Mifepristone and Clindamycin: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 1, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Mifepristone
Clindamycin
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
Here's what's going on. Mifepristone (Korlym) is a strong blocker of a liver enzyme called CYP3A4. Clindamycin (Cleocin) is partly broken down by that same enzyme. When you take both, clindamycin may not get cleared as fast, so more of it can build up in your body. That could mean a higher chance of side effects like stomach upset or diarrhea.
This is flagged as a serious combination on paper, though it's based mostly on how the drugs work rather than lots of patient reports. One important point: mifepristone leaves the body very slowly, so this effect can linger for weeks. The good news is your care team can manage this by adjusting doses or watching you more closely. Please talk with your pharmacist or doctor.
Mechanism: Mifepristone is a strong CYP3A4 inhibitor; clindamycin is a CYP3A4 substrate. Inhibition reduces clindamycin metabolism, increasing its exposure (AUC/Cmax) and the potential for concentration-related adverse effects.
- Direction: Increased clindamycin exposure (increases_drug_effect).
- Severity on file: Contraindicated; evidence is theoretical/PK-based.
- Onset: Unspecified; effect prolonged due to mifepristone's long terminal half-life.
- Management: Avoid coadministration where possible. If used together, consider clindamycin dose reduction or discontinuation and closer monitoring. Because of slow mifepristone elimination, allow at least 2 weeks after stopping mifepristone before initiating an NTI CYP3A4 substrate.
What happens
Increased CYP3A4 substrate with NTI exposure
Interaction Deep Dive
The concurrent use of miFEPRIStone (a strong CYP3A4 inhibitor) (Korlym®) with CYP3A4 substrates that have a narrow therapeutic index (NTI) is contraindicated, since it can raise the exposure of these NTI CYP3A4 substrates. Should they be given together, it may be necessary to stop or lower the dose of the CYP3A4 substrates with NTI 1. Caution is nonetheless warranted when miFEPRIStone (Mifeprex®) is administered alongside CYP3A4 substrates with NTI. Because miFEPRIStone is cleared from the body slowly, this interaction can persist for an extended time following its administration 2. Given miFEPRIStone's long terminal half-life once steady state is achieved, at least 2 weeks should pass after discontinuing miFEPRIStone before starting CYP3A4 substrates with NTI 1.
Why it happens (mechanism)
Inhibition of CYP3A4-substrate metabolism by miFEPRIStone
How to manage this interaction
What your care team may do:
- Avoid using these two together when possible, since this pairing is flagged as contraindicated.
- If both are needed, your clindamycin dose may need to be adjusted and individualized by your care team, and they may monitor you more closely for side effects.
- Because mifepristone stays in your body a long time, this caution can apply for a couple of weeks after stopping it.
What you should do: Keep taking both exactly as prescribed unless told otherwise, and let your pharmacist or prescriber know you take both so they can plan timing and monitoring.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) In a drug interaction study, giving miFEPRIStone 1200 mg once daily for 10 days together with a single 80 mg dose of simvastatin (a CYP3A4 substrate) led to increases in simvastatin AUC and Cmax of 10.40-fold and 7.02-fold, respectively. It also produced increases in simvastatin acid AUC and Cmax of 15.7-fold and 18.20, respectively 1.
Common questions
Can I take Mifepristone and Clindamycin together?
Mifepristone can raise clindamycin levels by blocking its breakdown, and this combo is flagged as one to avoid. Do not change anything on your own; check with your pharmacist or doctor about dosing and monitoring. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Mifepristone and Clindamycin interaction?
It is rated contraindicated. These should generally not be used together.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How is the Mifepristone and Clindamycin interaction managed?
What your care team may do: Avoid using these two together when possible, since this pairing is flagged as contraindicated. If both are needed, your clindamycin dose may need to be adjusted and individualized by your care team, and they may monitor you more closely for side effects. Because mifepristone stays in your body a long time, this caution can apply for a couple of weeks after stopping it.… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Mifepristone or Clindamycin need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (2)
Keep reading about Mifepristone
Keep reading about Clindamycin
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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