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• Click "Print this page" on the left to print the whole section
• Download a handy PILL (Patient Information Leaflet), a two-page summary of the main questions and answers from here for promethazine for sleep. This can then be printed.

There are many other Patient Information Leaflets (PILs) across the world for patients and carers. There are also official information leaflets (often called a Data Sheet, Package Insert, or Summary of Product Characteristics). They are not on our site, so we can't take any responsibility for them but you can click here for links to other sites and leaflets

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Promethazine can make you sleepy and is used as a short term treatment of insomnia (or difficulty in getting to sleep or staying asleep). It is also an antihistamine and can help allergies. Insomnia i.e. difficulty in going to sleep or staying asleep, is not an illness itself but can cause distress and make some conditions worse e.g. bipolar mania. Any causes of insomnia should, where possible, be identified and treated. The principles of 'sleep hygiene' should also be taken seriously. These principles of sleep hygiene are:

1. Avoid excessive use of caffeine, alcohol or nicotine. A hot milky (decaffeinated) drink at bedtime may help

2. Do not stay in bed for a long time if you are not asleep

3. Avoid daytime naps or long periods of inactivity

4. A warm bath or exercise a few hours before bedtime may help sleep

5. Avoid strenuous exercise or mental activity near bedtime

6. Make sure that the bed and bedroom are comfortable and avoid excess noise and temperature (ear-plugs may help if there is much noise)

7. Get up at the same time every morning, regardless of how long you slept (this makes sure that you are ready for sleep the next night)

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The usual dose of promethazine for sleep in adults is 20-50mg at bedtime.

The usual dose in children aged 2 years or older is 15-25mg at bedtime.

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To help you choose, click on the links for the main options (self-help and help from others), the main medicines, and a handy chart comparing the main medicines for:

• Insomnia - main options, main medicines and handy chart

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Promethiazine is an antihistamine, and it seems to cause sedation by blocking histamine receptors in the brain.

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If you are having promethazine to help sleep, take it at bedtime as directed on the medicine label. Take it about half an hour to an hour before you want to go to sleep. Do not take another dose if you wake up later unless told you can do.

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Tablets:

The tablets should be swallowed with at least half a glass of water whilst sitting or standing. This is to make sure that they reach the stomach and do not stick in your throat.

Liquids:

Your pharmacist should give you a medicine spoon. Use it carefully to make sure you measure the correct amount. (Ask your pharmacist for a medicine spoon if you do not have one).

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Promethazine should start to work for insomnia in about an hour after you take it  Your doctor may need to adjust the dose to suit you, if they do not work or make you too sleepy the next morning.

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This should be discussed with your doctor as people respond differently. Promethazine should be taken in as low a dose as possible for the shortest time possible. This would ideally be for no longer than about one month or so to help you get over your problems (for more information for insomnia click here). If you need to take it for longer you should discuss this regularly with your doctor. Taking promethazine only when required or every few days (e.g. alternate nights) can be a useful way to use it safely, although it is not really addictive.

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Not really. Promethazine causes drowsiness in much the same way as the older antihistamines such as chlorpheniramine (Piriton).

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If you are taking it to help sleep, then take the dose as soon as you remember. If you take it too late at night you may feel more drowsy the next morning. Obviously if you go to sleep without the dose, that's good news.  

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If you do, you will probably have no problems, other than perhaps some "rebound insomnia" (see above).

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The table below will show you some of the main side effects you might get from promethazine. The dose to help people get to sleep is fairly low so it should not cause you too many problems.

Side effect	What happens	What to do about it
FAIRLY COMMON (more than about 1 in 10 people might get these)
Hangover	You feel sleepy or sluggish the next morning.	If you feel like this for more than a week after starting promethazine, tell your doctor. Don't drive or use machinery. Discuss this with your doctor as there are some sleeping tablets that are less likely to do this.
Dizziness	You may feel faint when you stand up.	Try not to stand up too quickly. If you feel dizzy, don't drive. Discuss with your doctor when you next see him or her.
Restlessness	Being more on edge and not able to lie still.	If this does not wear off, you might need to try something else to help you sleep.
Headache	Your head is pounding and painful.	Try paracetamol. Your pharmacist will be able to advise if this is safe to take with any other medicines you may be taking.
Nightmares	Vivid dreams	These can be upsetting but not dangerous as such. If this does not wear off, you might need to try something else to help you sleep.
Tiredness	Being weary, especially the next morning	This might mean your dose is too high. Try a lower dose.
Anticholinergic effects	Blurred vision, constipation, dry mouth	Do not drive with blurred vision. This may wear off after a few hours. See your doctor about this if it does not.

