What Is Cushing Syndrome?

Cushing syndrome, also known as hypercortisolism, is a condition in which your body overproduces a hormone called cortisol.

Cortisol helps to regulate a variety of processes in the body. These processes include:

  • Controlling blood sugar levels
  • Regulating metabolism
  • Influencing blood pressure
  • Controlling salt and water balance
  • Influencing mood and memory
  • Acting as an anti-inflammatory
  • Helping to regulate immune responses
  • Helping the body respond to stress

The effect of cortisol on the body

Normally, cortisol is produced in varying amounts over the course of the day. Levels are generally high in the morning and low at night. In Cushing syndrome, your body produces too much cortisol and no longer follows this natural rhythm.

What causes Cushing syndrome?

The causes of Cushing syndrome are categorized in 2 ways. Either the cause is something inside the body (known as endogenous—most commonly noncancerous tumors) or something that comes from outside the body (known as exogenous—most commonly certain medications), as shown below:

Causes inside the body (endogenous)

adrenal adenoma tumor

Adrenal tumor
located in the adrenal gland

Leads to overproduction of cortisol by the adrenal glands

pitutary adenoma tumor

Pituitary tumor
located in the pituitary gland

(Cushing Disease)

etopic tumor

Ectopic tumor
located elsewhere in the body or other/unknown causes

Leads to too much of a hormone called adrenocorticotropic hormone (ACTH) being produced, resulting in overproduction of cortisol by the adrenal glands

Causes outside the body (exogenous)

Taking medicines containing steroids, such as prednisone


  1. Nieman LK, Ilias I. Evaluation and treatment of Cushing’s syndrome. Am J Med. 2005;118(12):1340-1346.
  2. Nieman L, Swearingen B. Cushing’s Syndrome and Cushing’s Disease: Your Questions Answered. New York, NY: The Pituitary Society; 2013.
  3. The Society for Endocrinology. You and Your Hormones website. https://www.yourhormones.info/hormones/cortisol. Accessed October 30, 2017.
  4. Sharma ST, Nieman LK, Feelders RA. Cushing’s syndrome: epidemiology and developments in disease management. Clin Epidemiol. 2015;7:281-293.
  5. Guaraldi F, Salvatori R. Cushing syndrome: maybe not so uncommon of an endocrine disease. J Am Board Fam Med. 2012;25(2):199-208.


Most Important Information About Korlym

Korlym should never be taken by women who are pregnant or who might become pregnant. Taking Korlym during pregnancy will result in the loss of a pregnancy. A pregnancy test is required before starting Korlym or if treatment is interrupted for more than 14 days. Talk with your doctor about how to prevent pregnancy.

Tell your doctor and pharmacist about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements. Korlym and certain other medicines, may affect each other or may cause side effects.

Do not take Korlym if:

  • you are taking certain medications for high cholesterol, such as simvastatin (e.g., Zocor®) or lovastatin (e.g., Mevacor®), as Korlym may cause a dangerous increase in the level of these medications in the blood
  • you take corticosteroid medications like prednisone to treat a serious medical condition
  • you have experienced unexplained vaginal bleeding, changes in the cells lining your uterus (endometrial hyperplasia), or cancer of the lining of your uterus (endometrial cancer)

What Are the Possible Side Effects of Korlym?

Patients taking Korlym should be monitored for side effects. Potential serious side effects include signs of adrenal insufficiency, low potassium levels, changes to the lining of the uterus, vaginal bleeding, and problems with the electrical system of the heart.

The most common side effects of Korlym include nausea, fatigue, headache, low potassium in the blood, pain in arms and legs (arthralgia), vomiting, swelling of arms and legs (peripheral edema), high blood pressure, dizziness, decreased appetite, and thickening of the lining of the uterus (endometrial hypertrophy).

Tell your doctor if you have any side effect that bothers you or that does not go away.

These are not all of the possible side effects of Korlym. For more information, ask your doctor or pharmacist. For medical advice about side effects, call your doctor.

Before taking Korlym, talk to your doctor if you are breastfeeding or plan to breastfeed.

Complete warnings and other important safety information are available in the full Prescribing Information and Medication Guide.

What Is Korlym® (mifepristone) 300 mg Tablets?

Korlym is a prescription medicine used to treat high blood sugar (hyperglycemia) caused by high cortisol levels in the blood (hypercortisolism) in adults with endogenous Cushing syndrome who have type 2 diabetes mellitus or glucose intolerance and who cannot have surgery or for whom surgery has failed. Korlym is not for people who have type 2 diabetes mellitus not caused by Cushing syndrome.