Carbamazepine and Etonogestrel and ethinyl estradiol interaction
Carbamazepine 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 Carbamazepine (EQUETRO) label · effective 2025-08-19
EQUETRO can reduce the effectiveness of hormonal contraceptives.
Equetro may decrease the effectiveness of hormonal contraceptives.
EQUETRO decreases the concentrations of the following drugs through induction of their metabolism: Hormonal Contraceptives (CYP3A4 Substrates) EQUETRO is a strong inducer of CYP3A4.
EQUETRO can increase the metabolism of certain hormonal contraceptives (through CYP3A4 induction) such as oral and subdermal implant contraceptives, leading to significantly lower plasma concentrations of hormones.
Cytochrome (CYP) 3A4 inhibitors, epoxide hydrolase inhibitors, CYP3A4 inducers, drugs metabolized by CYP1A2 or CYP3A4 (oral contraceptives, delavirdine, nefazodone), phenytoin, CNS depressants, lithium, chloroquine, mefloquine ( 7.1 , 7.2 , 7.3 )
From the Etonogestrel and ethinyl estradiol (Etonogestrel/Ethinyl Estradiol) label · effective 2025-02-26
Some drugs or herbal products that may decrease the effectiveness of hormonal contraceptives include: phenytoin, barbiturates, carbamazepine, bosentan, felbamate, griseofulvin, oxcarbazepine, rifampicin, topiramate, rifabutin, rufinamide, aprepitant, and products containing St.
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.
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.