Schizophrenia and Related Psychotic Disorders

Psychotic disorders — schizophrenia and the related conditions on its spectrum — are brain disorders that distort or interrupt a person's contact with reality, affecting thought, perception, emotion, and behaviour. Symptoms cluster into four domains that must each be assessed and treated: positive symptoms (delusions, hallucinations, disorganized thinking, speech, and behaviour), negative symptoms (social withdrawal, apathy, anhedonia, and emotional blunting), cognitive symptoms (impaired attention, concentration, and memory), and mood symptoms (dysphoria, anxiety, and emotional lability).^[1] Onset is typically in late adolescence or early adulthood, and a longer duration of untreated psychosis before treatment starts is associated with worse short- and long-term outcomes — this is why early detection and rapid referral to a specialized early psychosis program, where available, is a central emphasis of current Canadian practice.^[2] Antipsychotic medications are the cornerstone of treatment across every phase of illness, but are only fully effective when integrated with psychosocial interventions and ongoing physical health monitoring, since antipsychotics carry a substantial metabolic, cardiovascular, and movement-disorder burden that pharmacists are well positioned to catch early. A patient whose illness does not respond to two adequate trials of a non-clozapine antipsychotic has treatment-resistant schizophrenia and should be offered clozapine, the only antipsychotic with proven efficacy in that setting.^[3]

Prodromal symptoms (clinical high risk)

No single symptom is diagnostic, but the following pattern — especially when it represents a clear change from the person's baseline — should prompt assessment for clinical high-risk/prodromal psychosis: reduced concentration and attention; reduced drive, motivation, and energy; depressed mood; sleep disturbance; anxiety; social withdrawal; deterioration in day-to-day functioning; and irritability.^[2] Structured tools (e.g., the Structured Interview for Prodromal Syndromes, the Scale of Prodromal Symptoms) can support this assessment where available.

First-episode psychosis

In addition to the prodromal pattern above, features suggesting an evolving first psychotic episode include: rapid mood fluctuation (emotional lability) or markedly reduced facial expression; unreasonable suspiciousness; insomnia, restlessness, and pacing at night; unusual or bizarre behaviour; unusual perceptual experiences (hypersensitivity, illusions, brief intermittent hallucinations); and new difficulty organizing or expressing thoughts.^[1]

Substance use — particularly cannabis — is common around the time of a first psychotic episode and can make the diagnosis harder to pin down; a substance-induced psychosis can be misdiagnosed when the true picture is an emerging primary psychotic disorder that a substance has unmasked or precipitated. Suspect a primary (functional) psychosis rather than a purely substance-induced one when symptoms precede the onset of substance use, are bizarre or accompanied by marked thought disorder, or persist well beyond the expected period of intoxication or withdrawal.

• Family history of a psychotic disorder.
• Childhood trauma.
• Obstetric complications, including extreme prematurity and hypoxia/ischemia at birth.
• Cannabis use, particularly heavier and higher-potency use, which can trigger onset in a genetically vulnerable individual.
• Prenatal/perinatal factors: maternal malnutrition, maternal viral illness (e.g., influenza), maternal obesity, prenatal x-ray radiation exposure, prenatal exposure to Toxoplasma gondii (cat feces), certain analgesic exposure (e.g., ASA) in pregnancy, season of birth (proposed link to reduced sunlight/vitamin D exposure), maternal-fetal Rh incompatibility, and low birth weight.
• Comorbid substance use disorder more broadly — associated with poorer treatment adherence and outcomes once illness is established.

Differentiating psychotic disorders on presentation

Because symptoms can evolve during the early phase of illness, treat the initial diagnosis as provisional and re-evaluate as the clinical picture unfolds — many first presentations are reclassified once the required duration criteria are, or are not, ultimately met.^[1]

History

• A thorough history of the presenting problem, with attention to the onset and course of prodromal symptoms and the onset, character, and severity of psychotic symptoms.
• Changes in behaviour and day-to-day functioning.
• History of suicidal ideation or behaviour, and of aggressive or violent ideation or behaviour.
• Substance use in relation to the onset and course of psychotic symptoms.
• Collateral information from family or other sources whenever possible — people with psychotic disorders are often poor historians, and interviewing family with the patient's consent (or accepting unsolicited collateral information without disclosing confidential details back) adds essential information.
• Assess capacity to consent to treatment in every acutely psychotic patient; if capacity is lacking, a substitute decision-maker (usually a family member) must be involved as required by provincial legislation.

