Chlorpromazine and Clozapine interaction
Chlorpromazine and Clozapine: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Clozapine (Clozaril) label · effective 2025-06-06
Proportion of Adult Subjects in Schizophrenia Studies with Weight Gain ≥7% Relative to Baseline Body Weight Weight change CLOZARIL Olanzapine Chlorpromazine N 669 442 155 ≥7% (inclusive) 236 (35%) 203 (46%) 13 (8%) 5.11 Neuroleptic Malignant Syndrome Antipsychotic drugs including CLOZARIL can cause a potentially fatal symptom complex referred to as Neuroleptic…
When possible, avoid concomitant use, with other anticholinergic medications because the risk for anticholinergic toxicity or severe gastrointestinal adverse reactions is increased [see Warnings and Precautions ( 5.7 ), Drug Interactions ( 7.1 )].
Drugs that cause QT prolongation include: specific antipsychotics (e.g., ziprasidone, iloperidone, chlorpromazine, thioridazine, mesoridazine, droperidol, pimozide), specific antibiotics (e.g., erythromycin, gatifloxacin, moxifloxacin, sparfloxacin), Class 1A antiarrhythmic medications (e.g., quinidine, procainamide) or Class III antiarrhythmics (e.g., amiodarone,…
A higher proportion of the CLOZARIL group demonstrated categorical increases from baseline in fasting glucose concentrations, compared to the chlorpromazine group ( Table 4 ).
The maximum chlorpromazine dose was 1800 mg per day (mean modal dose: 1029 mg per day).
From the Chlorpromazine (Chlorpromazine Hydrochloride) label · effective 2026-02-02
Long-Term Therapy To lessen the likelihood of adverse reactions related to cumulative drug effect, patients with a history of long-term therapy with chlorpromazine and/or other antipsychotics should be evaluated periodically to decide whether the maintenance dosage could be lowered or drug therapy discontinued.
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Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.