Chlorpromazine and Clozapine Interaction
Drug interaction information between Chlorpromazine and Clozapine.
Chlorpromazine and Clozapine have a documented minor interaction in FDA labeling.
FDA drug labeling documents a minor-severity interaction between Chlorpromazine and Clozapine. Major interactions are generally avoided, moderate ones may need monitoring or a dose adjustment, and minor ones are usually low-risk. This page shows the documented mechanism and guidance. Label-documented interactions are not a complete safety review, so always confirm your own medications with a pharmacist or doctor. Educational information, not medical advice.
How They Interact
These two drugs both affect the heart's electrical system in the same way. Using them at the same time can lead to serious heart rhythm problems.
What To Do
Your healthcare provider should perform regular heart tests while you are on both medications. They may need to adjust your treatment if they see changes in your heart rhythm.
FDA Label Information
Drugs that cause QT prolongation include: specific antipsychotics (e.g., ziprasidone, iloperidone, chlorpromazine, thioridazine, mesoridazine, droperidol, and pimozide), specific antibiotics (e.g., erythromycin, gatifloxacin, moxifloxacin, sparfloxacin), Class 1A antiarrhythmics (e.g., quinidine, procainamide) or Class III antiarrhythmics (e.g., amiodarone, sotalol), and others (e.g., pentamidine, levomethadyl acetate, methadone, halofantrine, mefloquine, dolasetron mesylate, probucol or tacrolimus) [see Warnings and Precautions (5.9) ] .
Chlorpromazine Also Interacts With
- Desmopressin moderate
- Tetrabenazine moderate
- Tranylcypromine moderate
- Zolpidem moderate
- Carbamazepine minor
Clozapine Also Interacts With
- Cyclobenzaprine moderate
- Diphenhydramine moderate
- Fluoxetine moderate
- Sertraline minor
- Escitalopram minor
Frequently Asked Questions
Can I take Chlorpromazine and Clozapine together?
This is a minor interaction. Your healthcare provider should perform regular heart tests while you are on both medications. They may need to adjust your treatment if they see changes in your heart rhythm.
How serious is the interaction between Chlorpromazine and Clozapine?
This interaction is classified as "minor" severity by the FDA. Minor interactions are unlikely to cause significant problems but should still be mentioned to your healthcare provider.
Why do Chlorpromazine and Clozapine interact?
These two drugs both affect the heart's electrical system in the same way. Using them at the same time can lead to serious heart rhythm problems.
Understanding the Chlorpromazine and Clozapine Interaction
FDA-approved prescribing information for these two drugs flags their combination as a minor-severity interaction. Chlorpromazine belongs to the Typical Antipsychotic (Phenothiazine) class and Clozapine belongs to the Atypical Antipsychotic class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: These two drugs both affect the heart's electrical system in the same way. Severity tiers matter: major flags generally advise avoidance, moderate flags often require monitoring or dose adjustment, and minor flags may only call for awareness.
Context around a specific patient determines real-world impact. Chlorpromazine has 11 total documented interactions on file in this dataset, and Clozapine has 42. Each additional medication compounds the interaction surface, which is why pharmacists run full-profile checks rather than evaluating one pair at a time. FDA-derived guidance for this pair is: Your healthcare provider should perform regular heart tests while you are on both medications. Timing of doses, renal and hepatic function, age, and other concurrent prescriptions all shape whether a labeled interaction matters clinically.
An interaction flag is not a verdict. A large share of labeled interactions are managed routinely in clinical practice, the fix may be as simple as spacing doses or adding a monitoring test. Others require the prescriber to choose a different medication entirely. This page surfaces FDA-sourced labeling and openFDA data for educational purposes only; it is not medical advice and cannot account for your full clinical picture. Never start, stop, or adjust either Chlorpromazine or Clozapine based on a web page, speak with your prescriber or pharmacist before making any change.
Sources: FDA Drug Labels (SPL) via openFDA (2026). This is for informational purposes only and is not medical advice. Always consult your healthcare provider about drug interactions.
Read our methodology - how this data is sourced, computed, and verified.