Drug interactions
Efavirenz + Ethinylestradiol
Severity: Moderate
Efavirenz and Ethinylestradiol: 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
Efavirenz can change ethinylestradiol exposure and may reduce the reliability of hormonal contraception. Unintended pregnancy is a concern, and efavirenz is also teratogenic risk-relevant.
What this interaction means in plain words
Efavirenz and Ethinylestradiol 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
Efavirenz induces CYP3A4 and other enzymes involved in estrogen and progestin metabolism, potentially lowering contraceptive hormone exposure.
What to do
Recommend a reliable barrier method alongside hormonal contraception or use a non-hormonal method such as a copper IUD. Review contraceptive choice at each visit.
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 Efavirenz
- Cobimetinib + Efavirenz Contraindicated
- Dienogest / estradiol valerate + Efavirenz Contraindicated
- Dihydroergotamine intranasal + Efavirenz Contraindicated
- Dihydroergotamine + Efavirenz Contraindicated
- Doravirine + Efavirenz Contraindicated
- Efavirenz + Elbasvir / grazoprevir Contraindicated
Frequently asked questions
Can I take Efavirenz with Ethinylestradiol?
MediHelp rates the interaction as moderate. Efavirenz and Ethinylestradiol 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. Efavirenz can change ethinylestradiol exposure and may reduce the reliability of hormonal contraception. Unintended pregnancy is a concern, and efavirenz is also teratogenic risk-relevant.
How serious is the interaction between Efavirenz and Ethinylestradiol?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Recommend a reliable barrier method alongside hormonal contraception or use a non-hormonal method such as a copper IUD. Review contraceptive choice at each visit.
What other medicines interact with Efavirenz?
MediHelp also lists interactions of Efavirenz with, for example, Cobimetinib, Dienogest / estradiol valerate, Dihydroergotamine intranasal. The full list is on the Efavirenz page.
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