Acute Psychosis

Key considerations: Substance-induced psychosis (stimulants, PCP, synthetic cannabinoids), Anti-NMDA receptor encephalitis, Delirium (medical cause masquerading as psychosis)

Cannot miss

Substance-induced psychosis (stimulants, PCP, synthetic cannabinoids)
Anti-NMDA receptor encephalitis
Delirium (medical cause masquerading as psychosis)
Thyroid storm
CNS infection (meningitis, encephalitis)
Acute intoxication/withdrawal

Likely diagnoses

Schizophrenia exacerbation
Schizoaffective disorder
Bipolar disorder with psychotic features
Brief psychotic disorder
Substance-induced

Red flags

First episode psychosis (needs full medical workup)
Age >40 with new-onset psychosis (think organic cause)
Abnormal vital signs
Focal neurological deficits
Fluctuating consciousness (delirium)
Catatonia

Workup

history: Psychiatric history, prior episodes; Medication adherence; Substance use (especially stimulants, cannabis, PCP); Timeline of symptom onset; Hallucinations: auditory vs visual (visual suggests organic); exam: Mental status exam; Neurological exam (focal deficits); Signs of substance use; Catatonia assessment (Bush-Francis); labs: CBC, BMP, glucose; TSH; Urine drug screen; Urinalysis; B12/folate if chronic; RPR/FTA-ABS (neurosyphilis); Anti-NMDA receptor Ab if young female with new psychosis; imaging: CT head if first episode or focal neuro signs; MRI brain if anti-NMDA or encephalitis suspected; bedside: Fingerstick glucose; Check temperature

Management

immediate: Ensure safety (patient and staff); De-escalation techniques first; Quiet, low-stimulation environment; general: Antipsychotic medication for acute psychosis; Avoid physical restraints when possible — use least restrictive measure; specific: diagnosis: Acute Agitation; steps: PO preferred: olanzapine 5-10mg or risperidone 2mg; IM if unable to take PO: olanzapine 10mg IM, or haloperidol 5mg + lorazepam 2mg IM + diphenhydramine 50mg IM (B52); Avoid combining IM olanzapine and IM benzodiazepine (respiratory depression risk); diagnosis: First-Episode Psychosis; steps: Full medical workup (labs, imaging); Start low-dose antipsychotic; Psychiatry consult; MRI brain, anti-NMDA Ab in young females; diagnosis: Catatonia; steps: Lorazepam 1-2mg IV challenge (diagnostic and therapeutic); If responsive: continue lorazepam; If refractory: consider ECT consult

Disposition

admit: All first-episode psychosis; Danger to self or others; Unable to care for self; Psychotic requiring inpatient stabilization; discharge: Known psychosis with mild exacerbation, medication adjustment, reliable outpatient follow-up; consults: Psychiatry for all cases; Neurology if anti-NMDA or encephalitis suspected

Clinical pearls

Visual hallucinations suggest organic/medical cause; auditory hallucinations more typical of primary psychosis
First episode psychosis in young women: test anti-NMDA receptor antibodies — treatable autoimmune encephalitis
B52: Benadryl 50mg + Haldol 5mg + Ativan 2mg IM — classic IM cocktail for severe agitation
Never combine IM olanzapine and IM benzodiazepine — risk of respiratory depression/arrest

Source and review

APA Practice Guidelines for Schizophrenia 2020. Last reviewed: 2024-11-01