Miconazole and Acenocoumarol: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Acenocoumarol
No brand names on recordMiconazole
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
Concomitant administration of oral and intravenous miconazole and coumarin anticoagulants has resulted in enhancement of the anticoagulant effect125. Three case reports describe patients previously stabilized on acenocoumarol who experienced increased international normalized ratio (INR) values following the use of oral miconazole gel for oral candidiasis 3.
Why it happens (mechanism)
Inhibition of cytochrome P450-mediated acenocoumarol metabolism
Literature reports
2 reports — tap to read
a) Acenocoumarol is the 4'-nitro analog of warfarin and is metabolized by cytochrome P450 (CYP) 2C9, 3A4, and 1A2 isoenzymes. Miconazole exhibits its fungistatic activity by inhibiting the fungal CYP enzymatic activity, and is also believed to be capable of inhibiting several CYP isoenzymes in the host when administered systemically. Three patients experienced increased anticoagulant activity following the addition of miconazole oral gel. Patient 1, a 62-year-old female stabilized on acenocoumarol for more than seven years, was prescribed miconazole oral gel 100 mg four times daily for oral candidiasis. Fifteen days later, her international normalized ratio (INR) had increased from 2.48 to 13.7. The second patient, an 89-year-old female, had an increase in her INR from 2.30 to 12.00 15 days after starting miconazole oral gel 100 mg four times daily. She had been stabilized on acenocoumarol for more than two years. Patient 3, a 43-year-old male, was prescribed miconazole oral gel 100 mg four times daily for oral candidiasis. His acenocoumarol dose and INR had been stable during the previous two months. Five days after initiating miconazole, his INR increased from 2.07 to 6.88. None of the three patients experienced a bleeding episode, but the first two patients were given phytonadione to accelerate the reversal of the INR 3.
b) Two patients experienced an increase in their International Normalized Ratio (INR) values after the administration of vaginal miconazole. The first woman, 61 years of age, had a stable acenocoumarol dose for four years. She was prescribed vaginal miconazole 400 mg daily for three consecutive days for vaginitis. An INR measurement on the day following the treatment with miconazole revealed an INR of 7.4. The second woman, a 72-year-old female with candida vaginitis, had been stabilized on acenocoumarol when vaginal miconazole 400 mg once daily for three days was prescribed. Six days following the end of treatment with miconazole, her INR was 8.3. The authors suggest that an inflamed postmenopausal atrophic vaginal epithelium may have caused an increase in miconazole systemic absorption, thus potentiating acenocoumarol 4.
Common questions
Can I take Miconazole and Acenocoumarol together?
An increased risk of bleeding Always confirm with your pharmacist or prescriber before making any change.
How serious is the Miconazole and Acenocoumarol 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 Miconazole or Acenocoumarol 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 (5)
- Watson PG, Lochan RG, & Redding VJ: Drug interactions with coumarin derivative anticoagulants (letter). Br Med J 1982; 285:1045-1046. PubMed
- Colquhoun MC, Daly M, Stewart P, et al: Interaction between warfarin and miconazole oral gel (letter). Lancet 1987; 1:695-696. PubMed
- Ortin M, Olalla JI, Muruzabal MJ, et al: Miconazole oral gel enhances acenocoumarol anticoagulant activity: a report of three cases. Ann Pharmacother 1999; 33:175-177. PubMed
- Lansdorp D, Bressers HPHM, Dekens-Konter JAM, et al: Potentiation of acenocoumarol during vaginal administration of miconazole. Br J Clin Pharmacol 1999; 47:225-226.
- Product Information: Monistat(R), miconazole. Janssen Pharmaceutica Inc. Piscataway, NJ, 1993. DailyMed
Keep reading about Acenocoumarol
Keep reading about Miconazole
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