What do systematic reviews say?

Summary of findings: Folic acid vs placebo

Folic acid showed no clear difference in haematological disorders (incidence of neutropenia, etc) compared with placebo (low certainty).

• Folic acid and folinic acid for reducing side effects in patients receiving methotrexate for rheumatoid arthritis 2013 · Cochrane Headline outcomes only
  RR 1.7 [0.42, 6.96]
  2 studies · 443 participants
  Low