Cobicistat and Ketoconazole Topical: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Cobicistat
Ketoconazole Topical
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 cobicistat exposure and an increased ketoconazole exposure
Interaction Deep Dive
Use caution when cobicistat (strong CYP3A4 inhibitor and CYP3A4 substrate) is coadministered with oral ketoconazole (CYP3A4 substrate and strong CYP3A4 inhibitor)1, as it may lead to increased exposure of cobicistat, ketoconazole, or both. Monitor for increased cobicistat and/or ketoconazole adverse reactions 3. If concomitant use is necessary, do not exceed a maximum daily ketoconazole dose of 200 mg/day 2.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism of cobicistat; inhibition of CYP3A4-mediated metabolism of ketoconazole
Common questions
Can I take Cobicistat and Ketoconazole Topical together?
Increased cobicistat exposure and an increased ketoconazole exposure Always confirm with your pharmacist or prescriber before making any change.
How serious is the Cobicistat 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 "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.
Questions for your pharmacist
- Does my dose of Cobicistat 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 (3)
- Product Information: Ketoconazole oral tablet, ketoconazole oral tablet. Taro Pharmaceuticals U.S.A. Inc. (per DailyMed), Hawthorne, NY, 2024. DailyMed
- Product Information: STRIBILD(R) oral tablets, elvitegravir cobicistat emtricitabine tenofovir disoproxil fumarate oral tablets. Gilead Sciences Inc (per FDA), Foster City, CA, 2021. DailyMed
- Product Information: SYMTUZA(R) oral tablets, darunavir, cobicistat, emtricitabine, tenofovir alafenamide oral tablets. Janssen Products, LP (per FDA), Horsham, PA, 2023. DailyMed
Keep reading about Cobicistat
Keep reading about Ketoconazole Topical
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Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
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