cimetidine vs clozapine
PlainMeds reviewed this comparison against our methodology in August 2026. It places FDA and CMS record fields side by side, without recommending either medication.
Side-by-side comparison of cimetidine and clozapine. Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.
minor Known Drug Interaction
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) ] .
Tagamet
Clozaril
Cimetidine (Tagamet) reduces stomach acid. It is used to treat ulcers, heartburn, and other conditions where too much acid is produced.
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.
Cimetidine treats active duodenal ulcers for short periods. It can also be used long-term at a lower dose to prevent ulcers from returning. This medicine also treats active benign gastric ulcers for a short time. Additionally, it can help with erosive gastroesophageal reflux disease (GERD), which damages the esophagus.
Versacloz is used to treat schizophrenia in people who haven't responded well to other antipsychotic medicines. Schizophrenia is a mental illness that can cause hallucinations, delusions, and disorganized thinking. Versacloz can also help lower the risk of repeated suicidal behavior in people with schizophrenia or schizoaffective disorder who are at high risk.
Cimetidine is an H2 receptor antagonist. This means it blocks histamine from attaching to certain cells in your stomach. By blocking histamine, cimetidine reduces the amount of acid your stomach makes.
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.
- • Headache
- • Dizziness
- • Diarrhea
- • Feeling sleepy
- • Dizziness
- • Headache
- • Shaking
- • Fast heart rate
- Chronic Kidney Disease 1,264
- Acute Kidney Injury 710
- Renal Failure 694
- Nausea 681
- Fatigue 598
- Neutropenia 18,655
- Hospitalisation 12,101
- Death 11,398
- Schizophrenia 4,547
- White Blood Cell Count Increased 4,444
Reversible confusional states (like mental confusion, agitation, or hallucinations) have been reported, mostly in severely ill patients. These usually appear within 2-3 days of starting treatment and clear up within 3-4 days of stopping the drug.
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.
Tell your doctor if you are pregnant or plan to become pregnant. The effects of cimetidine during pregnancy are not fully known. Talk to your doctor about the risks and benefits of taking cimetidine while 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.
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How to Read This cimetidine vs clozapine Comparison
cimetidine is classified in the H2 Receptor Antagonist drug class, while clozapine sits within the Atypical Antipsychotic class. Drugs from different classes work through distinct mechanisms, so a head-to-head comparison illustrates trade-offs rather than equivalence. Both drugs are split between OTC and prescription status, which affects access and supervision.
Adverse event totals above are pulled from the FDA's Adverse Event Reporting System (FAERS). For these top-ranked reactions alone, cimetidine has 3,947 submissions while clozapine has 51,145. Those figures reflect cumulative reporting volume, not per-patient risk, so older, widely dispensed drugs typically look worse on count alone. These two drugs have a known minor interaction flagged in FDA labeling, attributed to cimetidine blocks the liver enzymes that normally clear clozapine from your body. this causes clozapine levels to rise, which can lead to more side effects.. Serious warnings, pregnancy guidance, and contraindications can differ even when indications overlap.
A table cannot represent individual circumstances. Data here is sourced from FDA Structured Product Labels (SPL) and FAERS, both of which update as manufacturers and clinicians submit new information. This registry does not provide medical, treatment, substitution, or medication-change directions for cimetidine or clozapine.
Registry boundary: This comparison displays source-record fields and does not provide individualized medical direction.