A – Evidence from a randomized, double-blind trial shows that stopping folic acid in rheumatoid arthritis patients on methotrexate led to higher dropout rates, more gastrointestinal side-effects and episodes of neutropenia, whereas continuing 5 mg daily folic acid prevented these toxicities with no meaningful loss of methotrexate efficacy [Griffith et al., 2000, PMID 11035130]. Subsequent reviews likewise recommend routine, long-term folic acid co-prescription while methotrexate is used [Whittle & Hughes, 2004, PMID 14963199].