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  • Olanzapine can cause drowsiness and dizziness. If this happens, make sure your reactions are normal before you drive or use tools or machines.
  • Keep your regular appointment with your doctor so your progress can be checked.
  • Olanzapine may cause your skin to become more sensitive to sunlight than normal. Use a sunscreen to protect your skin.
Type of medicineAntipsychotic
Used forEasing the symptoms of schizophrenia and other similar mental health problems
Also calledArkolamyl®
Available asTablets, Velotabs® (dissolve in the mouth tablets), and injection

Schizophrenia is a serious mental health condition that causes disordered ideas, beliefs and experiences. Olanzapine is used to relieve the symptoms of schizophrenia and other similar mental health problems. Such symptoms include hearing, seeing, or sensing things that are not real, having mistaken beliefs, and feeling unusually suspicious.

Olanzapine works on the balance of chemical substances in your brain.

Olanzapine is also available as a long-acting or 'depot' injection. This injection is given every few weeks and slowly releases olanzapine so that you do not have to remember to take tablets every day. There is another medicine leaflet called 'Olanzapine long-acting injection' which gives more information about this.

Some medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken. For these reasons, before you start taking olanzapine, it is important that your doctor knows:

  • If you are pregnant, trying for a baby or breast-feeding.
  • If you have a heart condition or blood vessel disease.
  • If you have liver, kidney, or prostate problems.
  • If you have breathing problems.
  • If you have any of the following: diabetes, epilepsy, Parkinson's disease, depression, glaucoma, or myasthenia gravis (this is a condition causing muscle weakness).
  • If you have a blood or bone marrow disorder.
  • If you are constipated or think you may have a blockage in your bowel.
  • If you have ever had jaundice (yellowing of your skin and the whites of your eyes).
  • If you have a condition called phaeochromocytoma (a tumour on your adrenal gland).
  • If you have ever had an allergic reaction to any medicine.
  • If you are taking or using any other medicines. This includes any medicines you are taking which are available to buy without a prescription, such as herbal and complementary medicines.
  • Before you start this treatment, read the manufacturer's printed information leaflet from inside your pack. The leaflet will give you more information about the specific brand of olanzapine you have been given, and a full list of possible side-effects from taking it.
  • Take olanzapine exactly as your doctor has told you. It is taken once each day. Your dose will also be on the label of the pack. You can take olanzapine before or after your meals.
  • Try to take olanzapine at the same time each day, as this will help you to remember to take it. If you do forget to take a dose, take it as soon as you remember (unless it is nearly time for your next dose, in which case leave out the missed dose). Do not take two doses together to make up for a forgotten dose.
  • If you have been given Zalasta® orodispersible tablets or Zyprexa® Velotabs, these are tablets which dissolve in your mouth. Do not try pushing the tablet through the blister of the packaging as it may crumble; instead, peel open the packaging, remove the tablet from the blister and place it on your tongue to dissolve. Or if you prefer, you can dissolve the tablet in a glass of water and then drink it straightaway.
  • Your treatment will require careful monitoring to make sure that you get the best possible benefit from olanzapine. Keep your regular doctor's appointments so that your progress can be checked. You will need to have some tests from time to time.
  • Treatment with olanzapine is usually long-term unless you experience an adverse effect. Keep taking these tablets until your doctor tells you otherwise. Stopping suddenly can cause problems and your doctor may want you to reduce your dose gradually if this is necessary.
  • Olanzapine may cause your skin to become more sensitive to sunlight than normal. Use a sunscreen that protects against UVA light and has a sun protection factor (SPF) of at least 15, especially in strong sunlight or until you know how your skin reacts. Do not use sunbeds.
  • If you drink alcohol, ask your doctor for advice about drinking while you are on olanzapine. Alcohol will increase the chance that you experience side-effects and may not be recommended for you.
  • If you have diabetes you may need to check your blood glucose more frequently, as olanzapine may affect the levels of sugar in your blood. Your doctor will be able to advise you about this.
  • If you are having any dental treatment or an operation, tell the person carrying out the treatment which medicines you are taking. This is important because olanzapine may interfere with any anaesthetic you receive.
  • If you buy or take any 'over-the-counter' medicines, check with a pharmacist that they are safe to take with olanzapine.

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. These usually improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following side-effects continue or become troublesome.

Common olanzapine side-effects - these affect about 1 in 10 people who take this medicineWhat can I do if I experience this?
Feeling sleepy, dizzy, or light-headedIf this happens, do not drive or use tools or machines
ConstipationDrink plenty of water, and eat a well-balanced diet containing plenty of fruit, vegetables, and fibre
Dry mouthTry chewing sugar-free gum or sucking sugar-free sweets
Increased appetite and weight, unusual movements, shaking, skin rash, feeling tired or weak, reduced interest in sex and erectile dysfunctionDiscuss these with your doctor if any become troublesome

Important: if you experience any 'flu-like' symptoms including muscle stiffness, with a high temperature, confusion, a fast heartbeat and sweating, contact your doctor immediately. These may be signs of a rare but serious condition known as neuroleptic malignant syndrome.

Important: if you develop any abnormal face or body movements, or feel very restless, speak with your doctor about this as soon as possible.

If you experience any other symptoms which you think may be due to this medicine, speak with your doctor or pharmacist.

  • Keep all medicines out of the reach and sight of children.
  • Store in a cool, dry place, away from direct heat and light.
  • Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.
  • This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.
  • Never keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.
  • If you have any questions about this medicine ask your pharmacist.

Further reading & references

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

Original Author:
Helen Allen
Current Version:
Peer Reviewer:
Dr Helen Huins
Document ID:
1432 (v23)
Last Checked:
Next Review:
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