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.
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
Like all medicines, olanzapine can cause side effects, although not everyone gets them.
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)
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.
- 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
- 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
In rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to olanzapine.
These are not all the side effects of olanzapine. For a full list see the leaflet inside your medicines packet.
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
- constipation – eat 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.
Pregnancy and breastfeeding
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.
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
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.
Bipolar disorder — Link to Related Condition
Schizophrenia — Link to Related Condition
HealthUnlocked: olanzapine forum — Link to Useful Resource
Bipolar UK: charity — Link to Useful Resource
Mind: charity — Link to Useful Resource
Rethink Mental Illness: charity — Link to Useful Resource
Young Minds - Medications: charity — Link to Useful Resource
HealthUnlocked contains information from NHS Digital, licensed under the current version of the Open Government Licence