Drug interactions
Cimetidine + Diphenoxylate-atropine
Severity: Minor
Cimetidine and Diphenoxylate-atropine: 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
Diphenoxylate is metabolized by hepatic enzymes to difenoxin, and cimetidine inhibits several CYP enzymes. Raised levels could lead to more opioid and anticholinergic effects such as sedation and constipation. The clinical significance is generally modest.
What this interaction means in plain words
Cimetidine and Diphenoxylate-atropine 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 belongs to Gastrointestinal Tract; Diphenoxylate-atropine belongs to Gastrointestinal Tract.
Why it happens
Cimetidine inhibits hepatic CYP-mediated metabolism of diphenoxylate, potentially raising its exposure.
What to do
No routine change is needed; monitor for excess sedation or anticholinergic effects. Consider ranitidine-free or famotidine alternatives if concerned.
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 Diphenoxylate-atropine
- Diphenoxylate-atropine + Isocarboxazid Contraindicated
- Diphenoxylate-atropine + Phenelzine Contraindicated
- Diphenoxylate-atropine + Tranylcypromine Contraindicated
- Alfentanil + Diphenoxylate-atropine Major
- Alvimopan + Diphenoxylate-atropine Major
- Amitriptyline + Diphenoxylate-atropine Major
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 Diphenoxylate-atropine?
MediHelp rates the interaction as minor. Cimetidine and Diphenoxylate-atropine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Diphenoxylate is metabolized by hepatic enzymes to difenoxin, and cimetidine inhibits several CYP enzymes. Raised levels could lead to more opioid and anticholinergic effects such as sedation and constipation. The clinical significance is generally modest.
How serious is the interaction between Cimetidine and Diphenoxylate-atropine?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: No routine change is needed; monitor for excess sedation or anticholinergic effects. Consider ranitidine-free or famotidine alternatives if concerned.
What other medicines interact with Diphenoxylate-atropine?
MediHelp also lists interactions of Diphenoxylate-atropine with, for example, Isocarboxazid, Phenelzine, Tranylcypromine. The full list is on the Diphenoxylate-atropine page.
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