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Your guide to medication Chlorpromazine

Chlorpromazine is an antipsychotic medication that can be used to treat anxiety, mania, psychosis and schizophrenia.

Medication name: Chlorpromazine ("klor-PRO-ma-zeen")
Brand name: Largactil ("lar-GAK-til")
Medication type: Antipsychotic (also called a first-generation antipsychotic or a phenothiazine medicine)

Ways to take chlorpromazine
Tablets: 25mg, 50mg, and 100mg strengths
Liquids: 25mg per 5ml (one 5ml spoonful is like a 25mg tablet) and 100mg/5ml (this is a much stronger solution)
Injections: This is a short-acting injection containing 25mg in 1ml of injection. It is usually used in hospital when needed in an emergency. It is injected deep into a muscle.

What can it be used for?
The doctor can prescribe chlorpromazine as a licensed medicine for schizophrenia, autism, mania, severe anxiety, agitation and dangerous or violent impulsive behaviour for children and young people aged one or over.

Find out more about schizophrenia

About chlorpromazine

How chlorpromazine works

Chlorpromazine is a ‘first-generation antipsychotic’ (sometimes described as a ‘conventional antipsychotic’).

An antipsychotic medicine helps to adjust the levels of dopamine and other chemicals available in your brain. Chlorpromazine reduces dopamine activity where it is too high, helping with symptoms like hallucinations.

Find out more about schizophrenia

Chlorpromazine and everyday life

Frequently asked questions

It can take a few days for chlorpromazine to take effect. It’s difficult to determine how long you can expect to wait, as the medication affects each person differently.

If you have had no change after three to four days of taking chlorpromazine, talk to your doctor. Don’t increase your dose yourself if you think the medication isn’t working.

Your weight could be affected by taking chlorpromazine. It’s very difficult to know how much weight (if any) you might gain, as each person is affected differently.

Your doctor should weigh you before you start taking chlorpromazine and every week for the first three months. They should then check your weight and waist measurement at least every six months. You can also do this yourself at home and keep a chart to show your doctor.

Young people naturally gain a little weight each year as they grow, but anything more than this should be monitored.

If you put on a large amount of weight while taking this medication, there are lots of other antipsychotic medications you can try. You can also take steps to lose any excess weight through healthy eating and exercise.

Talk to your doctor if weight gain while taking this medication worries you.

People taking chlorpromazine can also get some growth of the breasts and some milk flow when taking this medication, regardless of gender.

Your skin colour can be affected by chlorpromazine if you take it for a long time, taking on a blue-grey tint. This is because it increases the amount of melanin in your skin (the pigment that makes your skin go darker when you have a tan).

Melanin can also build up in your eyes although this should not affect your eyesight.

Your skin may also burn more easily in the sun while taking this medication and you could get rashes or other skin reactions from too much UV light. For this reason, you should not use a tanning bed while taking chlorpromazine. Spray-tanning is fine and a much safer option in general.

If you are exposed to the sun, use plenty of high-factor sunscreen and cover up whenever possible.

You may want to let your family and friends know you are taking chlorpromazine so they can support you and help you look out for side effects.

For guidance on this, check out our page on getting support with your medication.

Chlorpromazine can affect your sleep in a few different ways – you may feel more tired and sleep more than normal, you may find it difficult to get to sleep, or you may experience nightmares.  

Things should settle after the first few days. If not, you should go back to your doctor and talk through your options.

Alcohol

When you first start to take this medication, combining alcohol with chlorpromazine will make you feel very sleepy, so you should avoid it altogether.

Once your body has got more used to the chlorpromazine, this effect should be reduced. It’s best to stick to drinking only small amounts of alcohol and to have a plan for getting home safely.

Street drugs

Be careful if you are also using street drugs, as antipsychotics like chlorpromazine block the effect of dopamine, meaning that the ‘high’ you are used to may not be as potent as before. This could lead you to increase the dose of the street drug to make up for it, which could be very dangerous.

Smoking

Cigarette smoke affects the amount of chlorpromazine in your body. So, if you start or stop smoking while you are taking chlorpromazine, you may have to change your dose.

