Tretinoin and Ketoconazole Topical: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Ketoconazole Topical
Tretinoin
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 tretinoin exposure and an increased risk of tretinoin-related adverse reactions
Interaction Deep Dive
Avoid concomitant use of tretinoin (CYP3A substrate) with ketoconazole (strong CYP3A inhibitor) if possible and monitor more frequently if concomitant use is unavoidable. Coadministration of tretinoin and ketoconazole may increase tretinoin exposure and may also increase risk of tretinoin-related adverse reactions. In a drug interaction study, tretinoin AUC increased by 72% following concomitant use with ketoconazole (strong CYP3A inhibitor). Increased tretinoin toxicity has also been reported post- marketing with strong CYP3A inhibitors including certain antimycotics1.
Why it happens (mechanism)
Inhibition of CYP3A-mediated metabolism of tretinoin
Literature reports
1 report — tap to read
a) In a drug interaction study, tretinoin AUC increased by 72% following concomitant use with ketoconazole (strong CYP3A inhibitor). Increased tretinoin toxicity has also been reported post- marketing with strong CYP3A inhibitors including certain antimycotics 1.
Common questions
Can I take Tretinoin and Ketoconazole Topical together?
Increased tretinoin exposure and an increased risk of tretinoin-related adverse reactions Always confirm with your pharmacist or prescriber before making any change.
How serious is the Tretinoin and Ketoconazole Topical interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "rapid". Effects can appear quickly, often within about 24 hours of combining the drugs.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Tretinoin or Ketoconazole Topical 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 (1)
- Product Information: VESANOID(R) oral capsules, tretinoin oral capsules. H2-Pharma, LLC (per FDA), Montgomery, AL, 2024. DailyMed
Keep reading about Ketoconazole Topical
Keep reading about Tretinoin
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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