Anisindione 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
Anisindione
No brand names on record
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
An increased risk of bleeding
Interaction Deep Dive
The manufacturer cautions that ketoconazole may enhance the anticoagulant effect of coumarin-like drugs3. In contrast, no hypothrombinemic interaction was found in two volunteers receiving ketoconazole 200 mg plus warfarin 7.5 mg to 15 mg for three weeks 1.
Why it happens (mechanism)
Decreased anisindione metabolism
Literature reports
2 reports — tap to read
a) Ketoconazole has been reported to potentiate the anticoagulant effect of warfarin in a single case study 2. A 75-year-old woman stabilized on warfarin for three years was administered ketoconazole 200 mg twice daily for a chronic vaginal thrush infection. Three weeks after treatment, the patient was noted to have spontaneous bleeding and a decrease in her coagulation control. The patient was receiving no other drugs and had normal liver function tests and CBC. Treatment consisted of stopping ketoconazole therapy and reducing the warfarin dosage. Warfarin control was reestablished at her previous dosage level over the next three weeks.
b) Patients treated with warfarin may need a reduction in dosage by one-third with concurrent administration of ketoconazole 2.
Common questions
Can I take Anisindione and Ketoconazole Topical together?
An increased risk of bleeding Always confirm with your pharmacist or prescriber before making any change.
How serious is the Anisindione and Ketoconazole Topical interaction?
It is rated moderate. Can be significant — usually manageable with monitoring.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
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 Anisindione 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 anything you'd monitor while I'm on both?
References (3)
- Brass C, Galgiani JN, Blaschke TF, et al: Disposition of ketoconazole, an oral antifungal, in humans. Antimicrob Agents Chemother 1982; 21:151-158. PubMed
- Smith AG: Potentiation of oral anticoagulants by ketoconazole. Br Med J 1984; 288:188-189. PubMed
- Product Information: Nizoral(R), ketoconazole. Janssen Pharmaceutica Inc. Titusville, NJ, 1998. DailyMed
Keep reading about Ketoconazole Topical
Keep reading about Anisindione
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:
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