Mifepristone Side Effects: What to Expect and When to Call Your Doctor

Mifepristone has a well-established safety profile based on more than 25 years of use in the United States and decades of use internationally. Most side effects are predictable and manageable, but there are specific warning signs that require immediate medical attention. This guide covers what to expect when taking mifepristone — both for pregnancy termination (Mifeprex) and for Cushing's syndrome (Korlym), along with a clear guide to when you need to call your doctor.

Side Effects of Mifepristone for Medical Abortion (Mifeprex)

When mifepristone is used in the abortion regimen (200 mg mifepristone on Day 1, followed by misoprostol on Day 2-3), many of the side effects you experience are from the combination — especially misoprostol, which causes uterine contractions. Here's what to expect:

Common Side Effects (Expected and Normal)

• Vaginal bleeding: Heavy bleeding with clots is expected and is the sign the medication is working. Bleeding typically starts within 2-4 hours of taking misoprostol and may be heavier than a normal period. Light spotting can continue for 4-6 weeks. The average duration of bleeding is 9-16 days.
• Abdominal cramping and pain: Strong uterine cramps are common after misoprostol and are typically most intense 2-6 hours after taking the second medication. Ibuprofen (if not contraindicated) can help manage cramping.
• Nausea and vomiting: Nausea is common, especially after misoprostol. Some people vomit. Anti-nausea medications (such as ondansetron) are sometimes prescribed along with the abortion pill regimen.
• Diarrhea: Loose stools or diarrhea typically occur within the first 24 hours after misoprostol and resolve on their own.
• Low-grade fever or chills: A low fever (under 101°F/38.3°C) and chills are common in the first few hours after misoprostol. These typically resolve within 24 hours.
• Headache and dizziness: Common in the first 24-48 hours. Stay well hydrated and rest when needed.

Warning Signs: When to Seek Emergency Care After Mifepristone

The following symptoms require immediate medical attention. Call 911 or go to an emergency room if you experience:

• Soaking more than 2 full-size maxi pads per hour for 2 or more consecutive hours. This level of bleeding may indicate incomplete abortion or hemorrhage requiring medical intervention. About 1% of patients require a surgical procedure to stop heavy bleeding.
• Severe abdominal pain not relieved by ibuprofen. Especially if it persists after 24 hours or worsens. This could indicate an ectopic pregnancy or incomplete abortion.
• Fever over 101°F (38.3°C) persisting for more than 24 hours, or any fever beginning more than 24 hours after misoprostol. This is a warning sign of infection. Serious but rare infections including sepsis (Clostridium sordellii) have been reported. Importantly, sepsis may present WITHOUT fever — watch for general malaise, weakness, rapid heartbeat, and abdominal pain.
• No bleeding within 24 hours of taking misoprostol. This could indicate the medication is not working. Contact your provider.
• Sudden sharp pain in your shoulder. This can be a sign of internal bleeding from a ruptured ectopic pregnancy, which is a medical emergency.

Side Effects of Mifepristone for Cushing's Syndrome (Korlym)

Korlym (mifepristone 300 mg) for Cushing's syndrome is taken daily on an ongoing basis, which means side effect management is different from the short-term abortion regimen. The most common side effects (occurring in 20% or more of patients in clinical trials) include:

• Nausea and vomiting
• Fatigue
• Headache
• Decreased blood potassium (hypokalemia)
• Joint pain (arthralgia)
• Peripheral edema (swelling in hands/feet)
• High blood pressure (hypertension)
• Decreased appetite
• Endometrial hypertrophy (thickening of the uterine lining in women who can become pregnant)

Serious Side Effects of Korlym to Report Immediately

• QT prolongation: Heart rhythm changes. Report chest pounding, chest pain, shortness of breath, or fainting.
• Adrenal insufficiency: Because mifepristone blocks cortisol receptors, the body may produce even more cortisol, but the tissues can't respond. Watch for unusual fatigue, weakness, dizziness, or low blood pressure.
• Severe hypokalemia: Very low potassium can be dangerous. Report irregular heartbeat, muscle weakness, or extreme fatigue.
• Signs of pneumonia: Shortness of breath, cough, fever, or increased mucus production.

Bottom Line on Mifepristone Safety

Mifepristone has been used by millions of people and has a well-established safety record when used as directed. The vast majority of side effects are manageable and expected. Being informed about what is normal and what warrants urgent care is the most important thing you can do. For guidance on drug interactions that may affect side effects, see our mifepristone drug interactions guide. If you're having difficulty accessing mifepristone in the first place, medfinder can call pharmacies near you to find who can fill your prescription.