Drug interactions
Chlorpromazine + Cimetidine
Severity: Minor
Chlorpromazine and Cimetidine: minor interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Cimetidine can raise chlorpromazine concentrations, potentially increasing sedation, hypotension and anticholinergic effects. Effects are variable and usually modest.
What this interaction means in plain words
Chlorpromazine and Cimetidine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Chlorpromazine belongs to Central Nervous System; Cimetidine belongs to Gastrointestinal Tract.
Why it happens
Cimetidine inhibits CYP2D6 and other hepatic oxidative pathways that metabolize chlorpromazine.
What to do
Monitor for excess sedation, orthostatic hypotension and extrapyramidal effects, and reduce the chlorpromazine dose if these occur.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Cimetidine
- Cimetidine + Dofetilide Contraindicated
- Cimetidine + Fezolinetant Contraindicated
- Alfentanil + Cimetidine Major
- Atazanavir + Cimetidine Major
- Carmustine + Cimetidine Major
- Cimetidine + Citalopram Major
Other interactions of Chlorpromazine
- Chlorpromazine + Dofetilide Contraindicated
- Chlorpromazine + Dronedarone Contraindicated
- Chlorpromazine + Droperidol Contraindicated
- Chlorpromazine + Ibutilide Contraindicated
- Chlorpromazine + Metrizamide Contraindicated
- Chlorpromazine + Panobinostat Contraindicated
Frequently asked questions
Can I take Chlorpromazine with Cimetidine?
MediHelp rates the interaction as minor. Chlorpromazine and Cimetidine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Cimetidine can raise chlorpromazine concentrations, potentially increasing sedation, hypotension and anticholinergic effects. Effects are variable and usually modest.
How serious is the interaction between Chlorpromazine and Cimetidine?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for excess sedation, orthostatic hypotension and extrapyramidal effects, and reduce the chlorpromazine dose if these occur.
What other medicines interact with Cimetidine?
MediHelp also lists interactions of Cimetidine with, for example, Dofetilide, Fezolinetant, Alfentanil. The full list is on the Cimetidine page.
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