Cushing's syndrome is an uncommon disorder caused by the body being exposed to too much cortisol for a long time. The most frequent cause is long-term use of steroid medication; less often it comes from a tumor of the pituitary or adrenal glands.
Its more specific signs — a rounded "moon" face, weight gain around the middle, purple or pink stretch marks, easy bruising, thinning skin, and muscle weakness — help distinguish it from the vague symptoms people often blame on stress. It is diagnosed by a clinician with blood, urine, or saliva tests, not a home test. See high cortisol symptoms for how this differs from everyday stress.