Miconazole and Warfarin: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Warfarin
Miconazole
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 warfarin exposure, an increased INR and an increased risk of bleeding
Interaction Deep Dive
Miconazole is a CYP2C9 and CYP3A4 inhibitor1 and concomitant use with warfarin (a CYP2C9 and CYP3A4 substrate) 13 may result in increased warfarin exposure and effect (ie, increased INR and risk of bleeding). Concomitant administration of oral, topical, and vaginal formulations of miconazole and coumarin anticoagulants has resulted in enhancement of the anticoagulant effect1. If miconazole therapy is required in a patient taking warfarin, more frequent monitoring of INR, prothrombin time, and other appropriate anticoagulant tests, along with signs of bleeding is recommended 1, especially when miconazole is initiated and discontinued 13. Consider the CYP2C9 inhibition potential when starting, stopping, or changing dose of concomitant medications 3.
Why it happens (mechanism)
Inhibition of CYP2C9-mediated metabolism of warfarin; inhibition of CYP3A4-mediated metabolism of warfarin
Literature reports
10 reports — tap to read
a) A significant increase in mean INR of 1.27 (95% CI, 0.94 to 1.59) was observed in patients on warfarin who initiated treatment with oral miconazole gel for oral candidiasis (n=330). The proportion of patients with an INR greater than 5 following initiation of oral miconazole gel significantly increased from 5.5% to 30.1%. The maximum INR increase was seen 1.5 weeks after miconazole initiation and normalized after 5 weeks. Miconazole is a strong inhibitor of CYP2C9, which catalyzes the metabolism of warfarin and leads to higher INR values 6.
b) Initiation of antibiotics in patients on continuous warfarin therapy resulted in a significantly increased risk of serious bleeding requiring hospitalization according to a nested case-control study of United States Medicare part D beneficiaries aged 65 years and older (n=38,762). Patients on warfarin who received any antibiotic were twice as likely to be hospitalized for bleeding compared with matched controls on warfarin who were not exposed to antibiotics (adjusted odds ratio (aOR), 2.01; 95% CI, 1.62 to 2.5). Additionally, continuous-warfarin users were twice as likely to have a bleeding event that required hospitalization within 60 days of antibiotic exposure compared with non-exposure. Antibiotic exposure greater than 60 days from the index bleed was not significantly associated with increased risk of bleeding. Specific antibiotics with the highest bleeding risk were azole antifungals (aOR, 4.57; 95% CI, 1.9 to 11.03), followed by cotrimoxazole (aOR, 2.7; 95% CI, 1.46 to 5.05), cephalosporins (aOR, 2.45; 95% CI, 1.52 to 3.95), penicillins (aOR, 1.92; 95% CI, 1.21 to 2.07), macrolides (aOR, 1.86; 95% CI, 1.08 to 3.21), and quinolones (aOR, 1.69; 95% CI, 1.09 to 2.62) 4.
c) Concomitant administration of oral warfarin 1 mg daily and miconazole oral gel 5 mL 4 times daily was reported to result in potentiation of the hypoprothrombinemic effects of warfarin. It was suspected that sufficient miconazole was absorbed from the oral mucosa to potentiate the effects of warfarin, presumably secondary to inhibition of hepatic metabolism 2.
d) A case report describes an interaction between warfarin and miconazole oral gel in a 73-year-old man. The patient had been taking warfarin 1 mg to 3 mg daily for several years in addition to metoprolol, dilTIAZem, aspirin, isosorbide, and omeprazole. After using oral miconazole gel 125 mg for oral candidiasis 4 times a day for 2 weeks, the patient's INR increased from 1.5 to over 10. After discontinuation of warfarin and miconazole, the patient's INR decreased to 3 over the next 2 weeks. Warfarin was then reinstated at 2 mg daily and the patient's INR remained well-controlled in the range of 2 to 3 7.
e) A 53-year-old woman who underwent mitral valve replacement was stabilized on warfarin 45 mg weekly with a mean corresponding INR of 2.69 for 18 months. Because of a vaginal yeast infection, a 3-day course of miconazole 200 mg vaginal suppositories was prescribed. On the third day of miconazole treatment, she presented to the anticoagulation clinic with complaints of ecchymosis on her legs and arms. Her INR was measured to be 9.77. Warfarin was withheld for a day, and her INR dropped to 6.93 the next day. Because of the persistence of her vaginal infection, a 7-day course of miconazole 100 mg suppositories was prescribed later the same week. The warfarin dose was empirically decreased 32.5 mg weekly, and 6 days later her INR was 3.27. She resumed her regular warfarin dose after the second course of miconazole, and was stabilized on such until another yeast infection developed a year later. Her warfarin dose was empirically reduced by 19% in anticipation of an interaction with another 7-day course of miconazole 100 mg vaginal suppositories. Her INR five days later was 7.13. Although only 1.4% of a vaginally administered miconazole dose is systemically absorbed in healthy volunteers, other factors such as dietary changes were ruled out as the cause of her supratherapeutic INR values 8.
