Hydrocortisone injection is used to treat symptoms of low corticosteroid levels (lack of certain substances that are usually produced by the body and are needed for normal body functioning). It is also used to treat severe allergic reactions. Hydrocortisone injection is used in the management of multiple sclerosis (a disease in which the nerves do not function properly), lupus (a disease in which the body attacks many of its own organs), gastrointestinal disease, and certain types of arthritis. Hydrocortisone injection is also used to treat certain conditions that affect the blood, skin, eyes, nervous system, thyroid, kidneys, and lungs. Hydrocortisone injection is in a class of medications called corticosteroids. It works to treat people with low levels of corticosteroids by replacing steroids that are normally produced naturally by the body. It also works to treat other conditions by reducing swelling and redness and by changing the way the immune system works.