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Olanzapine - Brand names: Zyprexa, Zentiva

On this page

  1. About olanzapine
  2. Key facts
  3. Who can and cannot use olanzapine
  4. How and when to take olanzapine
  5. Side effects
  6. How to cope with side effects of olanzapine
  7. Pregnancy and breastfeeding
  8. Cautions with other medicines
  9. Common questions about olanzapine

1. About olanzapine

Olanzapine helps to manage symptoms of mental health conditions such as:

  • seeing, hearing, feeling or believing things that others do not, feeling unusually suspicious or having muddled thoughts (schizophrenia)
  • feeling agitated or hyperactive, very excited, elated, or impulsive (mania symptoms of bipolar disorder)

If you have bipolar disorder, olanzapine can also stop your mania symptoms coming back.

Olanzapine does not cure your condition, but it can help with your symptoms.

Olanzapine comes as tablets, including tablets that dissolve in your mouth (orodispersible), and an injection.

Olanzapine is only available with a prescription.

2. Key facts

  • Olanzapine does not work straight away. It may take several days, or even weeks, for some of your symptoms to start improving.
  • Soon after you first start taking olanzapine, before your other symptoms improve, it may make you feel more relaxed and calm.
  • Common side effects include: feeling sleepy, feeling dizzy, and constipation.
  • Olanzapine belongs to a group of medicines called antipsychotics. It works by affecting the naturally occurring chemical messengers in your brain (neurotransmitters), like dopamine and serotonin.
  • It’s important to keep taking your medicine even if you feel better, unless your doctor asks you to stop.

3. Who can and cannot use olanzapine

Olanzapine can be taken by adults aged 18 years and over.

Olanzapine is not suitable for some people. To make sure it’s safe for you, tell your doctor before starting the medicine if you:

  • have ever had an allergic reaction to olanzapine or any other medicine
  • have a heart problem, including an irregular heartbeat (arrhythmia)
  • have low blood pressure
  • have had a stroke or are at high risk of having a stroke
  • have had a blood clot or someone in your family has had blood clots
  • have ever had problems controlling the movements of your tongue, mouth and face
  • have ever had a rare condition called neuroleptic malignant syndrome
  • have Parkinson’s disease or dementia
  • have ever had low levels of white blood cells
  • have diabetes
  • have epilepsy
  • have liver or kidney problems
  • have an abnormally high level of the hormone, prolactin in your blood or if you have a possible prolactin-dependent tumour
  • have glaucoma (increased pressure in the eye)
  • are very constipated or you think you have a blockage in your bowels

4. How and when to take olanzapine

Olanzapine is a prescription medicine. It’s important to take it as your doctor tells you.

Dosage and strength

Olanzapine tablets come in different strengths: 2.5mg, 5mg, 7.5mg, 10mg, 15mg and 20mg.

How much you take will depend on what you’re taking it for. Your doctor may ask you to adjust your dose depending on how well olanzapine works for you.

If you have problems with your kidneys or liver, your doctor may ask you to take a lower dose and increase your dose very slowly.

Dosage for schizophrenia

The usual starting dose for:

  • adults aged 64 and younger is 10mg, taken once a day
  • adults aged 65 or over is 5mg, taken once a day

Dosage for mania symptoms of bipolar disorder

You’ll usually start on 15mg, taken once a day. If you’re taking other medicines to help your symptoms, you may start on 10mg.

Dosage to prevent mania symptoms coming back

You’ll usually start on a dose of 10mg, taken once a day. If you have been taking olanzapine to treat your mania symptoms, you may stay on the same dose.

How to take olanzapine

Take olanzapine once a day, at the same time each day.

You can take it with or without food.

How to take tablets

Swallow your tablet whole with a drink of water.

How to take tablets that dissolve in your mouth (orodispersible)

Place the tablet on your tongue and let it dissolve. You can have a drink of water afterwards if you want.

You can also put the tablet into a small glass of water, orange juice, apple juice or milk. Stir the mixture well until the tablet is dissolved and then drink all of it straight away to make sure you get the full dose.

How to have injections

Injections are given into the muscle of your buttock every 2 to 4 weeks by a doctor or nurse. This would usually be in a specialist clinic.

Will my dose go up or down?

Your doctor may ask you to increase or decrease your dose, but this will depend on how well olanzapine works to help manage your symptoms.

