Chemotherapy drug. Vial of the injectable drug decadron, used for chemotherapy to treat patients with cancer. Other vials are in the background. Decadron is a steroid, and it can be injected intravenously (into the bloodstream) for immediate effect. Tablets are then taken to maintain the effect. Decadron is commonly used to treat brain cancers, Hodgkin's Disease and Multiple Myeloma. Decadron is injected in a phosphate form called dexamethasone phosphate. Dosages range from 1 to 5 millilitres, with a usual dose being 1 millilitre. Decadron is also used to treat other diseases, such as tuberculosis or eye allergies.