Azacitidine is a medication primarily used to treat certain types of blood cancers, including myelodysplastic syndromes and acute myeloid leukemia. It works by inhibiting the growth of cancer cells and promoting their differentiation, which helps to restore normal blood cell production. This drug is typically administered through injection, either under the skin or into a vein. Patients receiving azacitidine may experience side effects such as nausea, fatigue, and low blood cell counts, which require monitoring by healthcare professionals to ensure safety and effectiveness during treatment.