Most people feel better with daily doses of 5mg to 20mg. It may take a few weeks to get to the right dose that works for you.

What if I forget to take it?

If you forget a dose of olanzapine, take it as soon as you remember, unless you only remember the next day. In this case, skip the missed dose and take your next dose at the usual time.

Contact your doctor if you miss 2 or more doses.

Do not take 2 doses at the same time 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?

Taking too much olanzapine can lead to serious side effects.

Urgent advice: Contact 111 for advice now if:

You take more than your prescribed dose of olanzapine and:

  • feel sleepy or tired
  • have unusual body movements, especially face or tongue movements
  • have problems standing and walking
  • feel dizzy

Call 111 or visit 111.nhs.uk

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 olanzapine packet or leaflet inside it, plus any remaining medicine with you.

Immediate action required: Call 999 or go to A&E if:

You take more than your prescribed dose of olanzapine and:

  • have a fast or irregular heartbeats
  • have a seizure or fit
  • start having problems with your speech
  • have fast or slow breathing

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

5. Side effects

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

Common side effects

These common side effects may affect up to 1 in 10 people. Tell your doctor if these side effects bother you or do not go away:

  • feeling sleepy in the day
  • putting on weight or an increase in your appetite
  • feeling dizzy (especially when getting up from a sitting or lying position)
  • rash
  • constipation

See your doctor if you have:

  • sexual problems such as lower libido in men and women, or problems getting an erection – these can be signs of hormone changes
  • problems with your movement
  • infections including coughs, colds and chest infections, ear and eye infections, or urinary tract infections (UTIs) – these can be signs of a low white blood cell count

Serious side effects

Serious side effects are rare and happen in less than 1 in 1,000 people.

Urgent advice: Contact 111 for advice now if:

  • you get twitching or jerking movements in your face, tongue or other parts of your body
  • you start shuffling slowly when you walk, trembling or drooling

Call 111 or go to 111.nhs.uk

Immediate action required: Call 999 or go to A&E if:

  • you get swelling, pain and redness in one leg, or chest pain with difficulty breathing – these may be signs of blood clots
  • you have weakness on one side of your face or body, trouble speaking or thinking, or blurred eyesight – these can be signs of a stroke
  • you have a high temperature, muscle stiffness, sweating, anxiety or excess saliva – these can be signs of neuroleptic malignant syndrome
  • you get a painful erection (priapism) lasting more than 2 hours

Serious allergic reaction

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

Immediate action required: Call 999 or go to A&E now if:
  • you get a skin rash that may include itchy, red, swollen, blistered or peeling skin
  • you're wheezing
  • you get tightness in the chest or throat
  • you have trouble breathing or talking
  • your mouth, face, lips, tongue or throat start swelling

You could be having a serious allergic reaction and may need immediate treatment in hospital.

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

Information:

You can report any suspected side effect using the Yellow Card safety scheme.

Visit Yellow Card for further information.

6. How to cope with side effects of olanzapine

What to do about:

  • feeling sleepy in the day – do not drive, cycle or use tools or machinery if you're feeling this way. Do not drink alcohol as this will make you feel more tired. As your body gets used to olanzapine, these side effects should wear off. If they do not get better after a few weeks, speak to your doctor.
  • putting on weight or an increase in your appetite – try to eat a healthy, balanced diet without increasing your portion sizes. Do not snack on foods that contain a lot of calories, such as crisps, cakes, biscuits and sweets. If you feel hungry between meals, eat fruit and vegetables and low-calorie foods. Regular exercise will also help to keep your weight stable.
  • feeling dizzy when standing up – stand up slowly and hold on to something to steady your balance until your dizziness has passed. It should only last a few moments. As you get used to your medicine this problem should wear off.
  • rash – it may help to take an antihistamine which you can buy from a pharmacy. Ask your pharmacist which type is suitable for you to take while you are on olanzapine
  • constipationeat more high-fibre foods such as fresh fruit, vegetables and cereals. Try to drink several glasses of water or another non-alcoholic liquid every day. If you can, it may also help to increase your exercise.
  • sexual problems – see your doctor.
  • problems with your movement – see your doctor.
  • infections – see your doctor.

7. Pregnancy and breastfeeding

Olanzapine and pregnancy

Olanzapine can be taken during pregnancy and is not thought to be harmful to your baby. Your mental health and wellbeing are important.

