Substance Induced Psychotic Disorder

Substance or medication induced psychotic disorder is prominent hallucinations or delusions occurring during or soon after intoxication or withdrawal, or after medication exposure, in excess of expected effects.

• Substances: cannabis (especially high potency), amphetamines, methamphetamine, cocaine, hallucinogens, ketamine, synthetic cannabinoids, alcohol (withdrawal, hallucinosis), steroids, levodopa, anticholinergics.
• Resolves usually within 1 month of abstinence; persistent psychosis suggests primary disorder (about 25 to 50% convert to schizophrenia, highest with cannabis, amphetamines).
• Risk of violence and suicide.

• Paranoia, hallucinations (auditory, visual, tactile in stimulant), agitation, disorganised behaviour, insomnia.
• Autonomic features of intoxication or withdrawal; delirium in alcohol withdrawal.
• Rapid onset after substance use.

• Temporal relationship with substance use; urine toxicology (note synthetic cannabinoids missed).
• Exclude primary psychosis (history of psychosis before use or persisting over 1 month after abstinence), delirium, epilepsy, infection, metabolic disease, head injury.
• Physical examination, glucose, electrolytes, ECG, CT head if head trauma.
• Assess dependence and risk.

• Remove the agent, supportive care in a calm environment, hydration.
• Agitation: lorazepam 1 to 2 mg PO/IM or diazepam 5 to 10 mg; antipsychotic if psychosis persists (olanzapine 5 to 10 mg, haloperidol 2 to 5 mg with caution in stimulant intoxication due to cardiovascular risk and seizures).
• Alcohol withdrawal: chlordiazepoxide or diazepam taper, thiamine 100 mg.
• Short term antipsychotic (2 to 4 weeks) then withdraw if resolved; long term if persists beyond 1 month.
• Addiction treatment: motivational interviewing, CBT, contingency management (stimulants), residential rehabilitation.
• Long term follow up for conversion to primary psychosis.