Rating scales and functional assessment

Use validated tools at baseline and at intervals to track symptomatic and functional recovery: the Clinical Global Impression Scales for Severity (CGI-S) and Change (CGI-C), and the Social and Occupational Functioning Assessment Scale (SOFAS), are simple enough for routine use; the Brief Psychiatric Rating Scale (BPRS) and Positive and Negative Syndrome Scale (PANSS) require specific training to use reliably. The Calgary Depression Scale for Schizophrenia (CDSS) is validated specifically to distinguish a genuine major depressive episode from negative symptoms or antipsychotic-induced emotional blunting in this population — a score of 6 or higher is clinically significant and warrants specific treatment for depression rather than simply adjusting the antipsychotic.^[1]

Baseline and targeted investigations

Routine neuroimaging and genetic testing are not required for a typical-age first episode with a normal neurological examination — reserve them for atypical presentations.^[1]

• Prevent progression to psychosis in patients at clinical high risk.
• Reduce psychotic agitation during acute episodes.
• Achieve remission of positive, negative, cognitive, and mood symptoms — not positive symptoms alone.
• Reduce the risk of psychiatric comorbidity, particularly suicide and depression.
• Reduce the risk of physical comorbidity, including metabolic syndrome and cardiovascular disease.
• Reduce substance use.
• Reduce the risk of harm to self or others.
• Reduce social isolation from family, friends, and community supports.
• Facilitate recovery of functioning and healthy development.
• Prevent or minimize recurrence of psychotic episodes.

• Choose the least restrictive treatment setting possible while ensuring safety; acutely agitated patients at imminent risk of harm to self or others require hospitalization, involuntarily if necessary, under the applicable provincial mental health legislation.
• See outpatients at least weekly for the first 4-6 weeks after an acute episode to build rapport, provide psychoeducation and practical support, promote adherence, and monitor both response and adverse effects.
• Foster a collaborative relationship between the patient, family/caregivers, and the treatment team, and maintain continuity of care with the same clinician or team whenever possible.
• Provide individual and family psychoeducation, cognitive behavioural therapy (CBT — also effective for residual psychotic symptoms and for comorbid depression/anxiety), motivational interviewing, social and vocational skills training, supported employment programs, and peer support groups; these improve functional outcome and adherence and help prevent relapse.
• Refer patients with serious, ongoing illness, significant functional disability, or comorbid substance use to an Assertive Community Treatment (ACT) team where available.
• Provide dietary and exercise counselling to help prevent and manage antipsychotic-associated weight gain and metabolic side effects; structured exercise and tai chi may also improve psychiatric symptoms and motor coordination.
• Actively encourage smoking cessation at every visit — smoking is disproportionately common in this population and is a major contributor to the markedly increased cardiovascular risk pharmacists should be watching for. Nicotine replacement therapy, bupropion, and varenicline are all appropriate options; monitor for mood or behavioural changes when starting varenicline or bupropion, particularly in patients with a history of suicidal ideation, depressed mood, or agitation/hostility.
• Use a harm-reduction approach incorporating motivational interviewing for comorbid substance use, and refer patients with persistent substance use to an integrated mental health/addiction program.

All FGAs and SGAs except clozapine have broadly similar efficacy against positive symptoms — the choice between them is driven by tolerability and adverse-effect profile, not by an expectation of superior symptom control.^[3]

Pregnancy

Screen every patient with a psychotic disorder for pregnancy risk and provide contraception/pregnancy counselling early in the illness course — if pregnancy is planned, arrange psychiatrist consultation to weigh the risks and benefits of maintenance antipsychotic therapy before conception where possible. A first psychotic episode occurring during pregnancy is a psychiatric emergency: psychosis in pregnancy is associated with worse obstetric and neonatal outcomes, and untreated psychosis carries real risk to both patient and fetus, so treat with the same urgency as in a non-pregnant patient. No randomized trial data exist for antipsychotics in pregnancy, and major congenital malformations have not been demonstrated with antipsychotic use, though gestational diabetes risk may be increased, particularly with agents carrying the highest metabolic burden (olanzapine, quetiapine).^[1] For most pregnant patients on maintenance antipsychotic therapy, continuing at the lowest effective dose is recommended over stopping, since an acute relapse itself carries real risk to the pregnancy and may ultimately expose the fetus to higher medication doses used to treat a breakthrough episode. Manage every pregnancy in a patient with schizophrenia as high-risk, with combined obstetric and mental-health follow-up.^[1]

