Drug interactions
Levonorgestrel + Phenindione
Severity: Moderate
Levonorgestrel and Phenindione: moderate 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
Phenindione is an anticoagulant, whereas hormonal contraceptives can promote thrombosis, so the two have opposing effects. Anticoagulant control may be altered, and thrombotic risk is a concern with systemic progestins; an intrauterine system has minimal systemic exposure.
What this interaction means in plain words
Levonorgestrel and Phenindione can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Why it happens
Pharmacodynamic opposition between prothrombotic hormonal effects and vitamin K antagonist anticoagulation.
What to do
Monitor INR or clotting parameters when starting or stopping the hormonal product. A levonorgestrel intrauterine system is preferred over systemic hormonal methods.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Levonorgestrel
Frequently asked questions
Can I take Levonorgestrel with Phenindione?
MediHelp rates the interaction as moderate. Levonorgestrel and Phenindione can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Phenindione is an anticoagulant, whereas hormonal contraceptives can promote thrombosis, so the two have opposing effects. Anticoagulant control may be altered, and thrombotic risk is a concern with systemic progestins; an intrauterine system has minimal systemic exposure.
How serious is the interaction between Levonorgestrel and Phenindione?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor INR or clotting parameters when starting or stopping the hormonal product. A levonorgestrel intrauterine system is preferred over systemic hormonal methods.
What other medicines interact with Levonorgestrel?
MediHelp also lists interactions of Levonorgestrel with, for example, Amobarbital, Apalutamide, Belzutifan. The full list is on the Levonorgestrel page.
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