Olanzapine (Arkolamyl, Zalasta, Zyprexa)

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Olanzapine belongs to a group of medicines called antipsychotics. It is taken once daily.

Keep your regular appointments with your doctor. This is so your progress can be checked.

The most common side-effects include feeling sleepy or dizzy, and increased weight.

Type of medicine An antipsychotic medicine
Used for Easing the symptoms of schizophrenia and mania; preventing high mood swings in bipolar disorder
Also called Arkolamyl®; Zalasta®; Zyprexa®
Available as Tablets, and melt-in-the-mouth (orodispersible) tablets

Olanzapine belongs to a group of medicines called antipsychotics. It may have been prescribed for you to relieve the symptoms of schizophrenia, or alternatively, it may have been prescribed for the treatment and/or prevention of high mood swings (mania). In both of these conditions, olanzapine works on the balance of chemical substances in your brain.

Maintenance doses of olanzapine can also be given to people with schizophrenia by depot injection. There is a separate medicine leaflet providing more information about this, called Olanzapine long-acting injection.

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 or breast-feeding.
  • If you have a heart condition or blood vessel disease.
  • If you have liver, kidney, or prostate problems.
  • If you have any problems with your breathing.
  • If you are very constipated or think you may have a blockage in your bowel.
  • If you have any of the following: epilepsy, sugar diabetes, depression, Parkinson's disease, raised pressure in your eye (glaucoma) or a condition which causes muscle weakness, called myasthenia gravis.
  • If you have ever had yellowing of your skin or the whites of your eyes (jaundice).
  • If you have a blood or bone marrow disorder.
  • If you have a tumour on your adrenal gland (a condition called phaeochromocytoma).
  • If you have had an allergic reaction to a 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 the treatment, read the manufacturer's printed information leaflet from inside the pack. It will give you more information about olanzapine and it will also provide you with a full list of the side-effects which you may experience from taking it.
  • Your dose will be adjusted to suit your condition, so take olanzapine tablets exactly as your doctor tells you to. It is usual to be prescribed one dose to take each day. Your dose will be printed on the label of your pack to remind you about what the doctor said to you.
  • You can take olanzapine tablets either before or after meals.
  • Try to get into the habit of taking your dose at the same time of day 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. If you do not remember until the following day then skip the missed dose but remember to take the dose that is due on that day. Do not take two doses at the same time to make up for a forgotten dose.
  • If you have been given orodispersible tablets (Zalasta® orodispersible tablets or Zyprexa® Velotabs) - these are tablets which dissolve in your mouth - place the tablet on your tongue and allow it to dissolve. Alternatively, if you prefer, you can take the orodispersible tablet stirred into a small glassful of any of the following drinks: water, orange or apple juice, milk or coffee.
  • 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 it unless your doctor tells you otherwise. Stopping olanzapine suddenly can cause problems, so your doctor may want you to reduce your dose gradually if this becomes necessary.
  • If you drink alcohol, ask your doctor for advice. Alcohol increases the risk of side-effects from olanzapine so it is best avoided.
  • 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 advise you about this.
  • Some medicines similar to olanzapine can cause the skin to become more sensitive to sunlight than normal. It may be advisable to use a sunscreen in bright sunlight until you know how your skin reacts.
  • Smoking may affect the amount of olanzapine in your body. Let your doctor know if you either start or stop smoking while you are taking olanzapine.
  • A small number of people taking medicines for mood disorders can have thoughts about harming themselves or ending their lives, particularly when a new medicine is started. It is very important that you tell your doctor about this if it happens to you.
  • If you are due to have any medical or dental treatment, 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 or herbal remedies, please check with a pharmacist that they are suitable for you to take with olanzapine.

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the most common ones associated with olanzapine. You will find a full list in the manufacturer's information leaflet supplied with your medicine. The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following continue or become troublesome.

Very common olanzapine side-effects (these affect more than 1 in 10 people) What can I do if I experience this?
Feeling sleepy or dizzy Do not drive or use tools or machines
Increased weight Eat a well-balanced diet. Speak with your doctor if your weight becomes troublesome
Changes to some blood test results Your doctor will monitor for these
Common olanzapine side-effects (these affect less than 1 in 10 people) What can I do if I experience this?
Feeling restless or tired Speak with your doctor about this. Do not drive or use tools or machines while affected
Constipation Drink plenty of water and eat a well-balanced diet
Dry mouth Try chewing sugar-free gum or sucking sugar-free sweets
Unusual or uncontrollable muscle movements Speak with your doctor about these
Increased appetite, feeling hot, swollen hands or feet, skin rash, reduced interest in sex, erectile dysfunction, aches and pains Discuss these with your doctor if any become troublesome

Important: if you experience symptoms such as muscle stiffness, a very high temperature, feeling confused, a fast heartbeat and sweating, you should contact your doctor immediately. These can be signs of a rare but serious condition known as neuroleptic malignant syndrome.

If you experience any other symptoms which you think may be due to the tablets, please speak with your doctor or pharmacist for further advice.

  • 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.

Do not 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 (v24)
Last Checked:
29/07/2015
Next Review:
28/07/2018
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