Hydroxyurea is a cytoreductive antineoplastic agent primarily used in the treatment of myeloproliferative disorders, including chronic myeloid leukemia (CML), polycythemia vera, and essential thrombocythemia, where it inhibits DNA synthesis to reduce abnormal blood cell production and lower the risk of thrombotic complications. It is also employed in sickle cell disease and beta-thalassemia to increase fetal hemoglobin levels, thereby reducing the frequency of vaso-occlusive crises, acute chest syndrome, and the need for blood transfusions. Additionally, hydroxyurea is used as an adjunct in certain solid tumors, such as head and neck cancers, often in combination with radiation therapy, and has been investigated in HIV management to potentiate antiretroviral effects by depleting intracellular deoxynucleotides. The drug is administered orally and requires regular hematological monitoring due to risks of myelosuppression and other side effects.