Loratadine (Clarityn)

1. About loratadine

Loratadine is an antihistamine medicine that helps with the symptoms of allergies. It's used to treat:

Loratadine is known as a non-drowsy antihistamine. It's much less likely to make you feel sleepy than some other antihistamines.

Loratadine is available on prescription. You can also buy it from pharmacies and supermarkets.

It comes as tablets or as a liquid that you swallow.


3. Key facts

  • You'll usually take loratadine once a day.
  • Loratadine is classed as a non-drowsy antihistamine, but some people still find it makes them feel slightly sleepy.
  • Children may have a headache and feel tired or nervous after taking loratadine.
  • It's best not to drink alcohol while you're taking loratadine as it can make you feel sleepy.

4. Who can and cannot take loratadine

Adults and children aged 2 years and older can take loratadine.

Loratadine is not suitable for some people. To make sure it's safe for you, tell your doctor or pharmacist before taking loratadine if you:

  • have ever had an allergy to loratadine or any other medicines
  • have severe liver failure
  • have an allergy to food additives
  • have epilepsy or another illness that puts you at risk of seizures or fits
  • are due to have an allergy test – taking loratadine may affect the results, so you might need to stop taking it a few days before the test

5. How and when to take loratadine

If you or your child have been prescribed loratadine, follow your doctor's instructions about how and when to take it.

If you've bought loratadine from a pharmacy or shop, follow the instructions that come with the packet.


Loratadine comes as 10mg tablets and as a liquid medicine (labelled either 5mg/5ml or 1mg/1ml).

The usual dose in adults is 10mg once a day.

Doses are usually lower for people with liver problems.

For children, your doctor will use your child's weight or age to work out the right dose. Children aged between 6 and 12 years can only take loratadine tablets if they weigh more than 30kg. Give children loratadine liquid instead of tablets if they are under 6 or weigh 30kg or less.

How to take it

Loratadine comes as 2 different types of tablet: ordinary and melt-in-the-mouth tablets.

Swallow ordinary loratadine tablets with a drink of water, milk or juice. If the tablet has a score line across the middle, you can break it in half if you find it hard to swallow it whole. Do not chew it.

Melt-in-the-mouth tablets dissolve instantly on your tongue without needing a drink. Be careful not to crush them when you take them out of the packet.

You can take loratadine with or without food.

Loratadine liquid may be easier for children to take than tablets. The medicine will come with a plastic syringe or spoon to help you measure out 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.

When to take it

You may only need to take loratadine on a day when you have symptoms, for instance if you've been exposed to a trigger such as animal hair. Or you may need to take it regularly to prevent symptoms, such as hay fever during spring and summer.

Try to take loratadine at about the same time every day. Choose a time that is easy to remember.

What if I forget to take it?

If you forget to take a dose, take it 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 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.

What if I take too much?

Loratadine is generally very safe. If you or your child take too much, it is unlikely to harm you.

6. Side effects

Like all medicines, loratadine can cause side effects, although not everyone gets them.

Common side effects

The most common side effect of loratadine is feeling sleepy. This happens in more than 1 in 100 people.

Side effects in children may include:

  • headaches
  • feeling tired or nervous

Serious allergic reaction

In rare cases, loratadine may cause a serious allergic reaction (anaphylaxis).

These are not all the side effects of loratadine. For a full list see the leaflet inside your medicines packet.


8. How to cope with side effects of loratadine

What to do about:

  • feeling sleepy – try a different non-drowsy antihistamine. If this does not help, talk to your doctor.
  • headaches – make sure you rest and drink plenty of fluids. Ask your pharmacist to recommend a painkiller. Headaches should normally go away after the first week of taking loratadine. Talk to your doctor if they last longer than a week or are severe.
  • feeling tired or nervous – talk to your doctor or pharmacist if these side effects do not go away. They may be able to offer you a different antihistamine.

9. Pregnancy and breastfeeding

Loratadine can be taken in pregnancy. There is no good evidence that it can harm your baby.

Loratadine and breastfeeding

If your doctor or health visitor says your baby is healthy, you can take loratadine while breastfeeding.

There is some information available which shows that only tiny amounts get into breast milk. It has been used for many years in breastfeeding women without side effects in their babies.

If your baby is not feeding as well as usual, or seems unusually sleepy, or if you have any other concerns about your baby, talk to your doctor, pharmacist, health visitor or midwife.


Find out more about how loratadine can affect you and your baby during pregnancy on the Best Use of Medicines in Pregnancy (BUMPS) website.

11. Cautions with other medicines

Some medicines affect how loratadine works or can increase the chances of you having side effects.

Tell your doctor if you're taking:

  • amiodarone, a medicine used to treat an irregular heartbeat
  • cimetidine, an indigestion medicine
  • erythromycin, an antibiotic
  • ketoconazole, a medicine to treat fungal infections
  • any medicine that makes you feel sleepy, gives you a dry mouth or makes it difficult for you to pee – taking loratadine might make these side effects worse

Mixing loratadine with herbal remedies and supplements

There's very little information about taking herbal remedies and supplements with loratadine. But there might be a problem with some of them, especially ones that cause sleepiness or a dry mouth, or make it difficult to pee.

Ask your pharmacist for advice.

12. Common questions about loratadine

Page last reviewed: 14/10/2021
Next review due: 14/10/2024