Do not be worried by this list of side effects. Some people get no side effects at all and others may get some effects that are not listed in this table. Side effects tend to be worse with higher doses. Starting with a lower dose sometimes helps. If you think you might have a side effect to your medicine, you should discuss this with your doctor, nurse of pharmacist. You should also see the manufacturer's information leaflet.

^{Updated 12.11}

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It is not thought that promethazine causes any major changes in weight. If you do start to have problems with your weight, tell your doctor next time you meet as he or she can arrange for you to see a dietician for advice. Poor sleep, however, can make you feel more hungry so click here for a few tips on helping you feel less hungry.

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Hypnotics are used to help you sleep and so promethazine should make you feel drowsy or sleepy. You may however feel drowsy the next morning so you should not drive (see below) or operate machinery until you know how it affects you. You should be careful as it may affect your reaction times, even if you feel OK.

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Medicines can affect desire (libido), arousal (erection) and how easy it is to have an orgasm. Promethazine does not have any known significant effects at the dose you take to help you sleep. Unless of course you have already gone to sleep.

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You should have no problem with any foods or drinks, other than alcohol (see separate question).

^{Updated 8.11}

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Whether or not it is safe to drink alcohol with any medicine will depend on:

• How much you have to drink e.g. the amount and over how long
• What you then try to do (e.g. sleep or drive)
• If you have any other conditions e.g. asthma or a chest infection (as alcohol can make it harder to breathe), epilepsy
• If you are taking any other medicines

Alcohol reaches all parts of the brain and can affect many things e.g. thinking, reactions and breathing. Alcohol can also boost the effect of GABA (the brain's main calming chemical messenger).

You should avoid alcohol while taking promethazine as it may make you feel more sleepy. This is particularly important if you need to drive or operate machinery and you must seek advice on this. If you take alcohol the next day e.g. lunchtime this can also make you feel more drowsy than you would expect.   

It is not safe to drive after drinking alcohol, with or without promethazine. Some countries allow driving after a small amount of alcohol but others have a zero tolerance. The UK has the highest limit in Europe, France lower, Scandanavia even lower and zero in some Eastern European countries. It is not possible to say what blood level you might have from a drink so it is safest not to drink if you know you may have to drive. It is taken as a very serious offence in most countries. You should see National Guidelines, laws and regulations in the country in which you are driving.

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You also get more drowsiness if you also take other sleeping drugs and some antidepressants and other antihistamines (for hay fever) by increasing their sedative effects.

This does not necessarily mean that this will happen in everyone or that some of these medicines can not be used together. It is just that you may need to follow your doctor's instructions very carefully. Ask your pharmacist before buying any medicine over the counter. There are many other possible drug interactions.   

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Cigarette smoke contains over 3000 different chemicals. Some of these chemicals can make some of the enzymes in the liver work faster (called "enzyme induction" of e.g. CYP1A2 or P4501A2). This means that any medicine those enzymes break down will be broken down quicker. So, you'll end up with less of that medicine if you smoke. And also you will have more of it in the body if you stop smoking. However, there seem to be no extra problems with smoking and promethazine.

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By including this section, we're not saying it's right to take illicit or illegal drugs, we're just answering the questions. With illicit drugs, the full answer is usually that we don't really know. So we can only go on a few studies, a few reports and what we know about the drugs themselves.

Cannabis (illegal in most countries):

Smoking cannabis increases the amount to dopamine in the pleasure centres of the brain, which is where the reward or buzz comes from. However, psychosis also comes from having too much dopamine in another area of the brain. You have to remember that cannabis can increase dopamine in all areas of the brain and so can make psychosis worse. Please be careful, everything in moderation and if dope makes you worse, keep off the grass. It really won't help you in the long-term. Don't forget that if you're a toker, you're also a smoker, so see the question above. However, there seem to be no extra problems with cannabis and promethazine.

Cocaine (illegal in most countries)

Cocaine is of course highly addictive and has many adverse or side effects on the body and brain. It can make most mental health symptoms worse in the long-term. However, there seem to be no extra problems with cocaine and promethazine.

