Understanding Estradiol/Norethindrone/Relugolix Side Effects

When your doctor prescribes Myfembree — the brand name for Estradiol/Norethindrone/Relugolix — one of the first things you'll want to know is: what will this medication actually feel like? What side effects should you expect, and which ones mean you need to call your doctor right away?

This guide breaks down the side effects based on FDA labeling and clinical trial data so you know exactly what to watch for.

What Is Estradiol/Norethindrone/Relugolix?

Estradiol/Norethindrone/Relugolix (Myfembree) is a once-daily combination tablet used to manage heavy menstrual bleeding from uterine fibroids and moderate to severe endometriosis pain in premenopausal women. It works by suppressing estrogen production through a GnRH receptor antagonist (Relugolix) while adding back low doses of Estradiol and Norethindrone Acetate to protect your bones and reduce the intensity of menopause-like symptoms. For more details, see our complete guide on what Estradiol/Norethindrone/Relugolix is and how it's used.

Common Side Effects

These side effects were reported frequently in clinical trials. Most are mild to moderate and often improve as your body adjusts to the medication over the first few weeks to months:

• Hot flashes and vasomotor symptoms — The most commonly reported side effect. Even with the add-back hormones, some hot flashes may occur, especially in the first few months.
• Night sweats — Related to hot flashes, these can disrupt sleep. Keeping your bedroom cool and using moisture-wicking bedding may help.
• Headache — A common side effect that usually responds to over-the-counter pain relievers.
• Menstrual period changes — You may experience irregular bleeding, spotting, or your periods may stop entirely. This is expected and usually a sign the medication is working.
• Hair loss (alopecia) — Some women notice increased hair shedding. This is typically temporary.
• Decreased libido — A reduction in sex drive can occur due to the hormonal changes caused by the medication.
• Mood changes — Irritability, mood swings, and emotional sensitivity have been reported.
• Nausea — Usually mild and may improve if you take the medication with food.
• Muscle or joint pain — Some women experience body aches, particularly in the first few weeks.
• Fatigue — Feeling more tired than usual is common, especially early in treatment.
• Dizziness — Typically mild and short-lived.

Serious Side Effects

These side effects are less common but require immediate medical attention. Myfembree carries a boxed warning — the FDA's most serious safety warning — about certain cardiovascular risks.

Blood Clots and Cardiovascular Events (Boxed Warning)

The estrogen and progestin components of Estradiol/Norethindrone/Relugolix increase the risk of:

• Deep vein thrombosis (DVT) — Blood clots in the legs. Symptoms include leg swelling, pain, warmth, or redness in one leg.
• Pulmonary embolism (PE) — Blood clots that travel to the lungs. Symptoms include sudden shortness of breath, chest pain (especially when breathing deeply), rapid heartbeat, or coughing up blood.
• Stroke — Sudden numbness or weakness (especially on one side), confusion, trouble speaking, vision changes, severe headache, or loss of balance.
• Heart attack (myocardial infarction) — Chest pain or pressure, pain spreading to the arm, jaw, or back, shortness of breath, cold sweats, or nausea.

Call 911 immediately if you experience any of these symptoms.

The risk is higher in women over 35 who smoke, and in women with uncontrolled high blood pressure, high cholesterol, vascular disease, or obesity.

Other Serious Side Effects

• Bone mineral density loss — Estradiol/Norethindrone/Relugolix can cause bone thinning that may not be fully reversible. Your doctor should monitor your bone density with DXA scans during treatment. Treatment is limited to 24 months partly because of this risk.
• Suicidal ideation and mood disorders — Depression and suicidal thoughts have been reported. Contact your doctor immediately if you experience worsening depression, feelings of hopelessness, or thoughts of self-harm.
• Liver injury — Elevated liver enzymes (transaminases) have been reported. Symptoms of liver problems include yellowing of the skin or eyes (jaundice), dark urine, persistent nausea, or upper right abdominal pain.
• Gallbladder disease — Estrogen-containing medications can increase the risk of gallstones. Watch for sudden severe abdominal pain, especially after eating fatty foods.
• Elevated blood pressure — Your doctor should monitor your blood pressure during treatment.
• Allergic reactions — Rare but serious. Symptoms include hives, facial or throat swelling (angioedema), difficulty breathing, or anaphylaxis. Seek emergency care immediately.

Specific Populations

• Pregnancy — Estradiol/Norethindrone/Relugolix is contraindicated in pregnancy. A pregnancy test is required before starting treatment, and you must use non-hormonal contraception while taking it.
• Breastfeeding — Not recommended during breastfeeding.
• Women over 35 who smoke — At significantly higher risk for blood clots and cardiovascular events. Many doctors will not prescribe Myfembree to women in this group.
• Women with osteoporosis risk factors — Extra caution and monitoring needed since the medication can accelerate bone loss.
• Liver disease — Myfembree is contraindicated in women with hepatic impairment.

How to Manage Common Side Effects

Many side effects improve on their own within the first 1 to 3 months. Here are practical tips:

• Hot flashes and night sweats: Dress in layers, keep your bedroom cool, avoid triggers like caffeine, spicy foods, and alcohol. Some women find deep breathing exercises helpful during a hot flash.
• Headaches: Stay hydrated and get adequate sleep. Acetaminophen or ibuprofen can help, but talk to your doctor if headaches are persistent or severe.
• Nausea: Try taking the medication with a small meal or snack.
• Mood changes: Keep a mood diary to track patterns. Regular exercise and adequate sleep can help. Talk to your doctor if mood changes become severe or persistent.
• Hair loss: This is usually temporary. A gentle hair care routine and biotin supplements may help, though evidence is limited.
• Fatigue: Maintain a regular sleep schedule, stay physically active, and consider whether other factors (like stress or iron deficiency from previous heavy bleeding) may be contributing.

If any side effect becomes severe, persistent, or significantly impacts your quality of life, contact your prescriber. Dose adjustments aren't possible with this fixed-dose combination tablet, but your doctor may recommend supportive treatments or evaluate whether continuing is the right choice.

Final Thoughts

Every medication has trade-offs. For many women with debilitating fibroid bleeding or endometriosis pain, the benefits of Estradiol/Norethindrone/Relugolix outweigh the side effects — especially since the built-in add-back therapy reduces the severity of symptoms compared to older GnRH treatments like Lupron.

The key is knowing what to watch for and staying in close communication with your doctor throughout treatment. Keep all follow-up appointments, report new symptoms promptly, and don't hesitate to call your provider if something doesn't feel right.

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