Leucovorin is a medication that helps protect healthy cells from the harmful effects of certain chemotherapy drugs, particularly methotrexate. It is a form of folic acid that can enhance the effectiveness of cancer treatments while reducing side effects. In addition to its use in cancer therapy, leucovorin is also used to treat folate deficiency and to counteract the effects of trimethoprim-sulfamethoxazole, an antibiotic. By providing essential nutrients, it supports the body's ability to recover and maintain healthy cell function.