Efavirenz, lamivudine, and tenofovir and Etonogestrel and ethinyl estradiol interaction
Efavirenz, lamivudine, and tenofovir and Etonogestrel 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 Etonogestrel and ethinyl estradiol (Etonogestrel/Ethinyl Estradiol) label · effective 2025-02-26
…ritonavir, darunavir/ritonavir, (fos)amprenavir/ritonavir, lopinavir/ritonavir, and tipranavir/ritonavir] or increase [e.g., indinavir and atazanavir/ritonavir]) /HCV protease inhibitors (decrease [e.g., boceprevir and telaprevir]) or with non-nucleoside reverse transcriptase inhibitors (decrease [e.g., efavirenz, nevirapine] or increase [e.g., etravirine]).
Concomitant administration of strong or moderate CYP3A4 inhibitors such as itraconazole, voriconazole, fluconazole, grapefruit juice, or ketoconazole may increase plasma estrogen and/or progestin 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 non-hormonal method of contraception or a back-up method when enzyme inducers are used with Etonogestrel/Ethinyl Estradiol Vaginal Ring, and to continue back-up non-hormonal 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
Decreased exposure of etonogestrel may be expected.
There have been postmarketing reports of contraceptive failure with etonogestrel in EFV-exposed patients.
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.