Ecstasy (illegal in most countries)

Ecstasy has many effects on the brain, the main ones producing the high seem to be by boosting serotonin, noradrenaline and dopamine in the brain. While it can cause a high, the effect wears off fairly quickly. It seems that the toxic effects of the brain are cumulative i.e. the more tablets you have over your lifetime, the more chance you have of having damage to the brain e.g. long-term depression and poor memory. However, there seem to be no extra problems with ecstasy and promethazine.

Opiates

The opiates include many chemicals, some of which are used in medical care (e.g. codeine for diarrhoea and stopping coughs, diamorphine and morphine for pain). However, there seem to be no extra problems with opiates and promethazine.

^{Updated 1.12}

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You should have no problems with "The Pill" and promethazine.

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In the UK, Levonelle one step® is available and is usually known as 'the morning after pill'. It is taken to reduce the chances of becoming pregnant after unprotected sex or failure of a contraceptive method. In fact "Emergency Contraception" is the better term because it can be taken up to 72 hours (3 days) afterwards. It can be bought over-the-counter without a prescription from pharmacies. EllaOne® tablets (which may work up to 5 days afterwards) and a coil (Intra-uterine device) can also be used but must be prescribed by a Doctor.

If you are taking promethazine, the usual dose should work if you follow the instructions carefully.

N.B. We accept that for religious, cultural or ethical reasons some people do not approve of, or agree with, the use of the "Morning After" pill. However, we have answered the question because it is one of the most often asked of NHS Direct in UK, and they suggested we include it.

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Several female functions such as menstrual cycle (e.g. your periods) are controlled by a hormone called prolactin. Prolactin in the body rises during and after pregnancy and this triggers the body to make breast milk. The amount of prolactin in the body is kept in control by one part of the brain (the tuberoinfundibular system if you want to know). This area of the brain uses dopamine as its chemical messenger. Some medicines (especially antipsychotics) block the effect of dopamine in the brain. This is just what we want to help reduce some of the symptoms caused by too much dopamine e.g. psychosis, paranoia. However, if these medicines also block dopamine in the area of the brain that keeps prolactin under control, prolactin can get out of control and increase. Higher than usual levels of prolactin in the brain and blood will stop your periods (or at least make them irregular or unpredictable). Much higher levels can lead to your breasts leaking milk or lactating (the medical term is galactorrhoea). The name of the hormone (prolactin) might help you guess this anyway i.e. pro- (meaning for) -lactin (as in lactation).  High prolactin can make it more difficult to become pregnant, and over many years can have an effect on your sex-life, and maybe even your bones.

Promethazine doesn't usually have any effect on dopamine in this part of the brain and so should not have any effects on your periods. However, this can happen rarely e.g. if you are on a high dose or are sensitive to promethazine. So, if your periods are irregular or late, or you start leaking milk, then you should see your doctor about this to find if there are any other causes. If promethazine seems to be the cause, the usual thing to do is switch to another similar medicine. Reducing the dose doesn't usually work.

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It is important to consider that there will be a risk to you and your child from taking a medicine during pregnancy but also a possible risk from stopping the medicine e.g. getting ill again. Unfortunately, no decision is risk-free. It will be for you to decide which is the least risk. All we can do here is to help you understand some of the issues, so you can make an informed decision. For your information, major malformations occur "spontaneously" in about 2-4% of all pregnancies, even if no drugs are taken. The main problem with medicines is termed "teratogenicity" i.e. a medicine causing a malformation in the unborn child. A medicine causing teratogenicity is called a "teratogen". Since a baby has completed it's main development between days 17 and 60 of the pregnancy (the so-called "first trimester") these first 2-16 weeks are the main concern. After that, there may be other problems e.g. some medicines may cause slower growth. The infant may also be affected after birth e.g. withdrawal effects are possible with some drugs.

If possible, the best option is to plan in advance. If you think you could become pregnant, discuss this with your doctor and it may be possible to switch to medicines thought to carry least risk, and take other risk-reducing steps e.g. adjusting doses, taking vitamin supplements etc. If you have just discovered you are pregnant, don't panic, but seek advice from your GP within the next few days if possible. He or she may also want to refer you on to someone with more specialist knowledge of your medicine.

Very few medicines have been shown to be completely safe in pregnancy and so no manufacturer or advisor can ever say any medicine is safe. They will usually advise not to take a medicine during pregnancy, unless the benefit is much greater than the risk. In the UK, there is the NTIS (National Teratology Information Service) who offer individual risk assessments. However, their advice should always be used to help you and your doctor decide what is the risk to you and your baby. There is a risk from taking the medicine and a risk should you stop a medicine e.g. you might become ill again and need to go back on the medication again. The advice offered here is just that i.e. advice, but may give you some idea about the possible risks and what (at the time of writing) is known through the medical press.

