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Antipsychotic (atypical / second-generation)

Olanzapine: uses, side effects & precautions

Also known as Zyprexa.

Esta información es solo orientativa de carácter general y no constituye un consejo médico. Consulta siempre a un profesional sanitario cualificado para cualquier asunto médico personal. En caso de emergencia, llama al número de emergencias de tu zona.

What it is used for

  • Schizophrenia
  • Bipolar disorder (mania and maintenance)
  • Sometimes used to help with severe agitation or nausea in specific settings

How it works

Olanzapine acts on dopamine and serotonin signalling in the brain, helping to rebalance the chemical messengers involved in thinking, mood and perception.

How it is taken

Usually available as standard tablets, orodispersible tablets that dissolve in the mouth, and a long-acting injection given by a healthcare professional. The oral form is taken by mouth. Take it exactly as your doctor or pharmacist directs and follow the label; do not stop suddenly.

No doses here on purpose. The right strength and schedule depend on you — only a doctor or pharmacist should set them. Always follow your prescription and the label.

Common side effects

  • Drowsiness
  • Weight gain
  • Increased appetite
  • Dizziness
  • Dry mouth
  • Constipation
  • Tiredness
  • Swelling of hands or feet

Serious effects — get help

  • Signs of high blood sugar or diabetes: excessive thirst, frequent urination, weakness
  • Marked weight gain and raised blood fats
  • Neuroleptic malignant syndrome: high fever, severe muscle stiffness, confusion (medical emergency)
  • Uncontrolled movements of the face or body (may persist)
  • Irregular heartbeat or fainting
  • Signs of low white blood cells: fever, sore throat, infections
  • New or worsening suicidal thoughts

If a reaction is severe — for example trouble breathing, swelling of the face or throat, or collapse — go to the nearest emergency room now or call your local emergency number. Do not wait for an online consultation.

Interactions to watch

  • Alcohol and other sedating medicines (added drowsiness)
  • Medicines that affect heart rhythm
  • Some medicines that change how the liver processes it (smoking can also lower its levels)
  • Blood-pressure medicines

Who should take care

  • Commonly causes weight gain and can affect blood sugar and fats, which may be monitored
  • Use with caution with diabetes, heart conditions, seizures or in older adults with dementia (higher risks)
  • Tell your clinician if you are pregnant, planning pregnancy or breastfeeding
  • Starting or stopping smoking can change how much medicine is in your body - tell your clinician
  • Do not stop suddenly; taper under medical guidance

Frequently asked questions

Does olanzapine cause a lot of weight gain?
It is among the antipsychotics more likely to increase appetite and weight and to affect blood sugar and fats. Your clinician will weigh this against its benefits and may monitor these measures.
How does smoking affect it?
Tobacco smoke can lower olanzapine levels in the body. Starting or stopping smoking can change how much effect you get, so tell your clinician if your smoking changes.
What is the long-acting injection for?
A long-acting injection given by a healthcare professional can help people who prefer not to take daily tablets. It requires monitoring after each dose in a clinical setting.
What is neuroleptic malignant syndrome?
It is a rare but serious reaction with high fever, severe muscle stiffness, confusion and a fast heartbeat. It is a medical emergency - seek immediate care.
Is Olanzapine safe to take?
For most people it is safe when taken exactly as a doctor or pharmacist advises and as printed on the label. Tell your clinician about your other medicines and health conditions, and seek urgent care for any serious reaction.

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