Efavirenz, lamivudine, and tenofovir and Norgestrel and ethinyl estradiol interaction
Efavirenz, lamivudine, and tenofovir and Norgestrel and ethinyl estradiol: both prescribing labels describe an interaction that usually calls for monitoring, a dose change, or spacing the doses.
Usually manageable with monitoring or a dose change. Tell your pharmacist you take both.
What the FDA labels say
From the Norgestrel and ethinyl estradiol (Low-Ogestrel) label · effective 2025-07-28
Concomitant administration of CYP3A4 inhibitors such as itraconazole, fluconazole, grapefruit juice or ketoconazole may increase plasma hormone concentrations.
Counsel women to use an alternative method of contraception or a back-up method when enzyme inducers are used with COCs, and to continue back-up contraception for 28 days after discontinuing the enzyme inducer to ensure contraceptive reliability.
From the Efavirenz, lamivudine, and tenofovir (SYMFI) label · effective 2019-10-15
Hormonal contraceptives: Oral Ethinyl estradiol/ Norgestimate ↓ active metabolites of norgestimate A reliable method of barrier contraception should be used in addition to hormonal contraceptives.
Implant Etonogestrel ↓ etonogestrel A reliable method of barrier contraception should be used in addition to hormonal contraceptives.
There have been postmarketing reports of contraceptive failure with etonogestrel in EFV-exposed patients.
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.