It may be helpful to know that in the USA, the FDA (Food and Drug Administration) classifies medicines in pregnancy in five groups:
A = Studies show no risk, so harm to the unborn child appears only a remote possibility
B = Animal and human studies indicate a lack of risk but are not fully conclusive
C = Animal studies indicate a risk but there is no safety data in humans
D = a definite risk exists but the benefit may outweigh the risk in some people
X = the risk outweighs any possible benefit

Promethazine is classified as "C", and is often used in many countries to help nausea in pregnancy. However, there are some reports of problems so you should seek personal advice from your GP, who may then if necessary seek further specialist advice.

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Almost every medicine passes into breast-milk. The main questions are how much and if this is likely to have an effect on your baby. But also remember that being ill (e.g. depressed, manic, psychotic) may have more harmful and lasting effects on you and your child (such as bonding and behaviour e.g. Field, 2010) than a small amount of an effective medicine. If you have been taking a medicine while you are pregnant, you should usually be able to carry on as the amount in breast-milk is much less than the baby would have got while you were pregnant. It is usually thought to be fairly safe if the baby gets less than 10% of the mum's dose. But there may be times when although a medicine gets into breast milk the benefit may be worth the risk, so you should seek personal advice on this.

If you stop any medicine suddenly, some people can get discontinuation or withdrawal symptoms (see question above). If you have been taking a medicine during pregnancy, the same can sometimes happen to the baby when born. If the drug gets into breast milk, this can reduce the effect of suddenly not having the medicine (as well as coping with being in the big wide world too).

If you want to breast-feed there are some things you can do to reduce any risk:

• Nearly all medicines can be taken once a day. So, taking your daily dose just before the baby's longest sleep (often this will be at night) will reduce the amount the baby gets from the milk.

• Any side effects in the baby will be higher if the mum is taking a higher dose. So, try to take the lowest dose possible to still get an effect.

• Try not to take any medicines you don't really need. This includes any medicines you might buy over-the-counter

• Make sure your nurse, health visitor or doctor checks your baby for any side effects e.g. being extra sleepy, having colic, feeding problems, being floppy or poor weight gain. If there are any problems you might need to switch medicines or drop your dose a bit

• Hind milk (the second half of the feed) is likely to contain slightly more of any medicine than the first half

• Avoid new medicines if possible as there is less information about them and breast-feeding.

You must be extra careful of any medicines if your baby was pre-mature, or has kidney, liver, heart or brain problems.

We don't really know about promethazine but it seems that only a very small amount gets into the milk. You should make sure the baby is looked after carefully and checked up on by your doctor, nurse or health visitor if you decide to breast-feed with promethazine e.g. look out for the baby getting extra-sleepy, irritated or excited.

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Promethazine can reduce your ability to carry out skilled tasks such as driving or operating machinery. You may also feel drowsy the day after you take it, especially if you then drink alcohol. Until these effects wear off or you know how promethazine affects you do not drive or operate machinery. You should be careful as it may affect your reaction times, even though you may feel OK.

If you are taking any medicines, the rules about driving will depend on the country you’re driving in. Click on the links below for advice:

• Medicines and driving in the UK (England, Scotland, Northern Ireland and Wales)

• Medicines and driving in the Republic of Ireland

General advice on driving safely

If you want to drive, you should take sensible steps to reduce any risk. These could include:

• Avoid driving when you are tired or ill
• Do not drive after having any alcohol as this can make any drowsiness worse (a third of all fatal road traffic incidents involve alcohol-dependent drivers)
• Avoid driving at night, dusk or in bad weather
• Avoid motorways, dual carriageways and the rush hour
• Give yourself plenty of time. Don’t rush
• Be extra careful if you have not slept well the previous night

As some medicines can affect your driving, be extra careful:

• If starting a new medicine
• After a change in dose (especially an increase)
• If you are on a high dose or seem very sensitive to side effects
• If you are taking any medicines for other symptoms e.g. antihistamines for hay fever or allergies
• If your medicine causes you blurred vision, drowsiness, poor co-ordination, poor attention

If you are driving less than 2000 miles a year, once you consider insurance, tax, MoT, repairs, maintenance, parking and petrol, you may actually find it is cheaper to get taxis and busses, and walk the short journeys.

^{Updated 11.11}

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You should not need to have a blood test to check on your promethazine.

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