Relugolix Side Effects in Fibroids, Endometriosis May Be Minimal

Jaleesa Baulkman

October 21, 2021

Side effects from relugolix combination therapy (Myfembree) in premenopausal women treated for uterine fibroids and endometriosis are minimal, according to research presented at the American Society for Reproductive Medicine's 2021 meeting.

The Food and Drug Administration approved relugolix, a daily oral gonadotropin-releasing hormone antagonist medication, earlier this year to treat heavy menstrual bleeding associated with uterine fibroids. It has not received Food and Drug Administration approval to treat endometriosis yet.

"It was a good kind of vindication about the safety of relugolix combination therapy," Ayman Al-Hendy, MD, PhD, gynecologist and endoscopic surgeon at the University of Chicago, said in an interview.

Researchers led by Al-Hendy analyzed the results from two 24-week clinical trials that examined the effects of relugolix on premenopausal women between the ages of 18 and 50 suffering from uterine fibroids and endometriosis, both of which found that the treatment was well tolerated. With 1,344 patients in total, researchers found that the most common side effects of the treatment were headache, which occurred in 24.3% of participants, and hot flush, which affected 10.6%.

However, the prevalence of adverse reactions was similar to that of the placebo group in which 21.4% of participants experienced headaches and 6.4% experienced hot flushes, which, according to Al-Hendy, means that there is "really no increased risk" of experiencing an adverse event while taking relugolix.

"If we follow a large number of patients [with uterine fibroids or endometriosis], they will have some of these symptoms like headache or hot flushes or fatigue and so on. Either because it just happens in women for no known reason or because maybe the disease itself is causing some of these symptoms. The question is does the treatment in this case increase the frequency of these events?" Al-Hendy said.

"As long as it's similar, fairly similar, or close between the [treatment and placebo group], then we know it's not because of the medication," Al-Hendy added.

Other adverse reactions that occurred while taking relugolix were "relatively rare" Al-Hendy said during his presentation. About 5.5% of those who took relugolix had uterine bleeding, 3.4% had decreased libido, 1.9% suffered from hyperhidrosis, 1.2% experienced night sweats, and 1.3% suffered from vaginal dryness.

The study shows that the risk profile of relugolix combination therapy is favorable and the side effects are relatively mild compared with past treatment options used to treat fibroids or endometriosis, said J. Ricardo Loret de Mola, MD, FACOG, FACS, who was not involved in the study.

However, Loret de Mola emphasized that this treatment isn't for women who are seeking fertility or to get pregnant so it's important for physicians to ask patients about their goals for treatment. Relugolix treatment could be a way for fibroid patients in their reproductive age to buy time and reduce the number of surgeries needed to get them to "the point where they would be ready to become mothers."

He said surgery could be the right option for endometriosis patients who want to have children in the near future.

"This is an additional tool that we have available now that's effective," Loret de Mola said. "It is not going to cure either one of the two conditions, but could buy enough time for patients to be able to reach their goals, which is not having symptoms of endometriosis and fibroids after menopause or for people who just want to buy time."

Al-Hendy said he hopes his findings reassure and encourage health care providers to discuss with patients different options for treating fibroids, and not just counsel them about surgery.

"So more awareness of these nonsurgical options hopefully will offer our patients a wide range of options when they seek help with fibroids and then against endometriosis [if or when] it's [FDA]-approved," Al-Hendy said.

None of the experts interviewed had conflicts of interest.

This article originally appeared on, part of the Medscape Professional Network.


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