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 it from a pharmacy or shop, follow the instructions that come with the packet.
Dosage and how to take cetirizine
Dosage and strength
Cetirizine comes as tablets and capsules (10mg) and as a liquid medicine (labelled either 5mg/5ml or 1mg/1ml).
The usual dose for adults and children aged 12 years old and over is 10mg once a day.
Doses are usually lower for people with kidney problems.
Dose for children under 12
For children aged 6 to 11 years old, the usual dose is 5mg, twice a day. Try to leave 10 to 12 hours between doses. For example, your child could take it first thing in the morning, and before bedtime.
For children aged 2 to 5 years old, the dose is 2.5mg, twice a day.
For children aged 1 year old, their doctor will use their weight or age to work out the right dose.
How to take it
You can take cetirizine with or without food, but always take the tablets or capsules with a drink of water, milk or squash.
Swallow them whole. Do not chew them.
Cetirizine liquid may be easier for children to take than tablets. The liquid medicine will come with a plastic syringe or spoon to give the right dose. If you do not have a syringe or spoon, ask your pharmacist for one. Do not use a kitchen teaspoon as it will not measure the right amount.
How long to take it for
How long you'll take cetirizine depends on why you're taking it.
You may only need to take cetirizine for a short time or as a one-off dose when you have symptoms. For example, you may only need to take it for a day or two if you have a reaction to an insect bite, or if you've been in contact with something that's triggered your allergy, like animal hair.
Or you may need to take it regularly for longer to prevent symptoms – for example, to stop hay fever during spring and summer.
Talk to your doctor or pharmacist if you're unsure how long you need to take cetirizine for.
If you forget to take it
If you forget a dose of cetirizine, take your forgotten dose as soon as you remember, unless it's nearly time for your next dose. In this case, skip the missed dose and take your next dose at the usual time.
Do not take 2 doses 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 missed 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 often forget doses, it may help to set an alarm to remind you. You could also ask your pharmacist for advice on other ways to help you remember to take your medicine.
If you take too much
Cetirizine is generally very safe. Taking an extra dose is unlikely to harm you or your child.
Urgent advice: Contact 111 for advice now if:
- your child takes more than the recommended dose of cetirizine, even if they have no symptoms
- you take more than the recommended dose of cetirizine and you're worried or have symptoms such as a headache, feeling sleepy or a fast heartbeat
Call 111 or get help from 111 online. Call 111 if you're asking about a child under 5 years old.
If you need to go to A&E, do not drive. Ask someone to drive you or call 999 and ask for an ambulance.
Bring the cetirizine packet or leaflet inside it, any remaining medicine, and any other medicines you take.