Used as a rescue agent after high-dose methotrexate therapy to reduce toxicity while preserving anticancer effects. Enhances the therapeutic index of 5-fluorouracil in colorectal cancer by stabilizing the binding of fluorouracil’s active metabolite to thymidylate synthase. Employed in the treatment of megaloblastic anemia when oral vitamin B12 or folic acid is ineffective. Investigated in neurological disorders such as autism and cerebral folate deficiency due to its ability to cross the blood-brain barrier and support folate-dependent metabolic processes in the central nervous system. Also used in combination therapies for certain types of drug-resistant malaria and in supportive care during bone marrow suppression.