Hormonal Contraceptive Agents/Efavirenz; Nevirapine Interactions
This information is generalized and not intended as specific medical advice. Consult your healthcare professional before taking or discontinuing any drug or commencing any course of treatment.
Medical warning:
Serious. These medicines may interact and cause very harmful effects. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.
How the interaction occurs:
Efavirenz and nevirapine may speed up how quickly your liver processes your hormonal contraceptive agent.
What might happen:
The blood levels of your contraceptive agent may decrease, causing breakthrough bleeding, spotting, or pregnancy.
What you should do about this interaction:
Contact your healthcare professionals (e.g. doctor or pharmacist) as soon as possible about taking these two medicines together. You should use another form of birth control in addition to your hormonal contraceptive agent while you are taking efavirenz or nevirapine. Because efavirenz stays in your body a long time, you should continue to use another form of birth control with your hormonal contraceptive for 12 weeks after you stop taking efavirenz.Emergency contraceptives may be less effective also. You may need a larger dose than normal. Discuss the dose and the need to confirm that you do not become pregnant with a pregnancy test with your healthcare professional.Your healthcare professionals may be aware of this interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.
- 1.Sustiva (efavirenz) US prescribing information. Bristol-Myers Squibb Company November, 2023.
- 2.Viramune (nevirapine) US prescribing information. Boehringer Ingelheim Pharmaceuticals, Inc. June, 2022.
- 3.Mildvan D, Yarrish R, Marshak A, Hutman HW, McDonough M, Lamson M, Robinson P. Pharmacokinetic interaction between nevirapine and ethinyl estradiol/norethindrone when administered concurrently to HIV-infected women. J Acquir Immune Defic Syndr 2002 Apr 15;29(5):471-7.
- 4.Medicines and Healthcare products Regulatory Agency. Levonorgestrel-containing emergency hormonal contraception: advice on interactions with hepatic enzyme inducers and contraceptive efficacy. available at: https://www.gov.uk/drug-safety-update/levonorgestrel-containing-emergency- hormonal-contraception-advice-on-interactions-with-hepatic-enzyme-inducers -and-contraceptive-efficacy September 15, 2016..
- 5.Scarsi KK, Smeaton LM, Podany AT, Olefsky M, Woolley E, Barr E, Pham M, Mawlana S, Supparatpinyo K, Gatechompol S, Jalil EM, Gadama L, Badal-Faesen S, Belaunzaran-Zamudio PF, Godfrey C, etal. Pharmacokinetics of dose-adjusted levonorgestrel emergency contraception combined with efavirenz-based antiretroviral therapy or rifampicin-containing tuberculosis regimens. Contraception 2023 Jan 12;109951.
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CONDITIONS OF USE: The information in this database is intended to supplement, not substitute for, the expertise and judgment of healthcare professionals. The information is not intended to cover all possible uses, directions, precautions, drug interactions or adverse effects, nor should it be construed to indicate that use of a particular drug is safe, appropriate or effective for you or anyone else. A healthcare professional should be consulted before taking any drug, changing any diet or commencing or discontinuing any course of treatment.