Filgrastim, a colony-stimulating factor drug, increases white blood cell production in the bone marrow, particularly neutrophils. Neutrophils, which are essential for fighting infections, can decrease during chemotherapy, resulting in neutropenia. Filgrastim is critical in lowering infection risks in these patients by increasing neutrophil counts. It has applications in a variety of settings, including bone marrow transplants, some malignancies, and myelodysplastic syndrome, where neutropenia is a concern.