If you already smoke when you begin taking this medication, you will probably need a higher dose than somebody who does not smoke. You should tell your doctor if you smoke and how much, so that he or she can prescribe the correct dose for you.

It is the smoke, rather than nicotine, that has this effect so it should not be a problem if you only vape.

Chlorpromazine does not mix well with some other medications.

Tell your doctor or pharmacist if you are taking any other kind of medication as they may need to change your dose of chlorpromazine or prescribe you a different medication.

Other medications include tablets or liquids that you buy over the counter to treat common illnesses such as colds and flu, or topical medications that are applied to the skin.

Chlorpromazine may cause problems for people with certain allergies or intolerances:

  • Chlorpromazine tablets contain lactose and may not be suitable for people who have problems eating some sugars or dairy (milk-based) products.
  • Chlorpromazine oral syrup contains sorbitol and sugars; methyl, ethyl and propyl parahydroxybenzoates (additives that can cause allergies in some people); and a small amount of alcohol (though not enough to cause a change in your blood levels).
  • Chlorpromazine sugar-free oral solution contains: sorbitol and sugars; aspartame (not suitable for people with a condition called phenylketonuria); sunset yellow E110 (an additive causing allergies in some people); and a small amount of alcohol (though not enough to cause a change in your blood levels).
  • Chlorpromazine injections contain sulphites that can cause allergies in some people.

There are many manufacturers of liquid chlorpromazine products so talk to your pharmacist if you are concerned about any of chlorpromazine’s ingredients and their potential effects.

Chlorpromazine may make you feel very tired and woozy when you start taking it, and it may affect your eyesight, so you should not ride a bike or drive a car until you become used to this medication. Arrange alternative methods of transport for a few days or weeks until you know how you will be affected.

You should also be very careful when doing anything else that requires concentration, such as operating machinery or exercising.

Don’t worry – most people are able to drive or ride a bike as normal once they are settled on chlorpromazine. 

Pregnancy

Chlorpromazine has been used in humans during pregnancy for a long time with no signs of increased risk to you or your unborn baby.

Babies do better when their mums are mentally well, so if chlorpromazine has beneficial effects on your mental health, it may be best to continue taking it throughout pregnancy. Your doctor can help you weigh up the pros and cons.

Pregnant woman are advised to take folic acid – this is safe to do while also taking chlorpromazine.

You may also be checked for increased risk of blood clots during pregnancy and may be prescribed a course of blood-thinning injections. This is standard practice and nothing to worry about.

Women taking more than 500mg a day of chlorpromazine may have a longer labour than might normally be expected. 

Post-natal

You should talk to your doctor or midwife to discuss plans for after the birth.

Chlorpromazine can cause side effects in newborn babies including withdrawal symptoms.  This could mean that your baby is either very sleepy or very excited, could shake and/or have weak or stiff muscles. Your baby may also have difficulty sleeping and breathing.

Breastfeeding

Chlorpromazine is passed to the baby in breast milk, but only in small amounts.

Talk to your midwife or doctor to discuss feeding options before your baby is born, so that you can be prepared.

Breastfeeding might be beneficial in offsetting some of the withdrawal effects in your baby.

Sex

Chlorpromazine can have side effects that might affect your sex life. These include:

  • an erection that is painful and lasts for a long time (priapism) can occur when taking chlorpromazine. If this happens, you should see your doctor straight away
  • difficulty having an orgasm (coming/climaxing), or having an orgasm without ejaculating (no sperm comes out)
  • lighter periods, or no periods at all. If you normally have periods, your doctor should monitor this while you are taking chlorpromazine

If you experience any of these symptoms, talk to your doctor.

After you have taken chlorpromazine for a few weeks, you should begin to feel the benefits of the medication which may include improvements in your relationships and, consequently, your sex life.

Fertility

You should tell your doctor if you are pregnant or trying for a baby before taking chlorpromazine.

Chlorpromazine can affect your fertility. This is because it increases the amount of the hormone prolactin in the body. Prolactin is the hormone released by breastfeeding, which may have some contraceptive effect (may make it harder to get pregnant).

