Drug interactions
Efavirenz + Norgestrel
Severity: Major
Efavirenz and Norgestrel: 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 lower norgestrel concentrations, which could reduce the effectiveness of progestin-only contraception and raise the risk of unintended pregnancy.
What this interaction means in plain words
Efavirenz and Norgestrel 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 belongs to Anti Virals; Norgestrel belongs to Endocrine.
Why it happens
CYP3A4 induction by efavirenz increases progestin clearance.
What to do
Add a barrier method or switch to a non-hormonal or long-acting method such as an intrauterine device. Continue backup protection for about 28 days after stopping efavirenz.
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
Other interactions of Norgestrel
Frequently asked questions
Can I take Efavirenz with Norgestrel?
MediHelp rates the interaction as major. Efavirenz and Norgestrel 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 lower norgestrel concentrations, which could reduce the effectiveness of progestin-only contraception and raise the risk of unintended pregnancy.
How serious is the interaction between Efavirenz and Norgestrel?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Add a barrier method or switch to a non-hormonal or long-acting method such as an intrauterine device. Continue backup protection for about 28 days after stopping efavirenz.
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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