A mental condition characterized by distortions of thinking and perception, as well as inappropriate or narrowed range of emotions.


  • Not known, but there are associated biological, genetic and environmental factors

Clinical features

Any one or more of these may be diagnostic:

  • Delusions (abnormal, fixed, false beliefs) or excessive and unwarranted suspicions (may be multiple, fragmented or bizarre)
  • Disconnected ideas with vague or incoherent speech and inadequate in content
  • Hallucinations: hearing voices or seeing things that are not witnessed by others Severe behaviour abnormalities: agitation or disorganised behaviour, excitement, inactivity or overactivity
  • Disturbance of emotions such as marked apathy or disconnection between reported emotions and observed
  • Mood is usually inappropriate
  • Difficulty in forming and sustaining relationships
  • Social withdrawal and neglect of usual responsibilities

Chronic psychosis or schizophrenia

  • Symptoms of psychosis lasting for 3 or more months
  • Accompanied by deterioration in social, general and occupational functioning

Differential diagnosis

  • Alcohol and drug intoxication or withdrawal
  • Organic delirium, dementia, mood disorders


  • Good social, personal and family history
  • Laboratory investigations for infectious diseases e.g. HIV, syphilis


Acute psychosis

  • Counselling/psychoeducation of patient and carers

Antipsychotic drugs

  • Chlorpromazine: starting dose 75-150 mg daily and maintenance dose of 75-300 mg daily. Up to
    1000 mg daily in divided does may be required for those with severe disturbance
  • Or Haloperidol: starting dose 5-10 mg daily (lower in elderly) and maintenance dose of 5-20
    mg daily in divided doses
  • Administer orally or IM for those with agitation
  • Only use one antipsychotic at a time
  • Gradually adjust doses depending on response
  • Monitor for side effects e.g. extrapyramidal side effects
  • Use therapeutic dose for 4-6 weeks to assess effect
  • Psychological interventions (family therapy or social skills therapy) if available
  • Ensure follow up
  • For acute psychosis, continue treatment for at least 12 months. Discuss discontinuation with
    patient, carers and specialist

If extrapyramidal side-effects

  • Add an anticholinergic: Benzhexol initially 2 mg every 12 hours then reduce gradually to once daily
    and eventually give 2 mg only when required

If no response

  • Refer to specialist

Chronic psychosis

Treat as above, but if adherence is a problem or the patient prefers, use:

  • Fluphenazine decanoate 12.5-50 mg every 2-5 weeks deep IM into gluteal muscle
  • Or Haloperidol injection (oily) 50-200 mg (300 mg) deep IM into gluteal muscle every 3-4 weeks