Promethazine can be taken by most adults.
Who can and cannot take promethazine Children under 6 should not be given cough and cold medicines containing promethazine if they have been bought at a pharmacy. These medicines should only be given if prescribed by a doctor.
Some types of promethazine medicines are not suitable for children over 6. Some are labelled 12+ and some are labelled 16+. Your doctor or pharmacist will advise which are the safest for children.
Promethazine is not suitable for some adults. To make sure it’s safe for you, tell your doctor or pharmacist if you:
- have ever had an allergic reaction to promethazine or any other medicine
- have an eye problem called primary angle closure glaucoma
- have problems peeing or emptying your bladder
- have epilepsy or any other health problem that causes seizures or fits
- are due to have an allergy test. Promethazine can affect your results, so you may need to stop taking it a few days before your test. Ask the clinic where you are due to have your allergy test
- are unable to have any alcohol – some liquid promethazine products contain a very small amount of alcohol, so check the ingredients and the packaging carefully
- are trying to get pregnant. Promethazine can affect home pregnancy tests. If you think you’re pregnant, speak to your doctor so they can arrange a blood test instead
4. How and when to take promethazine
If you or your child have been prescribed promethazine, follow your doctor’s instructions about how and when to take it.
Only take promethazine when you need it – for example, if you’re unable to sleep because you’re worrying about something or your cold symptoms are keeping you awake.
If you have bought promethazine or any medicine containing promethazine from a pharmacy, follow the instructions that come with it, or ask a pharmacist for advice.
Dosage and strength
Promethazine comes in 10mg, 20mg and 25mg tablets. Your dose depends on why you’re taking it:
- short-term insomnia – you’ll usually take 20mg to 50mg at night
- hay fever – you’ll usually take from 10mg twice a day to 20mg, 3 times a day
- hives – you’ll usually take from 10mg twice a day to 20mg 3 times a day
- preventing motion sickness – you’ll usually take 25mg 1 to 2 hours before a short journey or 25mg the night before a long journey
- treating motion sickness – take 25mg as soon as possible and 25mg the same evening, followed by 25mg the following evening (if you need it)
- vertigo – the dose can vary from 25mg a day to 25mg 4 times a day
If you’re taking liquid which contains 5mg of promethazine in 5ml, follow the instructions that come with the medicine for how much to take.
Doses are lower for children. Your doctor will use your child’s age to work out the right dose.
Promethazine mixed with other medicines
Promethazine can come mixed with other medicines, such as paracetamol. This is usually used to treat cough and cold symptoms. Your dose will depend on the type of medicine you’re taking.
Check the instructions on the packaging carefully, or ask your pharmacist or doctor if you’re unsure.