Lenalidomide (hemihydrate) is primarily used in the treatment of certain types of cancer and blood disorders. It is commonly prescribed for multiple myeloma, a cancer of plasma cells in the bone marrow, often in combination with other medications like dexamethasone. It is also effective in treating myelodysplastic syndromes (MDS), particularly in patients with a specific chromosomal abnormality known as deletion 5q. Additionally, it is used in the management of mantle cell lymphoma, a rare form of non-Hodgkin lymphoma. The drug works by modulating the immune system, inhibiting the growth of abnormal cells, and promoting their destruction. It is available in oral form, making it convenient for patients to use as part of their treatment regimen. Regular monitoring is required during therapy to manage potential side effects, such as blood clotting risks or lowered blood cell counts.