an allergy to peanuts or soya
- have an allergy to the food additives, E218 or E216
- have an intolerance to, or cannot absorb, some sugars such as lactose or sorbitol
- have liver or kidney failure
- have epilepsy or another health problem that puts you at risk of fits
- have an illness that means you're more likely to retain pee
- have a rare illness called porphyria
- are booked to have an allergy test – taking cetirizine may affect the results, so you might need to stop taking it a few days before the test
How and when to take
If you or your child have been prescribed cetirizine, follow your doctor's instructions about how and when to take it. If you've bought cetirizine from a pharmacy or shop, follow the instructions that come with the packet.
How much should I take?
Cetirizine comes as tablets and capsules (10mg) and as a liquid medicine (labelled either 5mg/ml or 1mg/1ml).
The usual dose in adults is 10mg once daily.
Doses are usually lower for people with kidney problems.
For children, your doctor will use your child's weight or age to work out the right dose. If you've bought cetirizine for a child, follow the instructions on the packet.
Depending on their age, children may take cetirizine twice a day. In this case, try to space the doses 10 to 12 hours apart.
How to take it
You can take cetirizine with or without food.
Always take cetirizine tablets or capsules with a drink of water, milk or juice. Swallow them whole. Do not chew them.
Cetirizine liquid may be easier for children to take than tablets or capsules. The liquid medicine will come with a plastic syringe or spoon to help you measure out the right dose. If you don't have a syringe or spoon, ask your pharmacist for one. Do not use a kitchen teaspoon as it will not give the right amount.
When to take it
You may only need to take cetirizine on a day you have symptoms, such as if you’ve been exposed to a trigger like animal hair. Or you may need to take it regularly to prevent symptoms, such as to stop hay fever during spring and summer.
What if I forget to take it?
Take your forgotten dose as soon as you remember, unless it is nearly time for your next dose. Do not take a double dose to make up for a forgotten dose.
If you forget to give a dose to a child who is taking cetirizine twice a day, you can give the dose if it's within 4 hours of when they should have had it. If you remember more than 4 hours after, do not give the missed dose. Instead, wait until the next dose and carry on as normal.
If you forget doses often, it may help to set an alarm to remind you. You could also ask your pharmacist for advice on other ways that are suitable for you and your medicines.
What if I take too much?
Cetirizine is generally very safe. Taking too much is unlikely to harm you or your child.
If you take an extra dose by mistake, you might get some of the common side effects. If this happens or you’re concerned, contact your doctor.
Like all medicines, cetirizine can cause side effects although not everyone gets them.
Common side effects
Common side effects of cetirizine happen in more than 1 in 100 people. Talk to your doctor or pharmacist if these side effects bother you or don’t go away:
- feeling sleepy and tired
- dry mouth
- feeling sick or dizzy
- tummy pain
- sore throat
- cold-like symptoms of the nose
- itch or rash
- tingling in the hands and feet
- feeling agitated
Children are more likely to get diarrhoea or cold-like symptoms of the nose than adults.
Serious side effects
It's rare to have a serious side effect with cetirizine.
Tell your doctor straight away if you have:
- bruising or bleeding more than normal
Serious allergic reaction
In rare cases, it’s possible to have a serious allergic reaction to cetirizine.
A serious allergic reaction is an emergency. Contact a doctor straight away if you think you or someone around you is having a serious allergic reaction.
The warning signs of a serious allergic reaction are:
- getting a skin rash that may include itchy, red, swollen, blistered or peeling skin
- tightness in the chest or throat
- having trouble breathing or talking
- unusual hoarseness
- swelling of the mouth, face, lips, tongue, or throat
These are not all the side effects of cetirizine. For a full list see the leaflet inside your medicines packet.
You can report any suspected side effect to the UK safety scheme.
How to cope with side effects
What to do about:
- feeling sleepy - try a different non-drowsy antihistamine. If this doesn't help, talk to your doctor.
- feeling sick - stick to simple meals and don’t eat rich or spicy food
- headache - take an everyday painkiller like paracetamol or ibuprofen
- diarrhoea - drink plenty of water in small, frequent sips. It may also help to take oral rehydration solutions. You can buy these from a pharmacy or supermarket to prevent dehydration. Don’t take any other medicines to treat diarrhoea without speaking to a pharmacist or doctor.
Cautions with other medicines
Some medicines and cetirizine interfere with each other and increase the chances of you having side effects. Check with your pharmacist or doctor if you're taking:
- midodrine, a medicine used to treat low blood pressure
- ritonavir, a medicine used to treat HIV infection
- any medicine that makes you drowsy, gives you a dry mouth, or makes it difficult for you to pee. Taking cetirizine might make these side effects worse.
Mixing cetirizine with herbal remedies and supplements
There might be a problem taking some herbal remedies and supplements alongside cetirizine - especially ones that cause sleepiness, a dry mouth or make it difficult to pee.
Ask your pharmacist for advice.
Tell your doctor or pharmacist if you're taking any other medicines, including herbal remedies and supplements.
Pregnancy and breastfeeding
You can take cetirizine while you're pregnant. However a similar antihistamine called loratadine is normally used first because there's more information to say that it's safe.
Cetirizine isn't thought to be harmful during pregnancy, but as very few pregnant women have been studied, it is not possible to be certain.
Talk to your doctor about the benefits and possible harms of taking cetirizine. It will also depend on how many weeks pregnant you are and the reason you need to take cetirizine.
Cetirizine and breastfeeding
It's generally safe to take cetrizine if you're breastfeeding as only small amounts get into breast milk.
However, speak to your doctor before taking cetirizine if your baby was premature, had a low birth weight or has other health problems.
For safety, tell your doctor if you’re pregnant or breastfeeding.
How does cetirizine work?
When will I feel better?
How long should I take cetirizine for?
Is it safe to take cetirizine for a long time?
Can I drink alcohol with it?
Is there any food or drink I need to avoid?
Can I drive or ride a bike with it?
What's the difference between cetirizine and other antihistamines?
What's the difference between cetirizine and other non-drowsy antihistamines?
Can I take it with painkillers?
Can I take more than one antihistamine together?
Can I take cetirizine with other hay fever treatments
Can I take cetirizine at higher doses than on the packet?
Will it affect my fertility?
Will it affect my contraception?
Can lifestyle changes relieve hay fever?