Hydrocortisone is used alone or with other medications to treat the symptoms of low corticosteroid levels (lack of certain substances that are usually produced by the body and are needed for normal body functioning). Hydrocortisone is also used to treat other conditions in patients with normal corticosteroid levels. These conditions include certain types of arthritis; severe allergic reactions; lupus (a disease in which the body attacks many of its own organs); and certain conditions that affect the lungs, skin, eyes, kidneys, blood, thyroid, stomach, and intestines. It is also sometimes used to treat the symptoms of certain types of cancer. Hydrocortisone is in a class of medications called corticosteroids. It works to treat patients with low levels of corticosteroids by replacing steroids that are normally produced naturally by the body. It works to treat other conditions by reducing swelling and redness and by changing the way the immune system works.