Efavirenz, lamivudine, and tenofovir and Norelgestromin and ethinyl estradiol interaction
Efavirenz, lamivudine, and tenofovir and Norelgestromin 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 Norelgestromin and ethinyl estradiol label · effective 2026-04-16
CYP3A4 inhibitors such as itraconazole, voriconazole, fluconazole, grapefruit juice, or ketoconazole may increase plasma hormone concentrations.
Counsel patients to use a back-up or alternative method of contraception when enzyme inducers are used with CHCs.
Counsel women to use an alternative method of contraception or a back-up method when enzyme inducers are used with CHCs, 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.
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.