If you become pregnant while taking olanzapine, speak to your doctor. You will be reviewed in a specialised antenatal clinic and you can discuss your medicine with the doctors in the clinic.

Do not stop taking your medicine unless your doctor tells you to.

Olanzapine and breastfeeding

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

Olanzapine passes into breast milk in very small amounts and has been linked with side effects in very few breastfed babies. Many people have used it while breastfeeding without any problems.

It's important to keep taking olanzapine to keep you well. Breastfeeding will also benefit both you and your baby.

If you notice that 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 health visitor, midwife, pharmacist or doctor as soon as possible.

Non-urgent advice: Tell your doctor if you're:

  • trying to get pregnant
  • pregnant
  • breastfeeding

For more information about how olanzapine can affect you and your baby during pregnancy, read this leaflet on the Best Use of Medicines in Pregnancy (BUMPS) website.

8. Cautions with other medicines

There are some medicines that may affect how olanzapine works.

Tell your doctor or pharmacist if you’re taking:

  • carbamazepine, a medicine for epilepsy
  • fluvoxamine, used to treat depression
  • ciprofloxacin, an antibiotic
  • medicines that make you feel calm or sleepy including benzodiazepines, painkillers like morphine or tramadol, or antihistamines like chlorphenamine – olanzapine can increase the effects of these medicines and make you feel more sleepy

Mixing olanzapine with herbal remedies and supplements

Cannabidiol (also known as CBD) might affect how olanzapine works. Do not take cannabidiol while you are taking olanzapine.

There might be a problem taking some other herbal remedies and supplements with olanzapine, especially ones that make you feel sleepy or dizzy.

Medicine safety

Tell your doctor or pharmacist if you're taking any other medicines, including herbal medicines, vitamins or supplements.

9. Common questions about olanzapine

How does olanzapine work?

Olanzapine belongs to a group of medicines called antipsychotics. It does not cure your condition, but it can help to improve the symptoms of mental health conditions.

Olanzapine works by affecting naturally occurring chemical messengers in your brain (neurotransmitters), like dopamine.

If you have too much dopamine it can make you see or hear things that are not there (hallucinations), or think things that others do not (delusions). Dopamine is also involved in muscle movements, so too much of it can affect your muscles.

Olanzapine also works on other neurotransmitters such as serotonin and noradrenaline. Olanzapine rebalances these to improve your mood and behaviour.

Taking olanzapine will not change your personality and it is not addictive.

How long does it take to work?

Olanzapine, like many medicines, does not work straight away. It can take a few weeks to get the dose right for you.

It may take several days or even weeks for some of your symptoms to get better.

How long will I take it for?

This will depend on why you need olanzapine.

If you’re taking olanzapine for:

  • schizophrenia – you may need to take olanzapine for a long time, and some people take it for years
  • bipolar disorder – you may need to take olanzapine for a few weeks or months

Carry on taking your medicine for as long as your doctor tells you to, even if you feel better. Do not stop taking your medicine without talking to your doctor first.

How will olanzapine make me feel?

When you first start taking olanzapine, it may make you feel more relaxed and calm. Within 2 to 3 weeks, your other symptoms may start to improve.

You may find olanzapine makes you:

  • able to concentrate better, and think more clearly
  • able to get things done and stay focused
  • remember things more easily
  • feel more comfortable with other people and get along with them better
  • more aware of what is real and what is not real
  • stop hearing voices
Can I take olanzapine for a long time?

Yes, many people take olanzapine for a long time, including for many months or years, without any problems.

Olanzapine can increase the amount of sugar in your blood and this can sometimes lead to diabetes. Keeping to a healthy weight can help to prevent this. It’s not a common side effect of olanzapine and affects less than 1 in 100 people.

You will usually have a blood test before you start olanzapine treatment to see how much sugar you have in your blood.

You will have another test around 12 weeks after starting olanzapine to see if the amount of sugar in your blood has changed. If it’s OK, then you will have a test each year to check your blood sugar.

If you already have diabetes you will be monitored more closely and will have more regular blood sugar tests. For example, you may have a test every 4 weeks to start with and then around 4 times a year.

Taking olanzapine for a long time can sometimes affect your cholesterol. If this happens, you may need to take a statin to help lower your cholesterol.

What will happen if I stop taking it?

