clozapine
Brand names: Clozaril
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.
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.
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.
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.
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.
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 70,768 FDA adverse event reports.
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
Death-Related Reports
21,448
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 |
| 8 | DRUG INEFFECTIVE | 3,865 |
| 9 | MALAISE | 3,706 |
| 10 | OFF LABEL USE | 3,566 |
| 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 |
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 of...
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.
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?
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amitriptyline
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amphetamine/dextroamphetamine
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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 70,768 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.
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