Postpartum period

Relapse risk is high in the postpartum period, especially in the first 3 months after delivery, and higher still after a prior episode of postpartum psychosis — restart antipsychotic therapy immediately after delivery if it was stopped during pregnancy, and monitor patients on low-dose maintenance therapy closely for early signs of relapse, since the postpartum dose requirement may be higher than the pregnancy dose. Postpartum psychosis is a psychiatric emergency because of the risk of suicide and infanticide; if hospitalization is required and it is safe to do so, keep the patient and infant together, ideally in a specialized unit. For an infant exposed to clozapine in utero, obtain a neutrophil count; for an infant exposed to a high-potency FGA in the third trimester, monitor for extrapyramidal symptoms for the first several days of life.^[1]

Breastfeeding

Antipsychotics pass into breast milk at levels generally considered compatible with breastfeeding, though long-term infant outcome data remain limited — discuss the individual risk/benefit balance with each patient. Among the SGAs, olanzapine has the most reassuring breastfeeding data (the largest number of documented cases with low infant exposure), and quetiapine also shows low infant exposure; risperidone is associated with greater infant exposure and is not preferred if an alternative is suitable. Breastfeeding is not recommended while taking clozapine. If any antipsychotic is used during breastfeeding, monitor the infant for poor feeding, lethargy, excess drowsiness, and delayed developmental milestones.^[1]

Older adults

Antipsychotics carry an increased risk of cerebrovascular events and death when used specifically for dementia-related behavioural symptoms — reserve them for that indication only when non-pharmacologic measures have failed and the risk/benefit has been explicitly discussed. In older adults generally, start at a lower dose, titrate more slowly, and monitor more closely for orthostatic hypotension, sedation, falls, and anticholinergic burden; low-potency FGAs and the most anticholinergic SGAs (clozapine, olanzapine, quetiapine) warrant particular caution.

Children and youth

First-episode patients of any age are more responsive to lower antipsychotic doses and more prone to side effects than multi-episode adults — start low and titrate gradually. Pediatric- and youth-specific dosing, monitoring, and psychosocial program considerations are covered by a dedicated Canadian pediatric schizophrenia guideline; involve a psychiatrist experienced in pediatric psychosis for any patient under 18.

Renal and hepatic impairment

Most antipsychotics are primarily hepatically metabolized; use caution and consider lower starting doses in significant hepatic impairment. Paliperidone is minimally hepatically metabolized (an advantage in hepatic impairment) but requires dose adjustment in renal impairment — consult product-specific dosing for renal impairment for any antipsychotic in a patient with reduced kidney function.

Routine monitoring schedule

The following schedule applies across the first-episode, recurrent-episode, stabilization, and stable phases of illness.^[1]

Clozapine-specific hematological monitoring

Clozapine carries a real risk of agranulocytosis and requires mandatory, dedicated absolute neutrophil count (ANC) monitoring for the entire duration of therapy through the Clozapine Support and Assistance Network (CSAN) program in Canada — a prescription cannot be dispensed without a current, in-range result.^[4]

A 2025 international consensus (global Delphi panel) has proposed simplifying this schedule — moving to monthly monitoring after 18 weeks and discontinuing routine ANC monitoring altogether after 2 years of treatment, alongside a lower ANC threshold for considering permanent discontinuation. This has not yet been adopted into the mandatory Canadian CSAN monitoring requirement described above, so continue following the CSAN schedule for now — but expect Canadian practice to move toward less intensive long-term monitoring as this evidence is incorporated.^[5]

Ask about, and document, smoking status at every clozapine or olanzapine visit — smoking induces the CYP1A2 enzyme that metabolizes both drugs, so a patient who quits smoking (including during a smoke-free hospital admission) needs a dose reduction to avoid toxicity, and a patient who resumes smoking needs the dose reassessed upward; this interaction comes from combustion byproducts, not nicotine itself, so nicotine replacement therapy does not require the same dose adjustment.^[3]

1. Confirm adherence and screen for ongoing substance use before concluding the antipsychotic has failed — both are common, correctable causes of apparent treatment failure.
2. Confirm the trial was adequate: at least 4-6 weeks at a dose within the therapeutic range. Reassess a partial responder again at 8 weeks before switching; a patient with no response at all by 4 weeks is unlikely to benefit from continuing longer at that dose.
3. If a single adequate trial has failed, switch to a different antipsychotic using a gradual cross-titration (2 weeks to 3 months) rather than an abrupt switch, to avoid unnecessary polypharmacy and withdrawal-related symptoms; a Canadian online tool (SwitchRx) can guide the crossover schedule.
4. If 2 or more adequate trials (each at least 6 weeks) of different non-clozapine antipsychotics have failed to produce a meaningful reduction in positive symptoms, this is treatment-resistant schizophrenia — start clozapine.^[3]
5. If clozapine produces only a partial response despite an adequate dose and, where available, a therapeutic plasma level, consider adding a second antipsychotic as an adjunct under psychiatrist direction — this is one of only 2 evidence-supported antipsychotic polypharmacy scenarios. Do not switch a stabilized clozapine responder to a different antipsychotic.
6. If extrapyramidal symptoms or tardive dyskinesia are limiting therapy on an FGA, switch to an SGA; for persistent, severe tardive dyskinesia despite switching, consider a clozapine trial (clozapine carries the lowest EPS/TD risk of any antipsychotic) or a psychiatrist-directed trial of clonazepam or tetrabenazine, both of which have limited but real supporting evidence in this setting.^[6]
7. If postpsychotic depression or persistent suicidality is present despite antipsychotic treatment, add an antidepressant in the stabilization or stable phase (evidence does not support starting an antidepressant in the acute phase), and give specific consideration to a clozapine trial when suicidality is persistent.

