What the FDA labels say about taking them together
Cimetidine and clozapine
Clozapine's FDA label of June 6, 2025 names cimetidine in its drug interactions section; the cimetidine label PlainMeds reads does not name clozapine. The clozapine label: “CYP2D6 and CYP3A4 Inhibitors Concomitant treatment with CLOZARIL and CYP2D6 or CYP3A4 inhibitors can increase clozapine levels and lead to adverse reactions.”
Check it at the source: the cimetidine FDA label on DailyMed (effective July 15, 2026, Mylan Pharmaceuticals Inc.); the clozapine FDA label on DailyMed (effective June 6, 2025, HLS Therapeutics (USA), Inc.).
What does the cimetidine label say about clozapine?
Cimetidine's label (effective July 15, 2026) does not name clozapine in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Cimetidine), Mylan Pharmaceuticals Inc., effective July 15, 2026 (SPL set 06c0a509-026f-44e0-9975-a94a8de51d43), via openFDA; the full label on DailyMed
What does the clozapine label say about cimetidine?
Clozapine label, drug interactionsCYP2D6 and CYP3A4 Inhibitors Concomitant treatment with CLOZARIL 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 )].
Source: FDA drug label (Versacloz, NDA203479), TruPharma LLC, effective September 6, 2026 (SPL set 2592c9a8-fd74-4e0d-a895-b07b014cf355), via openFDA
Source: FDA drug label (Clozaril), NDA019758 (Heritage Life), as published by HLS Therapeutics (USA), Inc., effective June 6, 2025 (SPL set 90876802-0e3a-44c9-9ff7-1754dfbe736a), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Cimetidine | Clozapine | |
|---|---|---|
| Labeled for | Acid reflux and ulcers | Schizophrenia |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | $0.236 per tablet 300 mg tablet | $0.610 per tablet 100 mg tablet |
| Shortage now | No current entry | No current entry |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once