Drug interactions
Levonorgestrel oral / ethinylestradiol / ferrous bisglycinate + Warfarin
Severity: Major
Levonorgestrel oral / ethinylestradiol / ferrous bisglycinate and Warfarin: major interaction.
Last updated
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
Estrogen-containing contraceptives raise clotting factor levels and can reduce warfarin's effect, while some reports show variable INR changes. They also increase thrombotic risk, which is a concern in patients needing anticoagulation.
What this interaction means in plain words
Levonorgestrel oral / ethinylestradiol / ferrous bisglycinate 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
Ethinylestradiol increases hepatic synthesis of clotting factors, opposing warfarin, and may also alter warfarin metabolism.
What to do
Generally avoid estrogen-containing contraceptives in patients needing anticoagulation for thrombosis and consider progestin-only or non-hormonal methods. If used, monitor INR closely when starting or stopping.
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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Frequently asked questions
Can I take Levonorgestrel oral / ethinylestradiol / ferrous bisglycinate with Warfarin?
MediHelp rates the interaction as major. Levonorgestrel oral / ethinylestradiol / ferrous bisglycinate 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. Estrogen-containing contraceptives raise clotting factor levels and can reduce warfarin's effect, while some reports show variable INR changes. They also increase thrombotic risk, which is a concern in patients needing anticoagulation.
How serious is the interaction between Levonorgestrel oral / ethinylestradiol / ferrous bisglycinate 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: Generally avoid estrogen-containing contraceptives in patients needing anticoagulation for thrombosis and consider progestin-only or non-hormonal methods. If used, monitor INR closely when starting or stopping.
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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