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How Myfembree Treats Symptoms Associated With Uterine Fibroids

Myfembree is a once-daily pill approved by the FDA to treat heavy menstrual bleeding caused by uterine fibroids in premenopausal women. In clinical trials, it substantially reduced heavy bleeding compared with placebo.

By Dr. David Howard, MD, PhD, FACOGPublished February 27, 2024Updated September 2026Leiomyoma (AUB-L)

In the two main clinical trials, about 7 in 10 women taking Myfembree met the goal of much lighter bleeding after six months, compared with fewer than 2 in 10 taking a placebo. On average, menstrual blood loss fell by roughly 80% from where it started.

Here is how Myfembree works, who it is for, and what to know before taking it.

Who is Myfembree prescribed for?

Myfembree is a once-daily tablet containing relugolix, estradiol, and norethindrone acetate. It can be taken with or without food. It has two FDA-approved uses:

  • Heavy menstrual bleeding caused by uterine fibroids, in premenopausal women
  • Moderate to severe pain caused by endometriosis

For fibroids, the approved use is heavy bleeding. It is not approved to treat fibroid-related pain or pressure.

How does Myfembree work?

Each tablet contains three medicines with different jobs.

Relugolix

Relugolix is a gonadotropin-releasing hormone (GnRH) antagonist. It blocks GnRH receptors in the pituitary gland, at the base of the brain, which normally signal the ovaries to make estrogen and progesterone. With less of these hormones, the uterine lining stays thin and menstrual bleeding decreases sharply.

Estradiol

Adding estrogen to a medicine that lowers estrogen may seem contradictory. Estradiol, which is chemically identical to the estrogen the body makes, is included in a low dose as "add-back" therapy. It limits side effects of very low estrogen, especially bone loss and hot flashes.

Norethindrone acetate

Norethindrone acetate is a progestin, a medicine that acts like progesterone. Whenever estrogen is given to someone with a uterus, a progestin is included to protect the uterine lining, because estrogen alone raises the risk of endometrial hyperplasia and cancer.

Does Myfembree cure fibroids?

No. Myfembree reduces bleeding while you take it, but it does not meaningfully shrink fibroids and does not cure them. Its effects are reversible: menstrual bleeding typically returns after the medicine is stopped. It can be a good option to control bleeding, to build iron levels back up, or to bridge to menopause or a procedure.

Important safety information

  • Myfembree has a boxed warning for blood clots and vascular events, such as stroke and heart attack. It should not be used by women at high risk of these, including women over 35 who smoke.
  • Treatment is limited to 24 months because of bone density loss.
  • It should not be used by women with osteoporosis, known or suspected breast or other hormone-sensitive cancer, significant liver disease, or abnormal uterine bleeding that has not been evaluated.
  • It can make pregnancy harder to recognize. Use non-hormonal contraception during treatment and for one week after stopping.
  • Mood changes, including depression, and changes in liver tests have been reported.

This is not the complete safety information. Review the full prescribing information with your clinician.

The bottom line

Myfembree is an effective option for heavy menstrual bleeding caused by fibroids. Through its combination of relugolix, estradiol, and norethindrone acetate, it reduces bleeding while limiting the side effects of low estrogen. It does not shrink or cure fibroids, and it is not safe for everyone.

Your clinician will review your health history to decide whether Myfembree is right for you, and how it compares with other options such as tranexamic acid, the levonorgestrel IUD, or a procedure.

Sources

  1. MYFEMBREE (relugolix, estradiol, and norethindrone acetate) tablets. U.S. Prescribing Information. Current version.
  2. Al-Hendy A, Lukes AS, Poindexter AN, et al. Treatment of uterine fibroid symptoms with relugolix combination therapy. N Engl J Med. 2021;384(7):630–642.
  3. American College of Obstetricians and Gynecologists. Practice Bulletin No. 228: Management of symptomatic uterine leiomyomas. Obstet Gynecol. 2021;137(6):e100–e115.

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