Substance Induced Psychosis

Clinical Description

Development of psychotic symptoms related to prolonged use of psycho- active drugs (eg cannabis) within the last month

Signs and Symptoms

• Hallucinations (often auditory but can be visual etc) and delusions (fixed false belief) often paranoid/ suspicious in nature
• Speech can be irrelevant and incoherent
• Abnormal behaviour and at times agitation and aggression
• Lack of insight is prominent

Investigations

• Physical causes for the symptoms must be excluded (as described in schizophrenia)
• FBC
• VDRL
• Urine drug screen if available
• PITC

Treatment

Aim of treatment is to reduce/ remove symptoms and to encourage abstinence from the psycho-active drug

Primary treatment

• Advise to stop using the drug
• A short course of oral Diazepam may help with agitation, insomnia while symptoms resolve Prescribe Chlorpromazine 100mg nocte or Haloperidol 2.5mg nocte and increase weekly/two weekly depending on response and side effects. Continue treatment for up to six months after resolution of symptoms.
• In Substance induced psychosis, psychotic symptoms should resolve in a month after cessation of substance. If symptoms persist beyond a month, a diagnosis of Schizophrenia should be considered and the patient managed as per the Schizophrenia guidelines.

Treatment duration:

• Medication should be continued for 6 months after complete symptom resolution
• When considering stopping medication, discuss carefully with the patient and guardian and start to reduce slowly over 2-4 weeks
• Advise about symptoms that would indicate relapse e.g difficulty sleeping, auditory hallucination, suspicious thoughts and inform to return to the clinic promptly
• Continue to monitor until medication free for 4- 6 weeks before discharging
• Advise them to return to the clinic for review if have any concerns in the future

Follow-up

• Psychosocial interventions for cessation of substance use should be used as described in Alcohol Related Disorders