Keytruda is a medication used in cancer treatment, specifically designed to help the immune system recognize and attack cancer cells. It is classified as an immune checkpoint inhibitor, which means it blocks a protein called PD-1 that tumors use to evade detection by the immune system. By inhibiting this protein, Keytruda enhances the body's ability to fight certain types of cancer. This drug is commonly prescribed for various cancers, including melanoma, lung cancer, and bladder cancer. It is administered through an intravenous infusion and is often part of a broader treatment plan. Patients receiving Keytruda may experience side effects, which can vary in severity.