Folinic acid is widely used in medical treatments, particularly as an antidote to counteract the toxic effects of methotrexate, a chemotherapy drug. It helps protect healthy cells while allowing methotrexate to target cancer cells effectively. Additionally, it is used in the treatment of folate deficiency, which can lead to anemia and other health issues. In combination with fluorouracil (5-FU), it enhances the efficacy of chemotherapy for colorectal cancer. Folinic acid is also employed in reducing the side effects of certain medications that interfere with folate metabolism. Beyond oncology, it plays a role in supporting neurological health and is sometimes used in treating conditions like cerebral folate deficiency. Its ability to act as a folate source makes it valuable in various therapeutic and supportive care applications.