Drug interactions
Efavirenz + Norethisterone
Severity: Moderate
Efavirenz and Norethisterone: 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 may lower progestin exposure and reduce hormonal contraceptive efficacy. Data for oral progestin products are limited, but contraceptive failure is a concern.
What this interaction means in plain words
Efavirenz and Norethisterone 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 belongs to Anti Virals; Norethisterone belongs to Endocrine.
Why it happens
Efavirenz induces CYP3A4, increasing norethisterone metabolism.
What to do
Advise an additional barrier method or an alternative non-oral contraceptive such as an IUD. Monitor for breakthrough bleeding.
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 Norethisterone
- Acitretin + Norethisterone Contraindicated
- Amobarbital + Norethisterone Major
- Apalutamide + Norethisterone Major
- Belzutifan + Norethisterone Major
- Bosentan + Norethisterone Major
- Brigatinib + Norethisterone Major
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 Norethisterone?
MediHelp rates the interaction as moderate. Efavirenz and Norethisterone 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 may lower progestin exposure and reduce hormonal contraceptive efficacy. Data for oral progestin products are limited, but contraceptive failure is a concern.
How serious is the interaction between Efavirenz and Norethisterone?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Advise an additional barrier method or an alternative non-oral contraceptive such as an IUD. Monitor for breakthrough bleeding.
What other medicines interact with Norethisterone?
MediHelp also lists interactions of Norethisterone with, for example, Acitretin, Amobarbital, Apalutamide. The full list is on the Norethisterone page.
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