Make sure you use a reliable method of contraception while you are taking chlorpromazine if you do not wish to become pregnant. If you’re not sure what method to use, visit your doctor or make an appointment at a sexual health clinic to discuss your options.

If you become pregnant while taking chlorpromazine, you should let your doctor know immediately.

Chlorpromazine is not a banned substance in sport.

It may make you feel tired and woozy, and affect your eyesight when you first start taking it, so you may wish to stop playing sports for the first few days, until you know more about how it affects you.

Don’t worry, most people can play the sports they normally enjoy while taking this medication.

Talk to your doctor before starting to take chlorpromazine if you are about to sit any exams or tests, as the medication can initially make you feel very tired and woozy, and it may affect your eyesight. You might decide together to delay starting it until you have done them, or your doctor might suggest some alternative medications.

If your exams are more than a week away, however, you may decide with your doctor that it’s better to start taking chlorpromazine to improve your motivation to study.

Try not to worry – most people take exams and tests as normal while on chlorpromazine.

Your doctor should know

  • You need to talk to your doctor or pharmacist before starting treatment with chlorpromazine if any of the following apply to you:

    • you have high blood sugar (symptoms include being thirsty all the time, needing to wee often, decrease in appetite and/or feeling weak)
    • you have ever had seizures (fits)
    • you have Parkinson’s disease
    • you have heart problems, or a family history of heart problems including strokes and heart failure
    • you have ever had blood clots, or you have a family history of blood clots
    • you have myasthenia gravis, with weak or tired muscles that can make it difficult to breathe
    • you have an underactive thyroid gland (hypothyroidism)
    • you have liver or kidney problems
    • you have glaucoma (raised pressure in the eye)
    • you have a condition called phaeochromocytoma (high blood pressure caused by a tumour near the kidney)
    • you have an enlarged prostate gland

Uses, warnings, safety and side effects

Taking chlorpromazine

How long will I need to take chlorpromazine for?

Young people usually take chlorpromazine for many months or years. Your doctor should talk to you about how long you might expect to stay on this medication.

Ideally, you should stay on an antipsychotic medication for four to six weeks before deciding whether to continue taking it in the long term. This gives the medication a chance to build up in your system and to begin delivering its full effects.

Your doctor should review your progress on this medication at least once a year.

You should only take chlorpromazine as agreed with your doctor

You will get the best effect from chlorpromazine if you take it regularly at the dose prescribed by your doctor.

Make sure that you know your dose. If it's not written on the label, check with your pharmacist or doctor.

Some people start with a low dose of chlorpromazine in liquid form before moving on to tablets as their dose increases.

At the start, you may take chlorpromazine three or four times a day, but as it’s a long-acting drug, you’ll probably be able to avoid taking it during school or college hours.

If you do have to take your medication at school or college, ask your doctor to help you talk to a teacher or school nurse about how best to do this (some people prefer to keep a separate supply of medicine at school or college, for instance - your pharmacist can help with that).

Tablets and liquid can be taken before or after food. Swallow tablets whole with a drink of water – if chewed, they taste horrible!

The liquid medicine can be mixed with your favourite cold drink or added to food, if you prefer.

It’s possible to administer a fast-acting dose of chlorpromazine by injection if you’re having serious symptoms. You must visit a doctor or nurse for this and should stay lying down for 30 minutes after receiving the injection. Your blood pressure will probably be taken during this time, to check it’s within normal levels.

What if I miss a dose?

If you forget to take a dose of chlorpromazine, carry on from the next dose.

Do not take a double dose.

What will happen if I forget to take my chlorpromazine?

If you forget to take this medication for a few days, your old symptoms might start coming back. If this happens, talk to your doctor without delay.

Stopping the use of chlorpromazine

Once you start taking an antipsychotic medication, the brain adjusts to having a new level of dopamine around. If you stop taking the antipsychotic all at once, the balance starts to change again, meaning you could get your old symptoms back.

