What it is used for

Schizophrenia
Mania in bipolar disorder, and preventing it returning

Read our guides:

Off-label uses

Doctors sometimes prescribe a medicine for a condition it is not officially licensed for. This is called off-label use. It is legal and common when there is good evidence it helps, and your doctor should explain why they are suggesting it.

Severe agitation or anxiety
Anorexia nervosa (low doses, specialist only)
Sickness in palliative care

How it works

Olanzapine blocks dopamine and serotonin receptors in the brain. This reduces symptoms such as hearing voices, paranoia and mania.

Side effects

Like all medicines, Olanzapine can cause side effects, although not everyone gets them. Many are mild and ease after the first few weeks.

Common side effects

weight gain and increased appetite
feeling sleepy
dizziness
dry mouth
constipation
raised blood sugar and cholesterol

Tell your doctor or pharmacist if these bother you or do not go away.

Serious side effects

These are rare. Call 111 or contact your doctor straight away if you get:

a high temperature with stiff muscles and confusion (neuroleptic malignant syndrome). Call 999
uncontrolled movements of the face, tongue or body
feeling very thirsty and peeing a lot, which can be signs of diabetes
signs of a blood clot, such as a painful swollen leg

Call 999 if you have signs of a serious allergic reaction, such as swelling of your lips, mouth, throat or tongue, or trouble breathing.

You can report any side effect to the Yellow Card scheme, run by the medicines regulator.

Stopping and withdrawal

Important safety information

Your weight, blood sugar and cholesterol will be checked regularly.
Smoking lowers olanzapine levels. Tell your team if you start or stop smoking.

Questions about your medicine?

A pharmacist can answer questions about your medicines for free, without an appointment. You can also ask your GP for a medication review. Check if you can get free prescriptions.