Most cases of Addison's disease are caused by the gradual destruction of the adrenal cortex, the outer layer of the adrenal glands, by the body's own immune system. Adrenal insufficiency was first identified by Dr. Thomas Addison in 1849. The symptoms of adrenal insufficiency usually begin gradually. Chronic, worsening fatigue and muscle weakness, loss of appetite, and weight loss are characteristic of the disease. Nausea, vomiting and diarrhea occur in about 50 percent of cases.
Blood pressure is low and falls further when standing, causing dizziness or fainting.
Skin changes also are common in Addison's disease, with areas of hyperpigmentation, or dark tanning, covering exposed and nonexposed parts of the body. Addison's disease can cause irritability and depression. Because of salt loss, craving of salty foods also is common. Hypoglycemia, or low blood sugar, is more severe in children than in adults. In women, menstrual periods may become irregular or stop.