Olanzapine helps to control your symptoms. Do not stop taking olanzapine suddenly otherwise your symptoms may come back.

If you need to stop taking olanzapine, your doctor will help you come off it by reducing your dose gradually. This will help prevent withdrawal symptoms.

Withdrawal symptoms include:

  • feeling or being sick
  • sweating
  • difficulty sleeping

Talk to your doctor first if you want to go onto a lower dose or to stop taking olanzapine.

How does it compare with other antipsychotic medicines?

The antipsychotic medicine you are prescribed will depend on the type of symptoms you have, how bad your symptoms are, any other medical conditions you have and how well your medicine works for you.

It will also depend on whether it’s best for you to take your medicine as tablets or an injection, and whether the medicine has any side effects that may affect you.

You may have to try a few before you find the antipsychotic medicine that is right for you. It can take time to find the right type and dose to manage your symptoms.

Different antipsychotic medicines have different side effects. When deciding on the best medicine for you, it’s important to discuss with your doctor what the possible side effects are and how they may affect you.

How does olanzapine compare to lithium for bipolar disorder?

Lithium is usually the first medicine used to treat bipolar disorder. It’s a long-term treatment for episodes of mania and depression and is often prescribed for at least 6 months.

Lithium is a mood stabiliser, which means it helps to balance your mood and control symptoms of mania as well as depression.

Olanzapine also helps with symptoms of mania. However, you will need to take it with another medicine to also manage your depression symptoms.

You can discuss with your doctor which treatment will be best for you. It will depend on the type of symptoms you have, any other medical conditions you have and whether you might be more likely to have side effects with some medicines.

Can olanzapine be used to treat anxiety?

There’s been some research into using olanzapine for anxiety, but this medicine has not yet been approved as a treatment.

Your doctor will use other medicines as a first choice if you have anxiety.

Can I drink alcohol with it?

It’s best not to drink alcohol for the first few days of treatment, until you see how the medicine affects you.

If you drink alcohol while taking olanzapine it may make you feel sleepy and unsteady on your feet.

Drinking alcohol every day or in large amounts can make your symptoms worse. It also makes it harder for olanzapine to work properly.

Will I gain or lose weight?

You will not usually lose weight on olanzapine. It can make you feel more hungry than usual, so you may put on weight.

Try to eat a healthy balanced diet, without increasing your portion sizes.

Do not snack on foods that contain a lot of calories, such as crisps, cakes, biscuits and sweets. If you feel hungry between meals, eat fruit and vegetables and low-calorie foods.

If you are worried about gaining or losing weight while taking olanzapine, talk to your doctor or pharmacist.

Is there any food or drink I need to avoid?

Apart from limiting alcohol, you can eat and drink normally while taking olanzapine.

However, olanzapine can make you feel hungrier and put on weight.

If you have an increased appetite, try to eat a healthy balanced diet without increasing your portion sizes.

Do not snack on foods that contain a lot of calories, such as crisps, cakes, biscuits and sweets. If you feel hungry between meals, eat fruit and vegetables and low-calorie foods.

Will it affect my contraception?

Olanzapine will not affect any type of contraception, including the combined pill or emergency contraception.

Will it affect my fertility?

Olanzapine can affect your hormones and sometimes causes sexual problems, such as less interest in sex (reduced libido) in men or women, and problems getting an erection. It can also affect periods.

These effects happen in fewer than 1 in 10 people.

If you would like to start a family, then talk to your doctor if you have any of these problems or if you have any concerns.

Can olanzapine affect my sex life?

Olanzapine is a type of medicine called an antipsychotic. Most antipsychotic medicines can cause sexual problems, but some are more likely to cause problems than others.

If you feel you have a sexual problem of any kind while taking olanzapine, including less interest in sex (reduced libido) or problems getting an erection, talk to your doctor. Your doctor will be able to help you and may change your olanzapine treatment so that the sexual problems improve or go away.

Can I drive or ride a bike?

Olanzapine can make you feel sleepy. If this happens to you, do not drive, ride a bike or use tools or machinery until you feel better.

Some people find it hard to concentrate while they are taking olanzapine. When you first start taking it, it's a good idea to stop driving and cycling for the first few days until you know how the medicine makes you feel.

Related conditions

Page last reviewed: 27 July 2021
Next review due: 27 July 2024