Drug interactions
Fluoxymesterone + Warfarin
Severity: Major
Fluoxymesterone and Warfarin: major interaction.
Last updated Sources: UK SmPC
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Anabolic and androgenic steroids such as fluoxymesterone enhance warfarin's effect, raising INR and bleeding risk, sometimes substantially.
What this interaction means in plain words
Fluoxymesterone and Warfarin can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Why it happens
Androgens alter clotting factor synthesis and catabolism and may reduce warfarin clearance, increasing anticoagulant sensitivity.
What to do
Monitor INR closely when starting or stopping the androgen and reduce warfarin dose as required. Watch for bleeding.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
- Marevan 0.5mg Tablets - SmPC sections 4.3/4.5 (class statement: anabolic steroids; "anabolic steroids, cimetidine, clofibrate, chloramphenicol") — electronic medicines compendium (UK SmPC)
Other interactions of Warfarin
- Defibrotide + Warfarin Contraindicated
- Ketorolac + Warfarin Contraindicated
- Abciximab + Warfarin Major
- Acetylsalicylic acid + Warfarin Major
- Adagrasib + Warfarin Major
- Amiodarone + Warfarin Major
Frequently asked questions
Can I take Fluoxymesterone with Warfarin?
MediHelp rates the interaction as major. Fluoxymesterone and Warfarin can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Anabolic and androgenic steroids such as fluoxymesterone enhance warfarin's effect, raising INR and bleeding risk, sometimes substantially.
How serious is the interaction between Fluoxymesterone and Warfarin?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor INR closely when starting or stopping the androgen and reduce warfarin dose as required. Watch for bleeding.
What other medicines interact with Warfarin?
MediHelp also lists interactions of Warfarin with, for example, Defibrotide, Ketorolac, Abciximab. The full list is on the Warfarin page.
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