Prescription medication · Atypical Antipsychotic
clozapine
Also sold as Clozaril. Versacloz is used to treat schizophrenia in people who haven't responded well to other antipsychotic medicines.
Data updated 2026-05-15
- 121,298
- FDA reportsOften reported
- 42
- InteractionsMany interactions
- 96% less
- Generic vs brandHuge savings
- $15.68
- Brand price (NADAC)
What the data shows
clozapine (Clozaril) is a prescription Atypical Antipsychotic, more reported than most tracked drugs (121,298 FDA reports), whose generic costs a fraction of the brand (about 96% less).
Reporting volume reflects how widely a drug is used and studied, not how dangerous it is, a FAERS report documents a temporal association, never proof of cause.
clozapine (Clozaril) is a prescription Atypical Antipsychotic. Versacloz is used to treat schizophrenia in people who haven't responded well to other antipsychotic medicines.
Versacloz is a medicine used to treat severe schizophrenia when other medicines have not worked. It can also help lower the risk of suicidal behavior in people with schizophrenia or schizoaffective disorder.
Verify with FDA → · CMS NADAC pricing →
Drug Pricing (NADAC)
Brand Price
$15.68/unit
Generic Price
$0.56/unit
Generic Savings
96%
Generic Available
Yes (6 manufacturers)
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
Versacloz is used to treat schizophrenia in people who haven't responded well to other antipsychotic medicines.
Common side effects
Feeling sleepy, Dizziness, Headache
Key warnings
Versacloz can cause several serious side effects: * **Severe Neutropenia:** This means a dangerously low white blood cell count, which increases your risk of infection.
The sections below are summarized in plain English from clozapine's FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.
How It Works
Versacloz works by affecting certain chemicals in the brain. These chemicals, like dopamine and serotonin, are involved in mood, behavior, and thinking. By changing the levels of these chemicals, Versacloz can help reduce symptoms of schizophrenia and lower the risk of suicidal behavior.
How to Take It
Start with 12.5 mg once or twice a day. Your doctor may slowly increase the dose by 25 mg to 50 mg each day. The goal is to reach 150 mg to 225 mg twice a day within two weeks. The maximum dose is 450 mg twice a day. You can take Versacloz with or without food.
This is a plain-language summary of clozapine's FDA labeling, not individualized dosing advice. Ask a pharmacist or prescriber before changing how you take this medication.
Pregnancy & Breastfeeding
Tell your doctor if you are pregnant or plan to become pregnant. Babies born to mothers who take Versacloz in the third trimester may have withdrawal symptoms or other problems after birth. There is a pregnancy registry for women who take atypical antipsychotics like Versacloz.
This is a plain-language summary of clozapine's FDA labeling, not individualized advice. Ask a pharmacist or prescriber about pregnancy or breastfeeding on this medication.
Missed Dose
If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule.
This is a plain-language summary of clozapine's FDA labeling, not individualized advice. Ask a pharmacist or prescriber what to do about your specific missed dose.
Storage
Store Versacloz at room temperature, away from light, and do not refrigerate or freeze. Shake well for 10 seconds before use. Throw away any remaining medicine 100 days after opening the bottle.
Side Effects (from patient reports)
Based on 121,298 FDA adverse event reports.
Most-reported reactions
Adverse reactions in FAERS for clozapine, by number of reports
- Low white blood cell count
Low white blood cell count
18,655 reports
- Needing to stay in the hospital
Needing to stay in the hospital
12,101 reports
- Death
Death
11,398 reports
- A mental disorder that affects how a person thinks, feels, and behaves 4,547
A mental disorder that affects how a person thinks, feels, and behaves
4,547 reports
- High white blood cell count 4,446
High white blood cell count
4,446 reports
- Low white blood cell count 4,370
Low white blood cell count
4,370 reports
- High neutrophil count 4,115
High neutrophil count
4,115 reports
- Feeling unwell 3,704
Feeling unwell
3,704 reports
- Lung infection 3,189
Lung infection
3,189 reports
- Not following the treatment plan 3,093
Not following the treatment plan
3,093 reports
What this shows Bars show how often each reaction was reported, not how likely it is to happen, a report records a temporal association, never proof that the drug caused it.
Reports over time
Adverse-event reports filed for clozapine each year to the FDA Adverse Event Reporting System (FAERS).
Year-to-year volume tracks usage, prescribing, and scrutiny, not a change in per-patient risk. Source: FDA FAERS.
