Glutathione and Side Effects: What You Need to Know for Better Health Performance Lab Leucovorin (also called folinic acid) is a folate analog and chemoprotective agent. It's used to rescue healthy cells from the toxic effects of high dose methotrexate, to enhance the effectiveness of fluorouracil (5 FU) ACG Glutathione Extra Strength FDA highlights concerns with using dietary ingredient glutathione to compound sterile injectables FDA Ask the Doctors What do glutathione supplements do? UCLA Health