Vincristine is a chemotherapy medication used primarily to treat various types of cancer, including leukemia and lymphoma. It works by inhibiting the ability of cancer cells to divide and grow, which helps to slow down or stop the progression of the disease. This drug is usually administered through an injection into a vein and is often part of a combination therapy with other cancer treatments. Common side effects may include nausea, hair loss, and constipation, but it is generally well-tolerated when monitored by healthcare professionals.