Myfembree (relugolix/estradiol/norethindrone) is a brand-name medication prescribed to manage pain or heavy menstruation from some reproductive health conditions. As with other drugs, Myfembree can cause side effects, such as hot flashes.

Myfembree can cause certain side effects, some of which are more common than others. These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

These are just a few of the more common side effects reported by people who took Myfembree in clinical trials:

  • night sweats
  • hot flashes
  • low libido (low sex drive)
  • hair loss
  • irregular menstruation, such as lighter periods, shorter periods, or missed periods

Mild side effects can occur with Myfembree use. This list doesn’t include all possible mild side effects of the drug. For more information, you can refer to Myfembree’s prescribing information.

Myfembree may be prescribed to manage heavy periods caused by fibroids or to manage pain caused by endometriosis.

Mild side effects that have been reported in the drug’s clinical trials include:

These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. If you develop a side effect while taking Myfembree and want to tell the FDA about it, visit MedWatch.

* An allergic reaction is possible after taking Myfembree. To learn more, see the “Side effect specifics” section below.

Myfembree may cause serious side effects. The list below may not include all possible serious side effects of the drug. For more information, you can refer to Myfembree’s prescribing information.

If you develop serious side effects while taking Myfembree, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Serious side effects that have been reported and their symptoms include:

* For more information about this side effect, see “Side effect specifics” below.
† Myfembree has a boxed warning for this side effect. This is the most serious warning from the FDA. To learn more, see the “Side effect specifics” section below.
‡ An allergic reaction is possible after taking Myfembree. To learn more, see the “Side effect specifics” section below.

Myfembree may cause several side effects. Here are some frequently asked questions about the drug’s side effects and their answers.

Can Myfembree cause weight loss or weight gain?

No, Myfembree is not expected to cause weight changes. Neither weight loss nor weight gain was reported in clinical trials of the drug.

However, Myfembree may cause an irregular menstrual cycle, including missed periods. In some cases, you may experience no periods at all during treatment. Missing a period is also one of the earliest signs of pregnancy. If you regularly miss periods because of Myfembree, it may be more difficult to know if you become pregnant during treatment.

However, weight gain can be a sign of pregnancy, in addition to nausea and breast tenderness. If you’re engaging in sexual activity that could lead to pregnancy and you notice any unexplained weight gain, talk with your doctor right away.

Does Myfembree cause long-term side effects?

Yes, it’s possible for Myfembree to cause long-term side effects.

Myfembree can cause a loss of bone density, which is a serious condition that cannot be reversed. To help prevent this side effect, your doctor won’t prescribe Myfembree for longer than 2 years. However, if you currently have osteoporosis, your doctor likely won’t prescribe Myfembree at all.

Myfembree also has a boxed warning about the risk of blood clots, which can happen at any time during treatment. Blood clots can lead to serious cardiovascular problems such as heart attack or stroke. These problems could require long-term treatment or recovery time. To learn more, see “Side effect specifics” just below.

Learn more about some of the side effects that Myfembree may cause. To find out how often side effects occurred in clinical trials, see the prescribing information for Myfembree.

Risk of blood clots and blood vessel disorders

Myfembree has a boxed warning about the increased risk of blood clots and blood vessel disorders. This is the most serious warning from the FDA. A boxed warning alerts healthcare professionals and patients to the most serious side effects a drug may cause.

Drugs that contain estrogen and progestin, including Myfembree, have been shown to increase the risk of blood clots and serious cardiovascular problems. Specifically, deep vein thrombosis and pulmonary embolism have been reported with estrogen and progestin drugs. These blood clots can lead to serious cardiovascular problems such as heart attack or stroke.

Symptoms of a blood clot can include:

  • persistent arm or leg pain
  • pain, warmth, or swelling in your arm or leg
  • dizziness
  • sharp chest pain
  • shortness of breath

You may have a higher risk of this side effect if you’ve previously had a heart problem or if you have certain risk factors for heart problems, such as smoking, obesity, or high blood pressure. The risk of a blood clot may increase further in people ages 35 years or older who have these risk factors.

What you can do

Talk with your doctor about your blood clot risk factors before starting treatment with Myfembree. If you’ve had blood clots in the past or are older than age 35 years and you smoke cigarettes, your doctor will recommend other treatment options for you.

Mood changes

It’s possible for Myfembree to cause serious mood changes, such as depression or anxiety. In the drug’s clinical trials, mood or behavioral changes were commonly reported.

Symptoms of mood changes include:

What you can do

You may have a higher risk of mood changes if you’ve ever had depression or another mood disorder. Before you start taking Myfembree, talk with your doctor about your mental health history. They will likely monitor your condition closely for signs of depression or other mood changes during treatment with Myfembree.

If you notice any new or worsening symptoms of depression, anxiety, or suicidal thoughts, tell your doctor right away.

Allergic reaction

As with most drugs, Myfembree can cause an allergic reaction in some people. It’s not clear how often this side effect occurred in the drug’s clinical trials.

Symptoms can be mild or serious and can include:

  • skin rash
  • itching
  • flushing
  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What you can do

For mild symptoms of an allergic reaction, call your doctor right away. They may recommend ways to ease your symptoms and determine whether you should keep taking Myfembree. However, if your symptoms are serious and you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Suicide prevention

If you know someone at immediate risk of self-harm, suicide, or hurting another person:

  • Ask the tough question: “Are you considering suicide?”
  • Listen to the person without judgment.
  • Call 911 or the local emergency number, or text TALK to 741741 to communicate with a trained crisis counselor.
  • Stay with the person until professional help arrives.
  • Try to remove any weapons, medications, or other potentially harmful objects if it’s safe to do so.