Stopping this medicine quickly, or reducing the dose too much at once, may also give you ‘kick-back’ symptoms like feeling sick, being sick, shaking, uncontrolled movements of the hands and body, and finding it hard to get to sleep.

You can stop taking chlorpromazine safely and gradually over several days or weeks with your doctor’s help.

Warnings and safety

Safety headlines

If you have taken more chlorpromazine than the dosage recommended by the doctor who prescribed it to you, you must get medical help immediately - even if you do not feel any different.

Take along a friend or family member if possible, in case you start to feel ill on the way.

You should also take your medication with you and tell the staff there how much you have taken.

When to go to the hospital

If you have taken more chlorpromazine than the dosage recommended by the doctor who prescribed it to you, you must get medical help immediately - even if you do not feel any different.

Take along a friend or family member if possible, in case you start to feel ill on the way.

You should also take your medication with you and tell the staff there how much you have taken.

Taking too much chlorpromazine may result in:

  • quick and shallow breathing
  • low body temperature
  • low blood pressure
  • restlessness
  • twisting of your arms and legs
  • seizures (fits)
  • unusual heartbeat

If you experience any of the following symptoms, you should stop taking chlorpromazine and go to the hospital straight away:

  • difficulty in swallowing, or swelling in the mouth, tongue, face and throat
  • itching, or a rash on your body (this could be an allergic reaction)
  • muscles going stiff or rigid with high fever; sweating; looking pale; feeling strange; fainting or losing consciousness; or tachycardia (very rapid or irregular heartbeat) - this may be a serious and life-threatening side effect called neuroleptic malignant syndrome
  • a painful erection that lasts for a long time (priapism)
  • skin reactions including rashes, flaking of the skin or red blisters on the skin. Remember: you need to apply a high-protection sunscreen before you go out in fine weather as chlorpromazine makes the skin more sensitive to sunlight
  • your skin and the whites of your eyes become yellow in colour, especially in the first month of taking this medication - this could be jaundice (a condition affecting the liver)

When to see your doctor

While taking chlorpromazine, you should stop taking your medication and see your doctor without delay if:

  • you start to get abnormal movements that you cannot control. Antipsychotic medications can cause a wide variety of unusual movements that affect your muscles, including stiffness, spasm or tremor in the arms and legs. If the movements are severe you might find it hard to speak, eat or breathe
  • you find your eyes fixing and staring/bulging

While taking chlorpromazine, you should not stop taking your medication but should see your doctor as soon as possible if:

  • you experience strange movements of your lips and/or tongue that you cannot control. These can be quite regular and rhythmic. This condition is called tardive dyskinesia. It may start suddenly or after you have been taking the medication for some time and may be permanent, continuing even after the medication is stopped. If you notice it early and take immediate action by visiting your doctor, the problem should not get worse
  • you experience swelling, pain or redness in your leg(s), chest pain and/or difficulty breathing. This may be due to a blood clot which will need immediate treatment
  • you notice a fast or unusual heartbeat or chest pain around the heart that spreads to the shoulders, neck or arms with difficulty breathing. This could be a heart attack
  • you are feeling down or depressed, agitated or not feeling any emotion at all
  • you start having seizures (fits)
  • you experience a high temperature, chills, and ulcers in your mouth and throat, or sore throat and unusual tiredness. These can be signs of a problem in your blood
  • you feel dizzy when you stand up (this could indicate low blood pressure)
  • you feel very thirsty or notice an increase in how often you need to pee (this could be a symptom of high blood sugar)
  • you have a low body temperature
  • you are constipated (finding it hard to go for a poo) or experience a change in the times when you do this
  • you have a persistently dry mouth, stuffy nose, blurred eyesight or feel light-headed
  • you experience blurred vision
  • you begin gaining weight quickly
  • your skin becomes very sensitive to sunlight

Monitoring

While taking this medication, your doctor should carry out regular blood tests to check your liver, blood sugar and hormone levels.

They may also want to do a heart test using a machine called an electrocardiogram (ECG) if you are at risk of heart disease.

These tests should be done regularly at the beginning of your treatment, at least once every couple of weeks, and once a year after that.

