What is the algorithm for managing acute psychosis?

Algorithm for Acute Psychosis Management

Initiate antipsychotic treatment immediately if psychotic symptoms have persisted for ≥1 week with distress or functional impairment, or earlier if severe distress or safety concerns exist 1.

Initial Assessment & Treatment Timing

Before starting antipsychotics, rapidly assess whether symptoms are:

• Substance-induced: Delay treatment if clearly related to substance use and no safety concerns present 1. Cannabis or methamphetamine psychosis typically resolves within 30 days of abstinence 2.
• Medical causes: Rule out CNS infection, traumatic brain injury, dementia, or other organic illness 1, 2
• Primary psychotic disorder: Proceed with antipsychotic treatment

Critical timing: Do not wait if there are safety concerns to self or others, or severe distress—initiate treatment immediately 1.

First-Line Antipsychotic Selection

Use shared decision-making based on side-effect profiles 1. The choice depends on patient-specific factors:

Standard First-Line Options:

• Aripiprazole (D2 partial agonist): Preferred for females due to favorable prolactin and cardiometabolic profile 3
• Risperidone/Paliperidone
• Olanzapine (consider with samidorphan or concurrent metformin to prevent weight gain) 1

Avoid First-Line:

• First-generation antipsychotics (higher extrapyramidal symptoms risk)
• Amisulpride, risperidone, paliperidone, olanzapine, quetiapine in females when possible (prolactin elevation and cardiometabolic risks) 3

Dosing strategy: Start at the lowest licensed/effective dose and titrate upward 4. Give therapeutic dose for minimum 4 weeks with confirmed good adherence before declaring treatment failure 1.

Second-Line Treatment (After 4 Weeks)

If significant positive symptoms persist despite adequate trial:

Switch to alternative antipsychotic with different pharmacodynamic profile 1:

• If first-line was D2 partial agonist → switch to amisulpride, risperidone, paliperidone, or olanzapine (with metformin) 1
• Use gradual cross-titration based on half-life and receptor profiles 1
• Again trial for minimum 4 weeks at therapeutic dose with good adherence

Third-Line: Treatment-Resistant Psychosis

After failure of 2 adequate antipsychotic trials (each ≥4 weeks, therapeutic dose, good adherence):

1. Reassess diagnosis: Confirm schizophrenia, rule out organic illness, substance use 1
2. Initiate clozapine 1, 5—this is a Level 1B recommendation from APA guidelines 5

Clozapine Protocol:

• Start metformin concomitantly to prevent weight gain 1
• Titrate to achieve plasma level ≥350 ng/mL 1
• If inadequate response after 12 weeks at therapeutic level, increase to 350-550 ng/mL 1
• Concentrations >550 ng/mL have diminishing returns (NNT=17) and increased seizure risk—only use with patient/carer consultation and consider prophylactic lamotrigine 1

Clozapine Augmentation (if needed):

• Amisulpride, aripiprazole, or electroconvulsive therapy for persistent positive symptoms 1
• Antidepressant for persistent negative symptoms 1

Special Considerations

Acute Agitation:

• First-line: Lorazepam 6
• Second/third-line: Quetiapine or levomepromazine 6
• Taper and discontinue agitation medications after symptom remission 6

Poor Adherence:

Use long-acting injectable antipsychotic if history of poor adherence or patient preference 5—this is a Level 2B suggestion from APA.

Negative Symptoms:

Address secondary causes first:

• Persistent positive symptoms
• Depression
• Substance misuse
• Social isolation
• Medical illness (hypothyroidism)
• Antipsychotic side effects (extrapyramidal symptoms, sedation, weight gain causing sleep apnea) 1

Common Pitfalls

• Don't use polypharmacy: Single antipsychotic is superior to combining multiple agents 7
• Don't declare treatment failure prematurely: Must give full 4-week trial at therapeutic dose with confirmed adherence 1
• Don't delay clozapine: After 2 failed trials, clozapine should be initiated—it's the only evidence-based treatment for treatment-resistant schizophrenia 5, 4
• Don't ignore substance use: Cannabis and methamphetamine can cause psychosis that resolves with abstinence 2
• Exercise caution in elderly/dementia: Antipsychotics carry mortality risk in this population 2