Adrenal insufficiency, a rare disorder which is characterized by the inadequate production or absence of adrenal hormones, may be classified as primary adrenal insufficiency in case of direct affection of the adrenal glands or secondary adrenal insufficiency, which is mostly due to pituitary or hypothalamic disease. Primary adrenal insufficiency affects 11 of 100,000 individuals. Clinical symptoms are mainly nonspecific and include fatigue, weight loss, and hypotension. The diagnostic test of choice is dynamic testing with synthetic ACTH. Patients suffering from chronic adrenal insufficiency require lifelong hormone supplementation. Education in dose adaption during physical and mental stress or emergency situations is essential to prevent life-threatening adrenal crises. Patients with adrenal insufficiency should carry an emergency card and emergency kit with them.