Your doctor should also do blood tests to check your liver, blood sugar, and your levels of some hormones like prolactin.

Side effects

Side effects

Your medicine box contains a leaflet which describes all known side effects for your medication, both rare and common.

If you do get a side effect, please think about reporting it via the 'Yellow Card scheme'.

Some side effects of chlorpromazine should get better after a few days of taking the medication. If they don’t, you should discuss them with your doctor. Do not suddenly stop taking your tablets until you have done this, as you may get ‘kick-back’ symptoms as well as losing the benefits of your treatment.

The most common side effects of chlorpromazine (affecting up to one in ten people) are:

  • tiredness and sleeping more than usual
  • feeling woozy
  • constipation (difficulty pooing)
  • finding it difficult to pee
  • dry mouth
  • stuffy nose
  • lightheadedness
  • blurred eyesight
  • weight gain
  • skin becomes very sensitive to sunlight

Taking chlorpromazine

How long will I need to take chlorpromazine for?

Young people usually take chlorpromazine for many months or years. Your doctor should talk to you about how long you might expect to stay on this medication.

Ideally, you should stay on an antipsychotic medication for four to six weeks before deciding whether to continue taking it in the long term. This gives the medication a chance to build up in your system and to begin delivering its full effects.

Your doctor should review your progress on this medication at least once a year.

You should only take chlorpromazine as agreed with your doctor

You will get the best effect from chlorpromazine if you take it regularly at the dose prescribed by your doctor.

Make sure that you know your dose. If it's not written on the label, check with your pharmacist or doctor.

Some people start with a low dose of chlorpromazine in liquid form before moving on to tablets as their dose increases.

At the start, you may take chlorpromazine three or four times a day, but as it’s a long-acting drug, you’ll probably be able to avoid taking it during school or college hours.

If you do have to take your medication at school or college, ask your doctor to help you talk to a teacher or school nurse about how best to do this (some people prefer to keep a separate supply of medicine at school or college, for instance - your pharmacist can help with that).

Tablets and liquid can be taken before or after food. Swallow tablets whole with a drink of water – if chewed, they taste horrible!

The liquid medicine can be mixed with your favourite cold drink or added to food, if you prefer.

It’s possible to administer a fast-acting dose of chlorpromazine by injection if you’re having serious symptoms. You must visit a doctor or nurse for this and should stay lying down for 30 minutes after receiving the injection. Your blood pressure will probably be taken during this time, to check it’s within normal levels.

What if I miss a dose?

If you forget to take a dose of chlorpromazine, carry on from the next dose.

Do not take a double dose.

What will happen if I forget to take my chlorpromazine?

If you forget to take this medication for a few days, your old symptoms might start coming back. If this happens, talk to your doctor without delay.

Stopping the use of chlorpromazine

Once you start taking an antipsychotic medication, the brain adjusts to having a new level of dopamine around. If you stop taking the antipsychotic all at once, the balance starts to change again, meaning you could get your old symptoms back.

Stopping this medicine quickly, or reducing the dose too much at once, may also give you ‘kick-back’ symptoms like feeling sick, being sick, shaking, uncontrolled movements of the hands and body, and finding it hard to get to sleep.

You can stop taking chlorpromazine safely and gradually over several days or weeks with your doctor’s help.

Warnings and safety

Safety headlines

If you have taken more chlorpromazine than the dosage recommended by the doctor who prescribed it to you, you must get medical help immediately - even if you do not feel any different.

Take along a friend or family member if possible, in case you start to feel ill on the way.

You should also take your medication with you and tell the staff there how much you have taken.

When to go to the hospital

If you have taken more chlorpromazine than the dosage recommended by the doctor who prescribed it to you, you must get medical help immediately - even if you do not feel any different.

Take along a friend or family member if possible, in case you start to feel ill on the way.

You should also take your medication with you and tell the staff there how much you have taken.

