AbstractFolic acid is a proposed adjunct to alcohol dehydrogenase inhibitors and hemodialysis (HD) in the treatment of methanol toxicity. Although animal models have shown increased formate clearance, human data regarding its efficacy are lacking. We performed a 7-year retrospective chart review of patients with methanol concentrations >10 mg/dL. We compared patients receiving scheduled dosing of 50 mg of folic acid (folate group) to those receiving no folic/folinic acid or <50 mg folic or folinic acid (low/no folate). We excluded patients who did not require hospitalization, those with alternative causes of acidosis, and those who died prior to therapy. The primary outcome measures were worsening metabolic acidosis, length of stay (LOS), and half-life of methanol. Of 27 patient visits with methanol concentration >10 mg/dL, 14 visits (11 patients) met inclusion criteria. Initial pH and methanol concentrations were similar between the two groups. There was no difference in LOS. No patients had worsening metabolic acidosis during therapy. In patients treated with and without HD, median half-lives of methanol were similar in both groups. Folic acid treatment provided no additional benefit to standard therapy for methanol toxicity. We cannot exclude potential benefit of folic acid on formate clearance.