Fluorouracil is a medication primarily used in the treatment of certain types of cancer, including breast cancer, colon cancer, and skin cancer. It works by interfering with the growth of cancer cells, ultimately slowing their proliferation. Fluorouracil is often administered through injection or topical application, depending on the specific condition being treated. In addition to its use in cancer therapy, Fluorouracil can also be applied to treat actinic keratosis, a skin condition caused by sun damage. While effective, it may cause side effects such as nausea, mouth sores, and skin irritation. Regular monitoring by healthcare professionals is essential during treatment.