Medical Editor: John P. Cunha, DO, FACOEP Last updated on RxList: 3/28/2022
Korlym Side Effects Center

Medical Editor: John P. Cunha, DO, FACOEP

What Is Korlym?

Korlym (mifepristone) is a cortisol receptor blocker indicated to control high blood sugar levels (hyperglycemia) in adults with endogenous Cushing's syndrome who have type 2 diabetes mellitus or glucose intolerance and have failed surgery or are not candidates for surgery.

What Are Side Effects of Korlym?

Common side effects of Korlym include:

Tell your doctor if you have serious side effects of Korlym including:
  • adrenal insufficiency
  • low potassium levels (confusion, uneven heart rate, extreme thirst, increased urination, leg discomfort, muscle weakness or limp feeling)
  • unusual or irregular vaginal bleeding,
  • a potential for heart conduction abnormalities
  • weakness
  • feeling like you might pass out
  • fever
  • chills
  • cough with yellow or green mucus
  • stabbing chest pain
  • wheezing
  • shortness of breath, or
  • low blood sugar (headache, hunger, weakness, sweating, confusion, irritability, dizziness, fast heart rate, or feeling jittery).

Dosage for Korlym

The recommended starting dose of Korlym is 300 mg once daily. Because of risk of renal impairment, 600 mg once daily should not be exceeded.

What Drugs, Substances, or Supplements Interact with Korlym?

Certain drugs used in combination with Korlym may increase its drug level. Health care professionals must be aware of the potential for drug-drug interactions and adjust dosing or avoid using certain drugs with Korlym.

Korlym During Pregnancy or Breastfeeding

Korlym should never be used by pregnant women. Korlym can cause fetal harm when administered to a pregnant woman because the use of Korlym results in pregnancy loss. If Korlym is used during pregnancy or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential hazard to a fetus. Patients should alert their doctors if they are breastfeeding or plan to breastfeed. Korlym passes into breast milk and may harm unborn babies. Patients should decide with their doctors if it's best to take Korlym or to breastfeed. Women should not do both. Safety and effectiveness in the pediatric population has not been established.

Additional Information

Our Korlym to Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Korlym Consumer Information

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Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Stop using Korlym and call your doctor at once if you have:

  • nausea;
  • unusual weakness or tiredness;
  • a light-headed feeling, like you might pass out;
  • abnormal vaginal bleeding;
  • worsening of any medical problems for which you use steroid medicine;
  • low blood sugar--headache, hunger, weakness, sweating, confusion, irritability, dizziness, fast heart rate, or feeling jittery; or
  • low potassium--leg cramps, irregular heartbeats, fluttering in your chest, muscle weakness or limp feeling.

Common side effects may include:

  • nausea, vomiting, loss of appetite;
  • low potassium;
  • tired feeling;
  • headache, dizziness;
  • pain in your arms and legs;
  • thickened lining of your uterus;
  • swelling in your arms and legs; or
  • high blood pressure.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Read the entire detailed patient monograph for Korlym (Mifepristone)

Korlym Professional Information


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 KORLYM 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.

The most frequently reported adverse reactions (reported in ≥20% of patients, regardless of relationship to KORLYM) were nausea, fatigue, headache, decreased blood potassium, arthralgia, vomiting, peripheral edema, hypertension, dizziness, decreased appetite, and endometrial hypertrophy. Drug-related adverse events resulted in dose interruption or reduction in study drug in 40% of patients.

The adverse reactions that occurred in ≥10% of the Cushing’s syndrome patients receiving KORLYM, regardless of relationship to KORLYM, are shown in Table 1.

