Cortisol, or Hydrocortisone, a topical corticosteroid (1), more specifically a glucocorticoid, produced by the zona fasciculata of the adrenal gland (2). Cortisol is released in response to stress and a low level of blood glucocorticoids. Its primary functions are to increase blood sugar through gluconeogenesis (3); suppress the immune system; and aid in fat, protein and carbohydrate metabolism.