What the label lists and what reports show
Mifepristone side effects
Mifepristone's FDA label: “Most common adverse reactions in Cushing's syndrome (≥ 20%): nausea, fatigue, headache, decreased blood potassium, arthralgia, vomiting, peripheral edema, hypertension, dizziness, decreased appetite, endometrial hypertrophy ( 6 ).” FAERS holds 4,696 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is nausea (794 reports).
- Generic listed
- Boxed warning
Check it at the source: the mifepristone FDA label on DailyMed (effective September 25, 2025, Corcept Therapeutics Incorporated); the FDA FAERS public dashboard.
What does the patient leaflet say about side effects?
From the patient leaflet: What are the possible side effects of mifepristone?Mifepristone can cause serious side effects including: See “What is the most important information I should know about mifepristone?” loss of pregnancy reduced effects of adrenal hormones (adrenal insufficiency). Mifepristone stops an adrenal hormone in your body called cortisol from working. Tell your doctor right away if you have any symptoms of adrenal insufficiency. Symptoms may include: unusual tiredness or weakness nausea fatigue low blood pressure (hypotension) low blood sugar (hypoglycemia) low blood potassium (hypokalemia). Your doctor should check the level of potassium in your blood before you start taking mifepristone and while you take it. Tell your doctor if you have any signs of low potassium. Signs may include: muscle weakness, aches, or cramps abnormal or irregular heartbeats (palpitations) bleeding from the vagina. […]
Source: FDA drug label, Corcept Therapeutics Incorporated, effective September 25, 2025 (SPL set 63c068cd-9370-460f-829b-70e8c7ebe91e), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsMost common adverse reactions in Cushing's syndrome (≥ 20%): nausea, fatigue, headache, decreased blood potassium, arthralgia, vomiting, peripheral edema, hypertension, dizziness, decreased appetite, endometrial hypertrophy ( 6 ).
Table 2. Treatment Emergent Adverse Events Occurring in ≥10% of Cushing's Syndrome Patients Receiving mifepristone
| Body System/Adverse Reaction | Percent (%) of Patients Reporting Event (n = 50) *The denominator was 26 females who had baseline and end-of-trial transvaginal ultrasound Gastrointestinal disorders |
|---|---|
| Nausea | 48 |
| Vomiting | 26 |
| Dry mouth | 18 |
| Diarrhea | 12 |
| Constipation | 10 |
| Fatigue | 48 |
| Edema peripheral | 26 |
| Pain | 14 |
| Headache | 44 |
| Dizziness | 22 |
| Somnolence | 10 |
| Arthralgia | 30 |
| Back pain | 16 |
| Myalgia | 14 |
| Pain in extremity | 12 |
| Blood potassium decreased | 34 |
| Thyroid function test abnormal | 18 |
| Sinusitis | 14 |
| Nasopharyngitis | 12 |
| Decreased appetite | 20 |
| Anorexia | 10 |
| Hypertension | 24 |
| Dyspnea | 16 |
| Anxiety | 10 |
Rows and numbers as the label prints them, under its own column headings (the first rows of a longer table where it runs on). A reaction in a trial table is not necessarily caused by the medicine, and trials differ from everyday use.
From the label: adverse reactions, continuedMost common adverse reactions in Cushing's syndrome (≥ 20%): nausea, fatigue, headache, decreased blood potassium, arthralgia, vomiting, peripheral edema, hypertension, dizziness, decreased appetite, endometrial hypertrophy ( 6 ). To report suspected adverse reactions, contact Corcept Therapeutics at 1-855-844-3270 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, the adverse reaction rates observed cannot be directly compared to rates in other clinical trials and may not reflect the rates observed in clinical practice. Safety data on the use of mifepristone are available from 50 patients with Cushing's syndrome enrolled in an uncontrolled, open-label, multi-center trial (Study 400). Forty-three patients had Cushing's disease and all except one had previously undergone pituitary surgery. Four patients had ectopic ACTH secretion, and three had adrenal carcinoma. Patients were treated for up to 24 weeks. A dose of 300 mg per day was administered for the initial 14 days; thereafter, the dose could be escalated in increments of 300 mg per day based on assessments of tolerability and clinical response. Doses were escalated up to 900 mg per day for patients <60 kg, or 1200 mg per day for patients >60 kg.
Source: FDA drug label, Corcept Therapeutics Incorporated, effective September 25, 2025 (SPL set 63c068cd-9370-460f-829b-70e8c7ebe91e), via openFDA; the full label on DailyMed
What do FAERS reports show?
4,696 reports list mifepristone among the medicines taken, each a report of something that happened, not proof the medicine caused it; 346 are coded as a death and 1,387 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 24 reactions below, 15 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
Reports received each year
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Mifepristone: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions