Cortisol is a corticosteroid hormone produced by the adrenal cortex (in the adrenal gland). It is a vital hormone that is often referred to as the "stress hormone" as it is involved in the response to stress. It increases blood pressure, blood sugar levels and has an immunosuppressive action. In pharmacology, the synthetic form of cortisol is referred to as hydrocortisone, and is used to treat allergies and inflammation as well as cortisol production deficiencies. When first introduced as a treatment for rheumatoid arthritis, it was referred to as Compound E.