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    Last updated: April 2024


    Prescription under medical supervision


    Therapeutic action

    • Sedating H1 antihistamine


    • Agitation or aggressive behaviour in patients with acute or chronic psychosis, in combination with haloperidol

    Forms and strengths, route of administration

    • 50 mg in 2 ml ampoule (25 mg/ml) for deep IM injection. 

    Dosage and duration

    • Adult: 25 mg, to be repeated after 30 minutes if necessary. If no response 30 minutes after the second dose, administer 50 mg (total dose max. 100 mg).

    Contra-indications, adverse effects, precautions

    • Administer with caution and monitor use:
      • in older patients; 
      • in patients with prostate disorders, closed-angle glaucoma, epilepsy, orthostatic hypotension, severe renal or hepatic impairment;
      • in patients taking central nervous system depressants (opioid analgesics, antipsychotics, sedatives, antidepressants, etc.) or drugs known to have an anticholinergic effect (atropine, amitriptyline, chlorpromazine, etc.).
    • May cause:
      • drowsiness, dizziness, headache, confusional state, hypotension, photosensitivity (protect skin from sun exposure); 
      • anticholinergic effects (dry mouth, constipation, blurred vision, tachycardia, disorders of micturition); 
      • tissue damage, including necrosis; 
      • rarely: seizures, extrapyramidal syndrome, neuroleptic malignant syndrome (unexplained hyperthermia with neuromuscular disorders), allergic reactions.
    • Pregnancy and breast-feeding: avoid


    • Promethazine by IV route should only be used in intensive care unit, at a max. concentration of 1 mg/ml by infusion over 20 minutes using a central catheter or a large bore peripheral catheter (risk of necrosis and peripheral gangrene).
    • Promethazine is not included in the WHO list of essential medicines. 


    –  Below 25 °C