Drug interactions
Cimetidine + Promazine
Severity: Minor
Cimetidine and Promazine: 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 may increase promazine levels by reducing its metabolism, which could heighten sedation, hypotension and anticholinergic effects.
What this interaction means in plain words
Cimetidine and Promazine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Why it happens
Cimetidine inhibits CYP2D6 and other CYP enzymes involved in phenothiazine metabolism.
What to do
Monitor for excess sedation, hypotension and extrapyramidal effects, and reduce the promazine dose if they 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
Frequently asked questions
Can I take Cimetidine with Promazine?
MediHelp rates the interaction as minor. Cimetidine and Promazine 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 may increase promazine levels by reducing its metabolism, which could heighten sedation, hypotension and anticholinergic effects.
How serious is the interaction between Cimetidine and Promazine?
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, hypotension and extrapyramidal effects, and reduce the promazine dose if they 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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