Drug interactions
Fosaprepitant + Oxybutynin
Severity: Minor
Fosaprepitant and Oxybutynin: 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
Aprepitant, the active form of fosaprepitant, is a moderate CYP3A4 inhibitor after a single dose and may slightly raise oxybutynin exposure. Because use is brief, the effect is likely small.
What this interaction means in plain words
Fosaprepitant and Oxybutynin have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Fosaprepitant belongs to Gastrointestinal Tract; Oxybutynin belongs to Genitourinary.
Why it happens
Aprepitant transiently inhibits CYP3A4, reducing oxybutynin metabolism.
What to do
No dose change is needed; monitor for increased anticholinergic effects for several days after dosing.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Fosaprepitant and Oxybutynin, 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 Oxybutynin
Other interactions of Fosaprepitant
- Flibanserin + Fosaprepitant Contraindicated
- Fosaprepitant + Pimozide Contraindicated
- Alprazolam + Fosaprepitant Moderate
- Amiodarone + Fosaprepitant Moderate
- Amobarbital + Fosaprepitant Moderate
- Apalutamide + Fosaprepitant Moderate
Frequently asked questions
Can I take Fosaprepitant with Oxybutynin?
MediHelp rates the interaction as minor. Fosaprepitant and Oxybutynin have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Aprepitant, the active form of fosaprepitant, is a moderate CYP3A4 inhibitor after a single dose and may slightly raise oxybutynin exposure. Because use is brief, the effect is likely small.
How serious is the interaction between Fosaprepitant and Oxybutynin?
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 dose change is needed; monitor for increased anticholinergic effects for several days after dosing.
What other medicines interact with Oxybutynin?
MediHelp also lists interactions of Oxybutynin with, for example, Bethanechol, Clozapine, Potassium chloride. The full list is on the Oxybutynin 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.
