Drug Interaction Report

Oxandrolone and Dicumarol: Interaction Details

A pharmacist-reviewed analysis of the Oxandrolone and Dicumarol interaction: the documented clinical effects, severity rating, onset, mechanism, and management considerations, with cited references throughout.

AI-assisted, pharmacist-reviewed · Source data updated Aug 9, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature

Oxandrolone

Oxandrin Oxandrin®
+

Dicumarol

No brand names on record
Dr. Brian Staiger, PharmD, BCPS
Medically reviewed by
Dr. Brian Staiger, PharmD, BCPS
Updated Aug 9, 2026
Editorial policy · Data sources
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Interaction severity
Major
Potentially serious — often needs a change or close monitoring.
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.

Of 20 documented Oxandrolone interactions, 17 are rated major — including this one.
Worried about symptoms right now? Contact your pharmacist or prescriber, or call Poison Control at 1-800-222-1222 (US). Call 911 for an emergency.
Onset
delayed
Evidence
probable
Severity
Major

What happens

Increased anticoagulant response and increased risk of bleeding

Interaction Deep Dive

Anabolic steroids may increase the anticoagulant response to oral anticoagulants, such as dicumarol7. In a multi-dose study of healthy subjects (n=15), concurrent treatment with warfarin (a related coumarin anticoagulant) and oxandrolone produced clinically significant increases in the mean half-life and area under the concentration-time curve (AUC) of the isomeric metabolites of warfarin; this required substantial reductions in warfarin dose in order to maintain a therapeutic target level (1.5) in International Normalized Ratio values 8. A number of case reports have demonstrated that coadministration of oral anticoagulants and 17-alkylated androgens (oxandrolone, fluoxymesterone, oxymetholone, methyltestosterone, methandrostenolone, stanozolol) has resulted in a prolonged prothrombin time and hemorrhages 23451.

Why it happens (mechanism)

Unknown

Literature reports

2 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 (oxandrolone, fluoxymesterone, oxymetholone, methyltestosterone, methandrostenolone, stanozolol) appear to be more likely to induce this reaction than the non-substituted steroids 12345.

b) Concurrent treatment with warfarin (a coumarin anticoagulant) and oxandrolone produced clinically significant increases in the mean half-life and area under the concentration-time curve (AUC) of the isomeric metabolites of warfarin. In a multidose study, healthy subjects (n=15) received concomitant treatment with oxandrolone 5 or 10 milligrams (mg) twice daily and warfarin (mean daily dose of 6.13 mg). For S-warfarin, the mean half-life increased from 26 to 48 hours and AUC increased from 4.55 nanograms x hour/milliliter (ng x hr/mL) to 12.08 ng x hr/mL); similar increases were observed for the R-warfarin isomer (actual values not available). Microscopic hematuria was confirmed in 9 patients, and 1 patient exhibited gingival bleeding. A 5.5-fold decrease in mean daily warfarin dose was required (from 6.13 mg/day to 1.13 mg/day) in order to maintain a target International Normalization Ratio of 1.5 6.

Common questions

Can I take Oxandrolone and Dicumarol together?

Increased anticoagulant response and increased risk of bleeding Always confirm with your pharmacist or prescriber before making any change.

How serious is the Oxandrolone and Dicumarol 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 Oxandrolone or Dicumarol 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 (8)

  1. 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. PubMed
  2. Lorentz SM & Weibert RT: Potentiation of warfarin anticoagulation by topical testosterone ointment. Clin Pharm 1985; 4:332-334.
  3. Robinson BH, Hawkins JB, Ellis JE, et al: Decreased anticoagulant tolerance with oxymetholone. Lancet 1971; 1:1356. PubMed
  4. Longridge RG, Gillam PM, & Barton GM: Decreased anticoagulant tolerance with oxymetholone. Lancet 1971; 2:90. PubMed
  5. Edwards MS & Curtis JR: Decreased anticoagulant tolerance with oxymetholone. Lancet 1971; 2:221. PubMed
  6. Product Information: Oxandrin(R), oxandrolone, USP. Savient Pharmaceuticals, Inc. 1 Tower Center, 14th Floor, East Brunswick, NJ, 2003. DailyMed
  7. Product Information: Oxandrin(TM), oxandrolone. G.D. Searle & Co. Chicago, IL, 1998. DailyMed
  8. Product Information: Oxandrin(R), oxandrolone, USP. Savient Pharmaceuticals, Inc. 1 Tower Center, 14th Floor, East Brunswick, NJ, 2003. DailyMed
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Oxandrolone

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All Oxandrolone interactions (20) Oxandrolone drug information
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Dicumarol

Keep reading about Dicumarol

All Dicumarol interactions (61)
Also serious with: Amoxicillin Aspirin Aspirin Rectal Danazol
Beyond drug–drug

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:

Oxandrolone + Activated Charcoal Coffee Charcoal European Mandrake Glucomannan Guar Gum Gum Arabic Slippery Elm Tragacanth + 9 more
Dicumarol + Activated Charcoal Danshen Piracetam Aconite Allspice Aloe Alpha-lipoic Acid Andrographis + 210 more

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This information is for education, not a substitute for professional medical advice. Do not start, stop, or change any medication without talking to your pharmacist or prescriber.