If you or someone you know is having thoughts of suicide, a prevention hotline can help. The 988 Suicide and Crisis Lifeline is available 24 hours a day at 988. During a crisis, people who are hard of hearing can use their preferred relay service or dial 711 then 988.

Find more links and local resources.

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This drug comes with several precautions. Below is important information you should consider before taking Myfembree.

Boxed warning: Risk of blood clots and blood vessel disorders

This drug has a boxed warning for the risk of blood clots and blood vessel disorders. This is the most serious warning from the FDA. For details, see the “Side effect specifics” section above.

Other precautions

Be sure to talk with your doctor about your health history before you take Myfembree. This drug may not be the right treatment for you if you have certain medical conditions or other factors that affect your health. These include:

Depression or other mood disorders: Myfembree can cause mood changes such as depression, anxiety, or suicidal thoughts in some people. If you currently have a mental health condition affecting your mood, it’s possible that taking Myfembree could worsen it. Talk with your doctor about your mental health history before you start taking Myfembree.

High blood pressure: Myfembree can cause high blood pressure. If you already have this condition, taking Myfembree could cause your blood pressure to become dangerously high. High blood pressure may also increase the risk of serious heart problems such as blood clots, heart attack, or stroke. If you have high blood pressure, your doctor may monitor your blood pressure more closely during treatment with Myfembree or recommend a different treatment option for you.

Osteoporosis: Myfembree can cause a loss of bone density. Over time, this can develop into osteoporosis. If you already have this condition or certain risk factors for it, your doctor will likely not prescribe Myfembree. Talk with your doctor about other treatment options for you.

Hormone-sensitive cancer: Before starting treatment with Myfembree, tell your doctor whether you’ve ever had breast cancer or another type of cancer that’s sensitive to hormones. Certain types of cancer rely on estrogen to develop and grow. Because Myfembree contains a form of estrogen, taking it may worsen your cancer or increase the risk of recurrence. If you have this type of cancer or have previously had it, your doctor will likely not prescribe Myfembree. However, they can recommend another treatment option for you.

Diabetes: Treatment with Myfembree can cause high blood sugar. If you have diabetes, your doctor will monitor your blood sugar levels more frequently. They can also show you how to monitor your blood sugar at home. If necessary, they may adjust your diabetes medication to help manage your blood sugar levels while you take Myfembree.

Lipid disorders: Taking Myfembree can increase the levels of cholesterol and triglycerides in your blood. If you already have high cholesterol, taking Myfembree can worsen your condition. Having a lipid disorder may increase your risk of a heart problem such as a blood clot, heart attack, or stroke. If you have a lipid disorder, your doctor will monitor your cholesterol closely during treatment with Myfembree.

Unexplained vaginal bleeding: Before you start taking Myfembree, tell your doctor about any unexplained vaginal bleeding you’ve experienced. Your doctor will likely want to determine the cause of this bleeding and treat it before prescribing Myfembree. In some cases, they may not prescribe this drug if you have unexplained vaginal bleeding.

Liver problems: Treatment with Myfembree may lead to liver damage. If you have liver disease, taking Myfembree can worsen your condition. Before you start treatment, tell your doctor if you have a liver condition. They will likely not prescribe Myfembree, but they can recommend a safer treatment option for you.

Gallbladder problems: Taking Myfembree may increase your risk of developing a gallbladder disease. If you’ve ever had a gallbladder problem such as gallstones or cholestasis of pregnancy, talk with your doctor. They’ll let you know whether Myfembree is safe for you to take.

Allergic reaction: If you’ve had an allergic reaction to Myfembree or any of its ingredients, your doctor will likely not prescribe Myfembree. Ask your doctor what other medications may be better options for you.

Pregnancy and breastfeeding: If you’re pregnant, Myfembree is not safe for you to take. This drug and its active ingredients have been associated with early pregnancy loss. If you’re engaging in sexual activity that could lead to pregnancy, talk with your doctor before you start taking Myfembree. They’ll likely recommend using effective nonhormonal birth control during treatment and for 1 week after stopping.

If you become pregnant while taking Myfembree, talk with your doctor right away. They’ll have you stop taking the drug. In addition, you may wish to consider joining the drug’s pregnancy registry. The purpose of the pregnancy registry is to monitor outcomes and side effects of people exposed to Myfembree during pregnancy. To learn more, you or your doctor can call 855-428-0707.

In addition, it’s not known whether Myfembree is safe for you to take while breastfeeding. If you’re breastfeeding or planning to do so, talk with your doctor before you start taking Myfembree. They’ll advise on the safest ways to feed your child.

Alcohol consumption: There are no known interactions between Myfembree and alcohol. However, drinking alcohol during treatment with Myfembree could increase the risk of certain side effects, such as liver problems. Talk with your doctor about whether it is safe for you to drink alcohol while taking Myfembree.

As with most medications, Myfembree can cause side effects. Most are mild and usually go away on their own after a few days to weeks. However, Myfembree can also cause serious side effects. Talk with your doctor if you experience any persistent, bothersome, or serious side effects.

If you’d like to learn more about Myfembree, talk with your doctor or pharmacist. They can help answer any questions you have about side effects from taking the drug.

Besides talking with your doctor, you can do some research on your own. These articles might help:

  • More information about Myfembree: For details about other aspects of Myfembree, refer to this article.
  • A look at your condition: For details about heavy menstruation and endometriosis, see our women’s health hub.

Disclaimer: Medical News Today has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.