Danazol and Anisindione: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Danazol
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
Increased risk of bleeding
Interaction Deep Dive
A number of case reports have demonstrated that coadministration of oral anticoagulants and 17-alkylated androgens (fluoxymesterone, oxandrolone, oxymetholone, methyltestosterone, methandrostenolone, stanozolol) has resulted in a prolonged prothrombin time and hemorrhages12345. Three case reports of danazol potentiating the effects of warfarin, including bleeding complications, have been reported 76.
Why it happens (mechanism)
Unknown
Literature reports
3 reports — tap to read
a) Anabolic steroids have been well documented to cause important interactions with dicumarol. The anabolic steroids enhance dicumarol's anticoagulant activity perhaps through reductions in clotting factor formation and increased clotting factor degradation. The 17-alpha-alkylated steroids (fluoxymesterone, oxandrolone, oxymetholone, methyltestosterone, methandrostenolone, stanozolol) appear to be more likely to induce this reaction than the non-substituted steroids 12345.
b) Increased prothrombin time and hematemesis was reported in a 40-year-old female receiving warfarin for a prosthetic mitral valve and danazol for endometriosis 6. The patient had been receiving long-term anticoagulation therapy with warfarin 6 mg daily. Her prothrombin ratio was 2.3. Three weeks before admission the patient was started on danazol 200 mg twice daily for endometriosis. On admission her prothrombin ratio was 14. The patient presented with a history of hematemesis and easy bruising secondary to a loss of anticoagulant control. Five years earlier the patient had also been concomitantly treated with danazol and warfarin and experienced a prothrombin ratio of 18. Anticoagulant control returned to normal following withdrawal of danazol therapy. Lack of anticoagulant control was therefore attributed to the combination of danazol and warfarin therapy. A definite causal relationship between an increased prothrombin time with concomitant danazol and warfarin therapy in this patient was not established.
c) Two cases have been reported in which danazol potentiated the effect of warfarin, causing bleeding complications. In the first case, a 47-year old woman had been taking alternating daily 5 mg and 4 mg warfarin doses. One month after danazol 200 mg twice daily had been added to her regimen for menorrhagia, she presented to the emergency room with gross hematuria. Her prothrombin time (PT) was measured to be 48.2 seconds, and two days later was 55.7 seconds. Both medications were discontinued. The patient was later rechallenged with danazol and required decreased warfarin doses (between 1.25 mg and 2.5 mg daily) to maintain a therapeutic PT 7.
Common questions
Can I take Danazol and Anisindione together?
Increased risk of bleeding Always confirm with your pharmacist or prescriber before making any change.
How serious is the Danazol and Anisindione 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 "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Danazol or Anisindione 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 (7)
- Schrogie JJ & Solomon HM: The anticoagulant response to bishydroxycoumarin. II. The effect of D-thyroxine, clofibrate, and norethandrolone. Clin Pharmacol Ther 1967; 8:70-77. DOI
- Lorentz SM & Weibert RT: Potentiation of warfarin anticoagulation by topical testosterone ointment. Clin Pharm 1985; 4:332-334.
- Robinson BH, Hawkins JB, Ellis JE, et al: Decreased anticoagulant tolerance with oxymetholone. Lancet 1971; 1:1356. PubMed
- Longridge RG, Gillam PM, & Barton GM: Decreased anticoagulant tolerance with oxymetholone. Lancet 1971; 2:90. DOI
- Edwards MS & Curtis JR: Decreased anticoagulant tolerance with oxymetholone. Lancet 1971; 2:221. PubMed
- Goulbourne IA & Macleod DA: An interaction between danazol and warfarin. Case report. Br J Obstet Gynaecol 1981; 88:950-951. DOI
- Meeks ML, Mahaffey KW, & Katz MD: Danazol increases the anticoagulant effect of warfarin. Ann Pharmacother 1992; 26:641-642. DOI
Keep reading about Danazol
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:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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