Table 1. Treatment Emergent Adverse Events Occurring in ≥10% of Cushing’s Syndrome Patients Receiving KORLYM

Body System/Adverse Reaction Percent (%) of Patients Reporting Event (n = 50)
Gastrointestinal disorders
Nausea 48
Vomiting 26
Dry mouth 18
Diarrhea 12
Constipation 10
General disorders and administration/site conditions
Fatigue 48
Edema peripheral 26
Pain 14
Nervous system disorders
Headache 44
Dizziness 22
Somnolence 10
Musculoskeletal and connective tissue disorders
Arthralgia 30
Back pain 16
Myalgia 14
Pain in extremity 12
Blood potassium decreased 34
Thyroid function test abnormal 18
Infections and infestations
Sinusitis 14
Nasopharyngitis 12
Metabolism and nutrition disorders
Decreased appetite 20
Anorexia 10
Vascular disorders
Hypertension 24
Reproductive system and breast disorders
Endometrial hypertrophy 38*
Respiratory, thoracic, and mediastinal disorders
Dyspnea 16
Psychiatric disorders
Anxiety 10
*The denominator was 26 females who had baseline and end-of-trial transvaginal ultrasound

Laboratory Tests

Reductions in high density lipoprotein-cholesterol (HDL-C) levels have been observed following treatment with KORLYM. In study subjects that experienced declines in HDL-C, levels returned to baseline following discontinuation of drug. The clinical significance of the treatment-related reduction in HDL-C levels in patients with Cushing’s syndrome is not known.

In a study of patients with Cushing’s syndrome, hypokalemia was observed in 44% of subjects during treatment with KORLYM. In these cases, hypokalemia responded to treatment with potassium supplementation and/or mineralocorticoid antagonist therapy (e.g., spironolactone or eplerenone). Hypokalemia should be corrected prior to initiating KORLYM. [See WARNINGS AND PRECAUTIONS]

Elevations of thyroid-stimulating hormone (TSH) were seen in subjects treated with KORLYM. Of the 42 subjects with detectable TSH at baseline, eight (19%) had increases in TSH above the normal range, while remaining asymptomatic. The TSH levels returned to normal in most patients without intervention when KORLYM was discontinued at the end of the study.

Vaginal Bleeding And Endometrial Changes

In Study 400, the thickness of the endometrium increased from a mean of 6.14 mm at baseline (n=23) to 15.7 mm at end-of-trial (n=18) in premenopausal women; in postmenopausal women the increase was from 2.75 mm (n=6) to 7.35 mm (n=8). Endometrial thickness above the upper limit of normal was reported in 10/26 females who had baseline and end-of-trial transvaginal ultrasound (38%). The endometrial thickness returned to the normal range in 3 out of 10 patients 6 weeks after treatment cessation at the end of the study. Vaginal bleeding occurred in 5 out of 35 females (14%). Two of five subjects with vaginal bleeding had normal endometrial thickness. Endometrial biopsies were performed in six patients; five of these patients had endometrial thickening. No endometrial carcinoma was detected in the sampled cases.

Additional Data Fom Clinical Trials

The following are adverse events that were reported in Study 400 at frequencies of ≥ 5% to 10%, and may be related to KORLYM’s mechanism of action:

Gastrointestinal disorders: gastroesophageal reflux, abdominal pain

General disorders and administration site conditions: asthenia, malaise, edema, pitting edema, thirst

Investigations: blood triglycerides increased

Metabolism and nutrition disorders: hypoglycemia

Musculoskeletal and connective tissue disorders: muscular weakness, flank pain, musculoskeletal chest pain

Psychiatric disorders: insomnia

Reproductive system and breast disorders: vaginal hemorrhage, metrorrhagia [See WARNINGS AND PRECAUTIONS]

Adrenal Insufficiency

Adrenal insufficiency was reported in two subjects (4%) in Study 400. The most typical symptoms of adrenal insufficiency were nausea and decreased appetite. No hypotension or hypoglycemia was reported during the events. Adrenal insufficiency resolved in both cases with KORLYM interruption and/or dexamethasone administration.


Generalized, maculo-papular rash was reported in 2 subjects (4%) in Study 400. Two additional subjects developed pruritus (4%). None resulted in discontinuation of KORLYM, and all the events resolved by the end of the study.

Postmarketing Experience

The following adverse reaction has been identified during post approval use of KORLYM. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

- Angioedema

Read the entire FDA prescribing information for Korlym (Mifepristone)

© Korlym Patient Information is supplied by Cerner Multum, Inc. and Korlym Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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