Medications for neutropenia are used to lower the risk for infection in people with low white blood cell counts from certain cancer treatments, such as chemotherapy or bone marrow transplants. Some of these medications also have other uses, such as treating severe chronic neutropenia. They work by stimulating the bone marrow to make more white blood cells, helping your body fight infections. Common classes include granulocyte colony-stimulating factors (G-CSFs) and granulocyte-macrophage colony-stimulating factors (GM-CSFs). G-CSFs, like Neupogen (filgrastim) and Neulasta (pegfilgrastim), are usually given as injections. GM-CSFs, such as Leukine (sargramostim), are also available in injectable forms. These options provide different ways to help increase your white blood cell count and support your immune system.