Lenalidomide 10 mg is a prescription medication used to treat certain types of anemia (low red blood cell count) caused by an abnormality in the bone marrow, known as myelodysplastic syndromes (MDS), and multiple myeloma (a type of cancer of the plasma cells). It is also used in combination with other medications to treat mantle cell lymphoma (MCL, a type of non-Hodgkin's lymphoma). Lenalidomide 10 mg comes in the form of a tablet that is taken by mouth, usually once daily. It is important to take lenalidomide according to your doctor's instructions. Common side effects include diarrhea, nausea, constipation, and fatigue.