Dexamethasone is a synthetic corticosteroid and is used to control symptoms caused by low levels of corticosteroids in the body. This can be due to many reasons, including Addison's disease or surgical removal of the adrenal gland(s). Low blood levels of corticosteroids must be treated with replacement therapy to allow the body to function normally. Corticosteroids affect the strength of heart muscle and its response to natural chemicals affecting heart rate. They affect the water and salt balance in the body and ... enable the body to cope with stress. Stress includes changes in temperature, pain, fear, anxiety and illness and can be hazardous if the body is not equiped to cope, due to low levels of corticosteroids.