Chlorphenamine (Piriton)

1. About chlorphenamine

Chlorphenamine is an antihistamine medicine that relieves the symptoms of allergies.

It's known as a drowsy (sedating) antihistamine. This means that it is likely to make you feel more sleepy than some other antihistamines.

It's used for:

Chlorphenamine is available on prescription, and to buy from pharmacies.

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

Chlorphenamine is sometimes mixed with other medicines like ephedrine or pseudoephedrine to treat coughs and colds.

When chlorphenamine is mixed with other medicines, it can be called Galpseud Plus Linctus and Haymine.


3. Key facts

  • Chlorphenamine usually takes 30 minutes to 1 hour to work.
  • Common side effects include feeling sick (nausea), sleepy or dizzy. You may also have difficulty concentrating, a dry mouth, headaches or blurred vision.
  • Wait a minimum of 4 hours between taking doses.
  • Do not drink alcohol while you're taking chlorphenamine. Alcohol may make you feel sick or more sleepy.
  • If you've bought chlorphenamine from a pharmacy without a prescription, do not take it for longer than 2 weeks. If you are still having symptoms, speak to your doctor.

4. Who can and cannot take chlorphenamine

Chlorphenamine can be taken by most adults.

Children and chlorphenamine

You can buy cough, cold and other medicines that contain chlorphenamine from pharmacies. This type of chlorphenamine should not be given to children under the age of 6.

Children under 6 should only be given chlorphenamine that has been prescribed by their doctor.

Who may not be able to take chlorphenamine

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

  • have ever had an allergy to chlorphenamine or any other medicine
  • have an eye problem called primary angle closure glaucoma
  • have problems peeing or emptying your bladder
  • have epilepsy or another health problem that puts you at risk of fits or seizures
  • are due to have an allergy test – taking chlorphenamine may affect the results, so you might need to stop taking it a few days before the test. Ask a pharmacist or your doctor for advice
  • are unable to have any alcohol – some liquid chlorphenamine products contain a very small amount of alcohol. Check the ingredients and the packaging carefully
  • are a frail, older adult – you may experience more side effects, such as confusion

5. How and when to take chlorphenamine

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

If you have bought chlorphenamine or any medicine containing chlorphenamine from a pharmacy, follow the instructions that come with the packet, or ask your pharmacist for advice.

If you or your child's symptoms do not get better within a few days, talk to a doctor.

Dosage and strength

Chlorphenamine comes as 4mg tablets and the liquid comes as 2mg in 5ml.

If you're taking liquid chlorphenamine, follow the instructions that come with the medicine for how much to take.

The usual dose is:

  • adults and children aged 12 years and older – 1 tablet every 4 to 6 hours. Do not take more than 6 tablets in 24 hours
  • children aged under 12 years – doses are lower for children and babies, and they may take it less often than an adult. Your doctor will use your child's age to work out the right dose. Children should only take chlorphenamine that has been prescribed by a doctor. Do not give children under 6 years cough or cold medicines that contain chlorphenamine
  • older adults who are frail – 1 tablet every 6 to 8 hours. Do not take more than 3 tablets in 24 hours. Speak to your doctor or pharmacist before taking it as you're more likely to get side effects

When used for coughs and colds, chlorphenamine is mixed with other medicines in a liquid that you swallow. Follow the instructions on the bottle or packaging for how much to take.

How to take chlorphenamine

You can take chlorphenamine with or without food.

Swallow chlorphenamine tablets with a drink of water, milk or juice. The 4mg tablets can be broken in half for children and people taking lower doses.

Chlorphenamine 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 because it will not measure the right amount.

When to take it

Only take chlorphenamine when you need to.

For allergies, you may only need to take chlorphenamine on the days you feel you need to. For example, coming into contact with something like animal hair may have triggered your symptoms.

For hay fever, you may need to take it regularly to prevent symptoms during spring and summer.

If you forget to take it

Take your forgotten dose as soon as you remember, unless it's nearly time for your next dose.

Do not take 2 doses at the same time, or take an extra dose to make up for a forgotten one.

