Synopsis
Deliver integrated, non-exclusionary care when severe mental illness and substance use coexist, with a shared longitudinal formulation, proportional testing, coordinated treatment sequencing and practical harm reduction that protects life even before abstinence is achieved.
- Ask everyone with known or suspected psychosis about prescribed and non-prescribed drugs and alcohol, including substance, amount, frequency, pattern, route and duration; assess substance users for psychosis as well.
- Do not exclude a person from mental-health care because of substance use or from substance treatment because of psychosis; ongoing use is a clinical need, not a discharge criterion.
- Construct a timeline across intoxication, withdrawal, sleep loss, abstinence, mood and psychosis; substance-induced and independent illness can coexist and the formulation may change.
- Assess overdose, withdrawal, blood-borne viruses, medication interaction, self-harm, suicide, neglect, violence, exploitation, injury, housing and safeguarding at every meaningful change.
- Biological testing can help an agreed clinical question but NICE advises against routine screening tests without consent and an explicit care-plan purpose.
- For most adults with psychosis and substance misuse, secondary mental-health services retain care coordination while working jointly with specialist substance services when dependence or complexity warrants it.
- Tailor treatment sequence to the relative severity of both conditions, social context and readiness; use standard evidence-based treatment for psychosis because no antipsychotic has special superiority for coexisting substance misuse.
- Harm reduction includes naloxone, sterile equipment, hepatitis and HIV testing and treatment, safer-sex care, avoiding sedative combinations and solitary use, dose reduction after abstinence, thiamine and continuity of opioid substitution.
Key red flags
Respiratory depression, reduced consciousness, seizure, delirium, hyperthermia, chest pain or severe autonomic disturbance requires urgent medical treatment before diagnostic debate.
A specific suicide plan, command hallucinations, severe mania, rapidly escalating violence or inability to meet basic needs requires crisis intervention alongside substance care.
Alcohol or benzodiazepine dependence with sudden reduction carries seizure and delirium risk; opioid abstinence or missed substitution treatment raises overdose risk on return.
Homelessness, coercion, sexual exploitation, domestic abuse, dependent children or cognitive impairment requires an explicit safeguarding and practical response.
Planned detoxification in a person with psychosis should involve specialist substance services and usually occur in an appropriate inpatient setting as part of the overall care plan.
Investigation priorities
Map mental symptoms, each substance, medicines, sleep, risk and functioning across exposure and lower-use periods.
Management branches
Intoxication, overdose or withdrawal coincides with psychosis, severe mood symptoms or immediate risk.
- Stabilise ABC, glucose, temperature and injury and treat the observed toxidrome or withdrawal without waiting for diagnostic certainty.
- Assess suicide, violence, self-neglect, capacity, exploitation and dependants, involving crisis and safeguarding services immediately where needed.
- Document a provisional integrated formulation and arrange direct transfer to teams responsible for both continuing mental-health and substance treatment.