• Combining parenteral olanzapine with a parenteral benzodiazepine — this combination has caused severe sedation and cardiorespiratory depression, including death.
• Using zuclopenthixol acetate (short-acting depot) in an antipsychotic-naive patient — reserve it for antipsychotic-experienced patients with severe acute agitation.
• Assuming rapid dose escalation or very high doses produce a faster or better response — for most patients this is not true and simply adds side effects; the main exceptions needing rapid titration are ziprasidone and extended-release quetiapine.
• Using anticholinergic medication prophylactically, or using it to treat tardive dyskinesia — anticholinergics do not prevent EPS reliably enough to justify routine use, are not effective for tardive dyskinesia, and can make tardive dyskinesia worse.
• Reducing the antipsychotic dose below the effective acute-phase dose in a stable, multi-episode patient — this raises relapse risk without benefit.
• Treating only positive symptoms and overlooking negative, cognitive, and mood symptoms, which drive much of the long-term functional disability in this illness.
• Stopping antipsychotic therapy during pregnancy without a specific discussion of the relapse risk this creates, or failing to restart it promptly after delivery — the postpartum period carries a particularly high relapse risk.
• Missing a needed clozapine or olanzapine dose adjustment when a patient's smoking status changes (starting, stopping, or restarting) — this is a CYP1A2 induction effect from smoke, not nicotine, so nicotine replacement therapy does not trigger the same adjustment.
• Treating long-acting injectable antipsychotics as a last-resort option for repeatedly nonadherent patients rather than offering them proactively in any phase, including the first episode.
• Missing a baseline prolactin, fasting glucose, or lipid panel before starting an antipsychotic, which removes the ability to tell whether a later abnormal value is treatment-related.
• Missing the mandatory ANC check before dispensing a clozapine prescription, or missing the twice-weekly monitoring escalation required for a yellow-alert result.

How to use this table: Doses are adult doses and require patient-specific confirmation, including renal/hepatic adjustment. All antipsychotics carry a common counselling point: advise patients about antipsychotic-associated body temperature dysregulation and heat-stroke prevention (hydration, sun protection). Select any drug name to open its complete Pharmasist Drug Database page.

First-generation antipsychotics — low potency

Greater sedation, cardiovascular effects, anticholinergic effects, and weight gain than higher-potency FGAs.

First-generation antipsychotics — intermediate potency

The preferred FGA subgroup when an FGA is used, given a lower EPS burden than high-potency agents.

First-generation antipsychotics — high potency

Greater risk of EPS, neuroleptic malignant syndrome, and hyperprolactinemia than lower-potency FGAs.

Second-generation antipsychotics

Preferred first-line class given more favourable tolerability overall; clozapine is reserved for treatment-resistant disease. See Special Populations and Monitoring & Follow-up for pregnancy/breastfeeding and metabolic monitoring detail.

Antipsychotic-induced movement disorder management

Prevention (favouring an SGA first-line) is the primary strategy — none of these agents reliably treats tardive dyskinesia, and anticholinergics can worsen it.

Acute agitation adjuncts

Given alongside, not instead of, an antipsychotic for acute psychotic agitation.

Metabolic monitoring adjunct and smoking cessation

Address the substantial metabolic and cardiovascular burden of antipsychotic therapy directly — see the Tobacco Use Disorder chapter for full smoking-cessation dosing detail.

Mood-related adjuncts (schizoaffective disorder or specialist-directed augmentation)

Used for the mood component of schizoaffective disorder, or as specialist-directed augmentation in specific circumstances — not routine antipsychotic-alone therapy.

Evidence note: Drug inventory, dosing, adverse effects, and comments reflect standard Canadian practice, cross-checked against the current Canadian schizophrenia pharmacotherapy guideline and the 2021 American Psychiatric Association practice guideline.^[3][7]