Drug interactions
Cimetidine + Difenoxin
Severity: Moderate
Cimetidine and Difenoxin: moderate 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 raise difenoxin exposure by slowing its hepatic breakdown. Higher levels could intensify opioid-type effects such as sedation and, in susceptible patients, CNS or respiratory depression.
What this interaction means in plain words
Cimetidine and Difenoxin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Cimetidine belongs to Gastrointestinal Tract; Difenoxin belongs to Gastrointestinal Tract.
Why it happens
Cimetidine inhibits hepatic CYP enzymes and may reduce the metabolic clearance of difenoxin; the effect is predicted rather than well studied.
What to do
Monitor for excessive sedation, constipation or respiratory depression, and use the lowest effective difenoxin dose. Consider an H2 blocker without CYP inhibition such as famotidine.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Cimetidine and Difenoxin, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 7 days on the web. No card needed.
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 Difenoxin
Frequently asked questions
Can I take Cimetidine with Difenoxin?
MediHelp rates the interaction as moderate. Cimetidine and Difenoxin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Cimetidine may raise difenoxin exposure by slowing its hepatic breakdown. Higher levels could intensify opioid-type effects such as sedation and, in susceptible patients, CNS or respiratory depression.
How serious is the interaction between Cimetidine and Difenoxin?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for excessive sedation, constipation or respiratory depression, and use the lowest effective difenoxin dose. Consider an H2 blocker without CYP inhibition such as famotidine.
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.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
