Drug interactions
Ethinyl estradiol-levonorgestrel + Fostemsavir
Severity: Moderate
Ethinyl estradiol-levonorgestrel and Fostemsavir: 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
Fostemsavir's active metabolite temsavir raises ethinyl estradiol concentrations. Higher estrogen exposure may increase estrogen-related adverse effects such as thromboembolic risk.
What this interaction means in plain words
Ethinyl estradiol-levonorgestrel and Fostemsavir 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.
Ethinyl estradiol-levonorgestrel belongs to Endocrine; Fostemsavir belongs to Anti Virals.
Why it happens
Temsavir inhibits BCRP, increasing ethinyl estradiol exposure.
What to do
Limit the ethinyl estradiol dose to no more than 30 mcg daily when combined with fostemsavir. Monitor for estrogen-related adverse effects and consider an alternative contraceptive in patients at thrombotic risk.
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 Ethinyl estradiol-levonorgestrel
- Ethinyl estradiol-levonorgestrel + Fezolinetant Contraindicated
- Ethinyl estradiol-levonorgestrel + Ombitasvir / paritaprevir / ritonavir and dasabuvir Contraindicated
- Ethinyl estradiol-levonorgestrel + Tranexamic acid Contraindicated
- Aminocaproic acid + Ethinyl estradiol-levonorgestrel Major
- Amobarbital + Ethinyl estradiol-levonorgestrel Major
- Anastrozole + Ethinyl estradiol-levonorgestrel Major
Other interactions of Fostemsavir
- Apalutamide + Fostemsavir Contraindicated
- Carbamazepine + Fostemsavir Contraindicated
- Enzalutamide + Fostemsavir Contraindicated
- Fostemsavir + Mitotane Contraindicated
- Fostemsavir + Phenytoin Contraindicated
- Fostemsavir + Rifampicin Contraindicated
Frequently asked questions
Can I take Ethinyl estradiol-levonorgestrel with Fostemsavir?
MediHelp rates the interaction as moderate. Ethinyl estradiol-levonorgestrel and Fostemsavir 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. Fostemsavir's active metabolite temsavir raises ethinyl estradiol concentrations. Higher estrogen exposure may increase estrogen-related adverse effects such as thromboembolic risk.
How serious is the interaction between Ethinyl estradiol-levonorgestrel and Fostemsavir?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Limit the ethinyl estradiol dose to no more than 30 mcg daily when combined with fostemsavir. Monitor for estrogen-related adverse effects and consider an alternative contraceptive in patients at thrombotic risk.
What other medicines interact with Ethinyl estradiol-levonorgestrel?
MediHelp also lists interactions of Ethinyl estradiol-levonorgestrel with, for example, Fezolinetant, Ombitasvir / paritaprevir / ritonavir and dasabuvir, Tranexamic acid. The full list is on the Ethinyl estradiol-levonorgestrel page.
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