Where clozapine sits
clozapine has more FDA adverse-event reports than 88% of the drugs FAERS tracks. A high position reflects how widely a drug is used and watched, not how dangerous it is.
Percentile across all drugs PlainMeds tracks by FAERS report volume. The dot is clozapine; the line is the median (50th percentile).
FDA Adverse Event Report Analysis
Detailed analysis of 121,298 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 2001–2025.
Total Reports
121,298
Reports Mentioning Death
21,448
17.7% of reports — not proof of cause
Hospitalization Reports
53,005
Top Indication
Product Used For Unknown Indication
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 1 | NEUTROPENIA | 18,655 |
| 2 | HOSPITALISATION | 12,101 |
| 3 | DEATH | 11,398 |
| 4 | SCHIZOPHRENIA | 4,547 |
| 5 | WHITE BLOOD CELL COUNT INCREASED | 4,444 |
| 6 | WHITE BLOOD CELL COUNT DECREASED | 4,370 |
| 7 | NEUTROPHIL COUNT INCREASED | 4,114 |
| 9 | MALAISE | 3,706 |
| 11 | PNEUMONIA | 3,190 |
| 12 | TREATMENT NONCOMPLIANCE | 3,093 |
| 13 | NEUTROPHIL COUNT DECREASED | 3,088 |
| 14 | DRUG INTERACTION | 3,056 |
| 15 | PSYCHOTIC DISORDER | 3,037 |
| 16 | HAEMOGLOBIN DECREASED | 3,027 |
| 17 | TACHYCARDIA | 2,764 |
Reactions in Death Reports
Reactions in Hospitalization Reports
Source: FDA FAERS (Adverse Event Reporting System) FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation
Serious Warnings
Versacloz can cause several serious side effects: * **Severe Neutropenia:** This means a dangerously low white blood cell count, which increases your risk of infection. You will need regular blood tests to check your white blood cell count. * **Orthostatic Hypotension, Bradycardia, and Syncope:** This means low blood pressure when standing up, slow heart rate, and fainting. These are most likely when you first start taking Versacloz or when the dose is increased. * **Seizures:** Versacloz can increase your risk of seizures, especially at higher doses. * **Myocarditis, Pericarditis, and Cardiomyopathy:** These are serious heart problems that can be fatal. Tell your doctor right away if you have chest pain, shortness of breath, or other heart-related symptoms. * **Increased Mortality in Elderly Patients with Dementia-Related Psychosis:** Elderly patients with dementia who take antipsychotic medicines like Versacloz have an increased risk of death.
Known Drug Interactions
Anticholinergic Drugs Concomitant treatment with clozapine and other drugs with anticholinergic activity (e.g., benztropine, cyclobenzaprine, diphenhydramine) can increase the risk for anticholinergic toxicity and severe gastrointestinal adverse reactions related to hypomotility.
Mechanism: Both drugs have similar side effects that can slow down your digestive system and cause confusion or dry mouth. Combining them makes these side effects much more likely and can lead to severe constipation or toxicity.
What to do: Your doctor should monitor you for signs of toxicity or severe stomach issues. They may need to adjust your dose or choose a different medication to avoid these complications.
Anticholinergic Drugs Concomitant treatment with clozapine and other drugs with anticholinergic activity (e.g., benztropine, cyclobenzaprine, diphenhydramine) can increase the risk for anticholinergic toxicity and severe gastrointestinal adverse reactions related to hypomotility.
Mechanism: These two drugs both block certain signals in the body, which can lead to a 'double dose' of side effects like extreme sleepiness and severe constipation. This happens because both medications have similar drying and slowing effects on the body.
What to do: Be careful when using these together and watch for signs of severe constipation or confusion. Consult your healthcare provider before taking over-the-counter allergy or sleep aids while on clozapine.
Monoamine Oxidase Inhibitors (MAOIs): ( 2.9 , 2.10 , 4.1 , 5.2 ) Drugs Metabolized by CYP2D6: Fluoxetine is a potent inhibitor of CYP2D6 enzyme pathway ( 7.7 ) Tricyclic Antidepressants (TCAs): Monitor TCA levels during coadministration with fluoxetine or when fluoxetine has been recently discontinued ( 5.2 , 7.7 ) CNS Acting Drugs: Caution should be used when taken in combination with other centrally acting drugs ( 7.2 ) Benzodiazepines: Diazepam – increased t½, alprazolam - further psychomotor performance decrement due to increased levels ( 7.7 ) Antipsychotics: Potential for elevation...