f) Three case reports of potentiation of warfarin anticoagulant activity with concomitant use of miconazole oral gel and warfarin. All 3 patients were compliant with their medication and attended the anticoagulation clinic regularly. Between 7 and 15 days after initiation of treatment with oral miconazole gel, the INR of each patient increased significantly. Warfarin and oral miconazole gel were subsequently discontinued and INR values reversed. Anticoagulation returned to desired values upon reinitiation of warfarin treatment 9.
g) The US Food and Drug Administration has issued a warning regarding the use of the warfarin and vaginal miconazole preparations after reports of abnormal clotting tests in woman taking both agents 10.
h) A case report describes an 80 year-old man who had been on chronic warfarin therapy for atrial fibrillation. He had been taking 6 mg daily over the last 12 months which had kept his INR between 2.2 and 3.1. At his routine appointment his INR was found to be 21.4 without evidence of bruising or bleeding. Other medications included atenolol, isosorbide mononitrate 20 mg, and dilTIAZem 400 mg. Over the previous 2 weeks he had been using topical miconazole for a fungal infection in his right groin area. After being admitted to the hospital his warfarin and miconazole were withdrawn and he was administered fresh frozen plasma. His INR returned to 3.2 and warfarin 6 mg/day was reinstated 5 days later. Since his discharge he has remained on warfarin 6 mg/day with a stable INR. The author concludes that topical absorption of miconazole had occurred which led to loss of anticoagulant control. If topical miconazole cannot be avoided during warfarin treatment, close monitoring of anticoagulant therapy is advised 11.
i) A 73-year-old woman who was previously well was found to have a retroperitoneal hematoma on CT scan after experiencing severe lower abdominal pain and profuse vomiting. She was on long-term warfarin therapy for previous pulmonary embolism, and had been prescribed oral miconazole by her dentist 2 days prior to hospital presentation. She also had a submucosal intramural hematoma as revealed by small bowel enema. She was hospitalized for 3 weeks 12.
j) Cases of bleeding and bruising following the concomitant use of warfarin and topical, intravaginal, or oral miconazole were reported 1.
Common questions
Can I take Miconazole and Warfarin together?
Increased warfarin exposure, an increased INR and an increased risk of bleeding Always confirm with your pharmacist or prescriber before making any change.
How serious is the Miconazole and Warfarin interaction?
It is rated major. Potentially serious — often needs a change or close 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 "established". Well documented — supported by controlled studies or strong clinical data.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Miconazole or Warfarin 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 (13)
- Product Information: ORAVIG(R) buccal tablets, miconazole buccal tablets. DARA BioSciences Inc (per manufacturer), Raleigh, NC, 2015.
- Colquhoun MC, Daly M, Stewart P, et al: Interaction between warfarin and miconazole oral gel (letter). Lancet 1987; 1:695-696. PubMed
- Product Information: WARFARIN SODIUM oral tablets, warfarin sodium oral tablets. Teva Pharmaceuticals (per Dailymed), Parsippany, NJ, 2023. DailyMed
- Baillargeon J, Holmes HM, Lin YL, et al: Concurrent use of warfarin and antibiotics and the risk of bleeding in older adults. Am J Med 2012; 125(2):183-189. PubMed
- Product Information: COUMADIN(R) oral tablets, intravenous injection powder lyophilized for solution, warfarin sodium oral tablets, intravenous injection powder lyophilized for solution. Bristol-Myers Squibb Company (per FDA), Princeton, NJ, 2011. DailyMed
- Iversen DB, Hellfritzsch M, Stage TB, et al: Antimycotic treatment of oral candidiasis in warfarin users. Am J Med 2021; 134(5):e308-e312. PubMed
- Ariyaratnam S, Thakker NS, Sloan P, et al: Potentiation of warfarin anticoagulant activity by miconazole oral gel. Br Med J 1997; 314:349.
- Thirion DJG & Farquhar Zanetti LA: Potentiation of warfarin's hypoprothrombinemic effect with miconazole vaginal suppositories. Pharmacotherapy 2000; 20:98-99. PubMed
- Silingardi M, Ghirarduzzi A, Tincani E, et al: Miconazole oral gel potentiates warfarin anticoagulant activity (letter). Thromb Haemost 2000; 83:794-795. DOI
- Anon: FDA updates safety information of miconazole vaginal cream. Food and Drug Administration. Rockville, MD. 2001.
- Devaraj A, O'Beirne JP, Veasey R, et al: Interaction between warfarin and topical miconazole cream. Br Med J 2002; 325:77. PubMed
- Marco M & Guy AJ: Retroperitoneal haematoma and small bowel intramural haematoma caused by warfarin and miconazole interaction (letter). Int J Oral Maxillofac Surg 1997; 27:485. PubMed
- Product Information: COUMADIN(R) oral tablets, warfarin sodium oral tablets. Bristol-Myers Squibb Company (per manufacturer), Princeton, NJ, 2019. DailyMed
Keep reading about Warfarin
Keep reading about Miconazole
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