Dexamethasone is the generic form of the brand-name drug Decadron, which works on the immune system to help reduce itching, swelling, and inflammation.examethasone is a corticosteroid, a class of steroid hormone. The Food and Drug Administration (FDA) approved Decadron in 1958. At that time, Merck & Company made the drug. Now, several manufacturers offer dexamethasone under various brand names and formulations, including Decadron, Ozurdex, Maxidex, and Baycadron.