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 to help you remember to take your medicine.

If you take too much

If you have taken more than the recommended dose of chlorphenamine, you may:

  • feel very sleepy
  • feel nervous or restless
  • feel or be sick (nausea or vomiting)
  • get blurred vision
  • get a very fast, uneven or pounding heartbeat (palpitations)

In serious cases, you can have a fit or seizure, or become unconscious, and may need emergency treatment in hospital.

If you need to go to A&E, do not drive yourself. Get someone else to drive you or call for an ambulance.

Take the chlorphenamine packet or leaflet inside it, plus any remaining medicine, with you.

6. Side effects

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

Common side effects

Common side effects of chlorphenamine happen in more than 1 in 100 people.

Talk to your doctor or pharmacist if these side effects bother you or do not go away:

  • feeling sleepy during the daytime
  • feeling sick (nausea)
  • feeling dizzy or difficulty concentrating
  • dry mouth
  • headaches
  • blurred vision

Children and people aged over 65 have more chance of getting some side effects, such as feeling restless, excited or confused.

Serious side effects

Tell your doctor straight away if:

  • the whites of your eyes turn yellow, or your skin turns yellow although this may be less obvious on brown or black skin – these can be signs of liver problems
  • you are bruising or bleeding more than normal

Serious allergic reaction

In rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to chlorphenamine.

These are not all the side effects of chlorphenamine. For a full list, see the leaflet inside your medicine packet.


8. How to cope with side effects of chlorphenamine

What to do about:

  • feeling sleepy during the daytime – drowsiness usually wears off 4 to 6 hours after a dose. Do not drive, ride a bike or use tools or machinery if you're feeling this way.
  • feeling sick (nausea) – it may help if you do not eat rich or spicy food while you're taking chlorphenamine.
  • feeling dizzy or difficulty concentrating – stop what you're doing and sit or lie down until you feel better. If the feeling does not go away or is troubling you, do not take any more medicine and speak to a pharmacist or your doctor.
  • dry mouth – chew sugar-free gum or suck sugar-free sweets.
  • headaches – make sure you rest and drink plenty of fluids. Ask your pharmacist to recommend a painkiller. Talk to your doctor if the headaches last longer than a week or are severe.
  • blurred vision – do not drive, ride a bike or use tools or machinery while this is happening. This should only be a mild problem in most people who are affected but if it bothers you, speak to your pharmacist or doctor as they may need to change your treatment.

9. Pregnancy and breastfeeding

Chlorphenamine can be used in pregnancy. There is no good evidence that it is harmful to your baby, but it can have side effects such as feeling drowsy.

Your doctor or pharmacist may recommend a non-drowsy antihistamine (loratadine) before chlorphenamine.

Chlorphenamine and breastfeeding

If your doctor or health visitor says your baby is healthy, you can use chlorphenamine during breastfeeding. This is a drowsy antihistamine, so it is better to take occasional doses or only for a short time.

It is not known how much chlorphenamine gets into breast milk, but it has been used for many years without causing babies to have side effects. However, chlorphenamine can cause drowsy symptoms, so may also make your baby sleepy too.

If you're breastfeeding or planning to breastfeed, talk to your doctor or pharmacist as other medicines might be better while breastfeeding.

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


Find out more about how chlorphenamine 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 and chlorphenamine affect each other and increase the chances of you having side effects.

Check with your pharmacist or doctor if you're taking:

  • a type of antidepressant called a monoamine oxidase inhibitor, such as phenelzine
  • phenytoin (an anti-epilepsy medicine)
  • any medicine that makes you drowsy, gives you a dry mouth, or makes it difficult for you to pee – taking chlorphenamine might make these side effects worse

Mixing chlorphenamine with herbal remedies and supplements

There might be a problem taking some herbal remedies and supplements alongside chlorphenamine, especially ones that cause side effects such as sleepiness, a dry mouth or making it difficult to pee.

12. Common questions about chlorphenamine

Page last reviewed: 05/11/2021
Next review due: 05/11/2024