Myfembree is not birth control. Despite containing hormonal ingredients that can change your menstrual cycle and reduce or stop your periods, the FDA’s own patient information states plainly: “MYFEMBREE does not prevent pregnancy.” You need to use separate, non-hormonal contraception the entire time you take it and for at least one week after stopping.
What Myfembree Is Actually For
Myfembree is a prescription medication approved for two specific conditions in premenopausal women: heavy menstrual bleeding caused by uterine fibroids (approved May 2021) and moderate to severe pain from endometriosis (approved August 2022). Each daily tablet contains three active ingredients: relugolix (40 mg), estradiol (1 mg), and norethindrone acetate (0.5 mg).
The main ingredient, relugolix, works by blocking a hormone signal in the brain that triggers your ovaries to produce estrogen and progesterone. This suppresses the hormonal environment that drives fibroid-related bleeding and endometriosis pain. The small amounts of estradiol and norethindrone acetate are added back to prevent the side effects of extremely low estrogen, like bone loss and hot flashes, not to act as contraception.
Why It’s Confused With Birth Control
The confusion makes sense. Myfembree contains norethindrone acetate, a synthetic progestin found in several birth control pills. It also reduces or stops periods in many women who take it, which feels a lot like what hormonal contraceptives do. And the idea that a drug suppressing your reproductive hormones wouldn’t also prevent pregnancy seems counterintuitive.
But Myfembree was never tested or approved as a contraceptive. The doses and combination of ingredients are designed to manage symptoms, not to reliably prevent ovulation in the way birth control pills do. During the clinical trials, all participants were asked to use non-hormonal contraception, yet 11 women still became pregnant while taking relugolix (either alone or in the Myfembree combination). Four of those pregnancies resulted in live births. That alone tells you this drug cannot be relied on to prevent pregnancy.
Why You Can’t Use Hormonal Birth Control With It
Here’s where it gets tricky. Not only is Myfembree not birth control, but you also can’t take hormonal birth control alongside it. The FDA prescribing information is clear: avoid using estrogen-containing contraceptives (like the pill, the patch, or the ring) while on Myfembree. Adding more estrogen on top of the estradiol already in Myfembree raises the risk of estrogen-related side effects, including blood clots. It can also make Myfembree itself less effective at controlling your fibroid or endometriosis symptoms because extra estrogen counteracts the suppressive effect of relugolix.
That means your contraceptive options while on Myfembree are limited to non-hormonal methods: condoms, copper IUDs, spermicide, or diaphragms. Before starting treatment, your prescriber will confirm you’re not pregnant and have you stop any hormonal contraceptives you’re currently using.
Recognizing Pregnancy Can Be Harder on Myfembree
Because Myfembree commonly reduces or eliminates menstrual bleeding, a missed period loses its usefulness as an early pregnancy signal. The FDA flags this directly as a warning: changes in your bleeding pattern may reduce your ability to recognize pregnancy. If you’re sexually active and relying on non-hormonal contraception while taking Myfembree, staying alert to other early pregnancy signs (nausea, breast tenderness, fatigue) becomes more important. Myfembree is contraindicated in pregnancy, meaning it should not be taken if you are or become pregnant.
What Happens When You Stop Taking It
Fertility returns relatively quickly after discontinuing Myfembree. In clinical studies of women with fibroids, 100% of participants in one trial and 93% in another resumed their menstrual periods after stopping the drug. The average time from the last dose to the return of menstruation was about 30 to 36 days. In the endometriosis trials, roughly 84% of women resumed periods, with an average return time of 27 to 39 days depending on the study.
You still need non-hormonal contraception for at least one week after your final dose. After that, you can transition to whatever contraceptive method you and your provider choose, including hormonal options if appropriate.
The Bottom Line on Myfembree and Pregnancy Prevention
Myfembree treats fibroid-related heavy bleeding and endometriosis pain. It is not a contraceptive, it was not studied as one, and pregnancies occurred during its clinical trials. You need a separate, non-hormonal birth control method for the entire duration of treatment and for one week after stopping. Hormonal birth control pills, patches, and rings should not be used at the same time because they interfere with how Myfembree works and increase the risk of side effects.