Drug interactions
Ethinyl estradiol-norgestimate + Warfarin
Severity: Major
Ethinyl estradiol-norgestimate and Warfarin: major interaction.
Last updated Sources: US FDA label
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 response, while some reports describe variable INR changes. Estrogens also carry their own thrombotic risk, which is undesirable in a patient needing anticoagulation.
What this interaction means in plain words
Ethinyl estradiol-norgestimate 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.
Ethinyl estradiol-norgestimate belongs to Endocrine; Warfarin belongs to Cardiovascular.
Why it happens
Pharmacodynamic opposition through increased clotting factor synthesis, with possible variable effects on warfarin metabolism.
What to do
Avoid estrogen-containing contraception in patients requiring anticoagulation where possible and choose a progestin-only or non-hormonal method. If used, monitor INR closely after 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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References
Other interactions of Ethinyl estradiol-norgestimate
- Ethinyl estradiol-norgestimate + Fezolinetant Contraindicated
- Ethinyl estradiol-norgestimate + Ombitasvir / paritaprevir / ritonavir and dasabuvir Contraindicated
- Ethinyl estradiol-norgestimate + Tranexamic acid Contraindicated
- Aminocaproic acid + Ethinyl estradiol-norgestimate Major
- Amobarbital + Ethinyl estradiol-norgestimate Major
- Anastrozole + Ethinyl estradiol-norgestimate Major
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 Ethinyl estradiol-norgestimate with Warfarin?
MediHelp rates the interaction as major. Ethinyl estradiol-norgestimate 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 response, while some reports describe variable INR changes. Estrogens also carry their own thrombotic risk, which is undesirable in a patient needing anticoagulation.
How serious is the interaction between Ethinyl estradiol-norgestimate 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: Avoid estrogen-containing contraception in patients requiring anticoagulation where possible and choose a progestin-only or non-hormonal method. If used, monitor INR closely after starting or stopping.
What other medicines interact with Ethinyl estradiol-norgestimate?
MediHelp also lists interactions of Ethinyl estradiol-norgestimate with, for example, Fezolinetant, Ombitasvir / paritaprevir / ritonavir and dasabuvir, Tranexamic acid. The full list is on the Ethinyl estradiol-norgestimate page.
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