Drug interactions
Efavirenz + Norethindrone
Severity: Major
Efavirenz and Norethindrone: major 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 reduce progestin exposure, which can compromise the contraceptive efficacy of norethindrone-containing products. Unintended pregnancy is the main concern.
What this interaction means in plain words
Efavirenz and Norethindrone 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.
Why it happens
Efavirenz induces CYP3A4 and other enzymes, accelerating metabolism of norethindrone.
What to do
Advise an additional or alternative reliable contraceptive method such as an intrauterine device or barrier method. Do not rely on progestin-only pills alone during efavirenz therapy.
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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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 Norethindrone?
MediHelp rates the interaction as major. Efavirenz and Norethindrone 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. Efavirenz may reduce progestin exposure, which can compromise the contraceptive efficacy of norethindrone-containing products. Unintended pregnancy is the main concern.
How serious is the interaction between Efavirenz and Norethindrone?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Advise an additional or alternative reliable contraceptive method such as an intrauterine device or barrier method. Do not rely on progestin-only pills alone during efavirenz therapy.
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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