Folinic acid calcium salt hydrate is widely used in medical treatments, particularly as an antidote for methotrexate toxicity. It helps rescue healthy cells from the harmful effects of methotrexate, a chemotherapy drug, by providing an alternative pathway for DNA synthesis.

In oncology, it is often combined with fluorouracil (5-FU) to enhance the effectiveness of chemotherapy in treating colorectal cancer. It works by stabilizing the binding of 5-FU to its target enzyme, improving the drug's ability to inhibit cancer cell growth.

This compound is also utilized in the treatment of folate deficiency, where it acts as a biologically active form of folic acid, supporting red blood cell production and preventing anemia. Additionally, it is used in leucovorin rescue therapy to mitigate the side effects of high-dose methotrexate in cancer patients.

In prenatal care, it is sometimes administered to reduce the risk of neural tube defects in developing fetuses, especially in women with a history of such conditions or those on certain medications that interfere with folate metabolism. Its role in supporting cellular repair and growth makes it a valuable component in various therapeutic applications.