Episodes of substance-induced psychosis are common in emergency departments and crisis centers. There are many precipitating substances, including alcohol Alcohol Toxicity and Withdrawal Alcohol (ethanol) is a central nervous system depressant. Large amounts consumed rapidly can cause respiratory depression, coma, and death. Large amounts chronically consumed damage the liver... read more , amphetamines Amphetamines Amphetamines are sympathomimetic drugs with central nervous system stimulant and euphoriant properties whose toxic adverse effects include delirium, hypertension, seizures, and hyperthermia... read more , cannabis Marijuana (Cannabis) Marijuana is a euphoriant that can cause sedation or dysphoria in some users. Psychologic dependence can develop with chronic use, but very little physical dependence is clinically apparent... read more , cocaine Cocaine Cocaine is a sympathomimetic drug with central nervous system stimulant and euphoriant properties. High doses can cause panic, schizophrenic-like symptoms, seizures, hyperthermia, hypertension... read more , hallucinogens Hallucinogens Hallucinogens are a diverse group of drugs that can cause highly unpredictable, idiosyncratic reactions. Intoxication typically causes hallucinations, with altered perception, impaired judgment... read more , opioids Opioid Toxicity and Withdrawal Opioids are euphoriants that, in high doses, cause sedation and respiratory depression. Respiratory depression can be managed with specific antidotes (eg, naloxone) or with endotracheal intubation... read more , phencyclidine Ketamine and Phencyclidine (PCP) Ketamine and phencyclidine are dissociative anesthetics that can cause intoxication, sometimes with confusion or a catatonic state. Overdose can cause coma and, rarely, death. Ketamine and phencyclidine... read more (PCP), and sedative/hypnotics Anxiolytics and Sedatives Anxiolytics and sedatives include benzodiazepines, barbiturates, and related drugs. High doses can cause stupor and respiratory depression, which is managed with intubation and mechanical ventilation... read more . To be considered substance-induced psychosis, the hallucinations and delusions should be in excess of those that typically accompany simple substance intoxication or withdrawal, although the patient may also be intoxicated or withdrawing.
Symptoms are often brief, resolving shortly after the causative drug is cleared, but psychosis triggered by amphetamines, cocaine, or PCP may persist for many weeks. Because some young people with prodromal or early-stage schizophrenia use substances that can induce psychosis, it is important to obtain a thorough history, particularly to seek evidence of prior mental symptoms before concluding that acute psychosis is due to substance use.
(See also Introduction to Schizophrenia and Related Disorders Introduction to Schizophrenia and Related Disorders Schizophrenia and related psychotic disorders—brief psychotic disorder, delusional disorder, schizoaffective disorder, schizophreniform disorder, and schizotypal personality disorder—are characterized... read more .)
In most substance-induced psychoses, stopping the substance and giving an anxiolytic (eg, a benzodiazepine) or antipsychotic drug Antipsychotic Drugs Antipsychotic drugs are divided into conventional antipsychotics and 2nd-generation antipsychotics (SGAs) based on their specific neurotransmitter receptor affinity and activity. SGAs may offer... read more is effective.
For psychosis due to dopamine-stimulating drugs such as amphetamine, an antipsychotic drug is most effective.
For psychosis due to drugs such as lysergic acid diethylamide (LSD), quiet observation may be all that is needed.
For substances with actions that do not involve dopamine, observation may be all that is needed, or an anxiolytic may help.