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    Last updated: February 2024


    Prescription under medical supervision


    Due to the numerous and potentially severe adverse effects of olanzapine, patients should be kept under close surveillance.


    Therapeutic action

    • Atypical antipsychotic


    • Acute and chronic psychosis and acute manic episode, in the event of intolerance or treatment failure with other antipsychotics (preferably use haloperidol for these indications) 

    Forms and strengths

    • 2.5 mg, 5 mg and 10 mg tablets


    • Adult: 10 mg once daily. Increase up to 15 mg daily if necessary (max. 20 mg daily).
    • Reduce the dose by half in older patients (max. 10 mg daily).


    • Acute psychosis: at least 3 months
    • Chronic psychosis: at least one year
    • Manic episode: 8 weeks after remission of symptoms


    Discontinue treatment gradually (over 4 weeks). If signs of relapse occur, increase the dose then decrease it more gradually. 

    Contra-indications, adverse effects, precautions

    • Do not administer to patients with cardiac disorders (heart failure, recent myocardial infarction, conduction disorders, bradycardia, etc.), dementia (e.g. Alzheimer's disease), Parkinson's disease, history of neuroleptic malignant syndrome and closed-angle glaucoma.
    • Administer with caution and carefully monitor use in older patients and patients with hypokalaemia, hypotension, prostate disorders, renal or hepatic impairment, history of seizures. 
    • May cause: orthostatic hypotension, drowsiness (caution when driving/operating machinery), extrapyramidal symptoms, hyperprolactinaemia, weight gain, hyperlipidaemia, hyperglycaemia, anticholinergic effects (constipation, dry mouth), headache, insomnia, dizziness, sexual dysfunction; neuroleptic malignant syndrome (unexplained hyperthermia with neuromuscular disorders), rare but requiring immediate treatment discontinuation. 
    • In case of extrapyramidal symptoms, try reducing the dose of olanzapine or, if the extrapyramidal symptoms are severe, add biperiden or trihexyphenidyl.
    • Avoid or monitor combination with:
      • central nervous system depressants (opioid analgesics, sedatives, H1 antihistamines, etc.); 
      • ciprofloxacin (increased plasma concentrations of olanzapine);
      • carbamazepine, rifampicin, phenobarbital, phenytoin, ritonavir (decreased plasma concentrations of olanzapine);
      • antihypertensive drugs (risk of hypotension); drugs that prolong the QT interval (amiodarone, chloroquine, erythromycin, fluconazole, mefloquine, pentamidine, quinine, etc.). 
    • Avoid alcohol during treatment (increased risk of adverse effects).
    • Pregnancy: re-evaluate whether the treatment is still necessary; if it is continued, use the lowest effective dose. Observe the neonate the first few days (risk of agitation, tremors, hypertonia/hypotonia, respiratory difficulties, sleeping disorders, etc.) if the mother was under treatment in the 3rd trimester. If treatment starts during pregnancy, preferably use haloperidol.
    • Breast-feeding: if absolutely necessary, do not exceed 10 mg daily. 


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