Mechanism: Fluoxetine prevents your body from processing clozapine correctly, leading to higher levels of the drug. This increases the risk of experiencing dangerous side effects.
What to do: Your doctor should monitor your blood levels and watch you closely for side effects. They may need to adjust your clozapine dose.
CYP2D6 and CYP3A4 Inhibitors Concomitant treatment with VERSACLOZ and CYP2D6 or CYP3A4 inhibitors (e.g., cimetidine, escitalopram, erythromycin, paroxetine, bupropion, fluoxetine, quinidine, duloxetine, terbinafine, or sertraline) can increase clozapine levels and lead to adverse reactions [see Clinical Pharmacology (12.3) ] .
Mechanism: Sertraline interferes with the way your body gets rid of clozapine. This can cause clozapine to reach high levels in your blood and increase the risk of side effects.
What to do: Your doctor should monitor you closely for side effects and may need to lower your clozapine dose.
CYP2D6 and CYP3A4 Inhibitors Concomitant treatment with VERSACLOZ and CYP2D6 or CYP3A4 inhibitors (e.g., cimetidine, escitalopram, erythromycin, paroxetine, bupropion, fluoxetine, quinidine, duloxetine, terbinafine, or sertraline) can increase clozapine levels and lead to adverse reactions [see Clinical Pharmacology (12.3) ] .
Mechanism: Escitalopram slows down the process of clearing clozapine from your body. This leads to higher amounts of clozapine in your system than intended.
What to do: Watch for increased side effects like extreme sleepiness or dizziness, and talk to your doctor about whether your clozapine dose needs to be changed.
This is a plain-language summary of interactions documented in FDA labeling, not individualized advice. Ask a pharmacist or prescriber before combining medications.
Common Questions
What should I do if I feel dizzy when standing up?
Can I drink alcohol while taking Versacloz?
How often will I need blood tests?
What are the symptoms of a low white blood cell count?
Can I take other medicines with Versacloz?
What should I do if I get constipated?
Can Versacloz cause weight gain?
Will Versacloz make me sleepy?
How long does it take for Versacloz to start working?
What happens if I stop taking Versacloz suddenly?
What are the common side effects of clozapine?
Does clozapine interact with other medications?
What drug class is clozapine?
Is there a generic version of clozapine?
Is clozapine safe during pregnancy?
Related Medications in Atypical Antipsychotic
Other drugs grouped near clozapine - same-class peers and common alternatives.
acamprosate
Campral
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alprazolam
Xanax
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amitriptyline
Elavil
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amphetamine/dextroamphetamine
Adderall, Adderall XR
Adderall XR is a stimulant medicine.
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aripiprazole
Abilify
Aripiprazole (Abilify) is a medicine used to treat certain mental disorders and mood problems.
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Medication Guides
Understanding Drug Interactions
How CYP450 enzymes, inhibitors, and inducers affect your medications
Generic vs Brand Name Drugs
FDA requirements, cost savings, and when the difference matters
Narrow Therapeutic Index Drugs
Why some drugs demand precise dosing and monitoring
Common Drug Interactions
Dangerous medication combinations and how to protect yourself
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What the FDA Data Shows for clozapine
The FDA label for clozapine (sold under brand names such as Clozaril) classifies it as a prescription-only medication in the Atypical Antipsychotic class. Versacloz is used to treat schizophrenia in people who haven't responded well to other antipsychotic medicines. Official labeling lists 14 commonly reported side effects, including Feeling sleepy, Dizziness, Headache.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 121,298 voluntary reports. The database also lists 42 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated moderate severity. NADAC pricing from CMS shows a generic unit cost of $0.56 versus $15.68 for the brand - a 96% generic savings.
Report counts do not establish causation, a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history, and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice, always consult a licensed healthcare provider before starting, stopping, or changing any medication.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC).
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.
Last updated: June 23, 2025
Read our methodology - how this data is sourced, computed, and verified.
Data currency: FDA FAERS adverse-event reports through 2025, CMS NADAC acquisition-cost pricing effective December 2024, compiled and last refreshed May 2026. See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a correction.
All federal data sources used on this page
- FDA Orange Book - approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed - NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) - post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm - standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files - federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database - current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages