Azithromycin and Mifepristone: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Jul 11, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Mifepristone
Azithromycin
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.
What happens
Increased miFEPRIStone exposure and an increased risk of QT interval prolongation
Interaction Deep Dive
Avoid coadministration of miFEPRIStone with other drugs that prolong QT. MiFEPRIStone and its metabolites block IKr. MiFEPRIStone prolongs the QTc interval in a dose related manner. There is little or no experience with high exposure, concomitant dosing with other QT prolonging drugs, or potassium channel variants resulting in a long QT interval3. Exert caution when miFEPRIStone is coadministered with azithromycin (CYP3A4 inhibitor) 34 as it may increase miFEPRIStone exposure. Dose reduction of miFEPRIStone may be required. Due to the long half-life of miFEPRIStone, wait at least 2 weeks after stopping miFEPRIStone before initiating azithromycin. However, if concomitant use is necessary, use the lowest effective dose possible. Carefully weigh the benefit of concomitant use of these agents against the potential risks. Limit the dose of miFEPRIStone to 900 mg 3. Consider the risk of QT prolongation which can be fatal when initiating azithromycin in patients taking drugs that may prolong the QT interval, such as miFEPRIStone 21.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism of miFEPRIStone; additive QT interval prolongation
Common questions
Can I take Azithromycin and Mifepristone together?
Increased miFEPRIStone exposure and an increased risk of QT interval prolongation Always confirm with your pharmacist or prescriber before making any change.
How serious is the Azithromycin and Mifepristone interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
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 Azithromycin or Mifepristone 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 (4)
- Product Information: ZMAX(R) oral extended-release suspension, azithromycin oral extended-release suspension. Pfizer Inc (per FDA), New York, NY, 2021. DailyMed
- Product Information: ZITHROMAX(R) intravenous injection, azithromycin intravenous injection. Pfizer Labs (per FDA), New York, NY, 2016. DailyMed
- Product Information: KORLYM(R) oral tablets, mifepristone oral tablets. Corcept Therapeutics Incorporated (per Dailmed), Redwood City, CA, 2024. DailyMed
- Product Information: MIFEPREX(R) oral tablets, mifepristone oral tablets. Danco Laboratories, LLC (per FDA), New York, NY, 2023. DailyMed
Keep reading about Mifepristone
Keep reading about Azithromycin
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.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist