Deflazacort is a synthetic corticosteroid and is used to decrease inflammation. Deflazacort works by acting within cells to prevent the release of certain chemicals that are important in the immune system. These chemicals are normally involved in producing immune and allergic responses, resulting in inflammation. By decreasing the release of these chemicals in a particular area, inflammation is reduced. This can help control a wide number of disease states which are characterised by excessive inflammation. They include severe allergic reactions, inflammation of the lungs in asthma and inflammation of the joints in arthritis.

Deflazacort also decreases the numbers of white blood cells circulating in the blood. This, along with the decrease in inflammatory chemicals, can prevent the rejection of organ transplants, as it prevents the body from attacking foreign tissue. It is also useful for the treatment of certain types of leukaemia, where there is an abnormally large number of certain white blood cells in the tissues or blood. It is also used to treat some diseases which are caused by the immune system attacking itself (autoimmune diseases).

Deflazacort is used in much higher doses than the levels of corticosteroids produced naturally by the body, and as such, the usual actions of corticosteroids become exaggerated and can be observed as side effects of this medicine.