Taking too much chlorpromazine may result in:

  • quick and shallow breathing
  • low body temperature
  • low blood pressure
  • restlessness
  • twisting of your arms and legs
  • seizures (fits)
  • unusual heartbeat

If you experience any of the following symptoms, you should stop taking chlorpromazine and go to the hospital straight away:

  • difficulty in swallowing, or swelling in the mouth, tongue, face and throat
  • itching, or a rash on your body (this could be an allergic reaction)
  • muscles going stiff or rigid with high fever; sweating; looking pale; feeling strange; fainting or losing consciousness; or tachycardia (very rapid or irregular heartbeat) - this may be a serious and life-threatening side effect called neuroleptic malignant syndrome
  • a painful erection that lasts for a long time (priapism)
  • skin reactions including rashes, flaking of the skin or red blisters on the skin. Remember: you need to apply a high-protection sunscreen before you go out in fine weather as chlorpromazine makes the skin more sensitive to sunlight
  • your skin and the whites of your eyes become yellow in colour, especially in the first month of taking this medication - this could be jaundice (a condition affecting the liver)

When to see your doctor

While taking chlorpromazine, you should stop taking your medication and see your doctor without delay if:

  • you start to get abnormal movements that you cannot control. Antipsychotic medications can cause a wide variety of unusual movements that affect your muscles, including stiffness, spasm or tremor in the arms and legs. If the movements are severe you might find it hard to speak, eat or breathe
  • you find your eyes fixing and staring/bulging

While taking chlorpromazine, you should not stop taking your medication but should see your doctor as soon as possible if:

  • you experience strange movements of your lips and/or tongue that you cannot control. These can be quite regular and rhythmic. This condition is called tardive dyskinesia. It may start suddenly or after you have been taking the medication for some time and may be permanent, continuing even after the medication is stopped. If you notice it early and take immediate action by visiting your doctor, the problem should not get worse
  • you experience swelling, pain or redness in your leg(s), chest pain and/or difficulty breathing. This may be due to a blood clot which will need immediate treatment
  • you notice a fast or unusual heartbeat or chest pain around the heart that spreads to the shoulders, neck or arms with difficulty breathing. This could be a heart attack
  • you are feeling down or depressed, agitated or not feeling any emotion at all
  • you start having seizures (fits)
  • you experience a high temperature, chills, and ulcers in your mouth and throat, or sore throat and unusual tiredness. These can be signs of a problem in your blood
  • you feel dizzy when you stand up (this could indicate low blood pressure)
  • you feel very thirsty or notice an increase in how often you need to pee (this could be a symptom of high blood sugar)
  • you have a low body temperature
  • you are constipated (finding it hard to go for a poo) or experience a change in the times when you do this
  • you have a persistently dry mouth, stuffy nose, blurred eyesight or feel light-headed
  • you experience blurred vision
  • you begin gaining weight quickly
  • your skin becomes very sensitive to sunlight

Monitoring

While taking this medication, your doctor should carry out regular blood tests to check your liver, blood sugar and hormone levels.

They may also want to do a heart test using a machine called an electrocardiogram (ECG) if you are at risk of heart disease.

These tests should be done regularly at the beginning of your treatment, at least once every couple of weeks, and once a year after that.

Your doctor should also do blood tests to check your liver, blood sugar, and your levels of some hormones like prolactin.

Side effects

Side effects

Your medicine box contains a leaflet which describes all known side effects for your medication, both rare and common.

If you do get a side effect, please think about reporting it via the 'Yellow Card scheme'.

Some side effects of chlorpromazine should get better after a few days of taking the medication. If they don’t, you should discuss them with your doctor. Do not suddenly stop taking your tablets until you have done this, as you may get ‘kick-back’ symptoms as well as losing the benefits of your treatment.

The most common side effects of chlorpromazine (affecting up to one in ten people) are:

  • tiredness and sleeping more than usual
  • feeling woozy
  • constipation (difficulty pooing)
  • finding it difficult to pee
  • dry mouth
  • stuffy nose
  • lightheadedness
  • blurred eyesight
  • weight gain
  • skin becomes very sensitive to sunlight

About this information

The information on this page was reviewed by the College of Mental Health Pharmacy in March 2020.

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