High-dose folic acid for psoriasis - Literature Review & Commentary - Brief Article

Townsend Letter for Doctors and Patients, May, 2003 by Alan R. Gaby

Seven patients with long-standing psoriasis were given 20 mg of folic acid 4 times per day. Marked improvements were noted after 3-6 months of treatment. Three additional patients who had previously received methotrexate treatment for psoriasis were also given folic acid. In one patient, new lesions appeared all over the trunk in places where they had never existed. One patient showed decided worsening and the third patient improved considerably.

Comment: The rationale for using high-dose folic acid is based on the fact that allopurinol, a xanthine oxidase inhibitor, is effective against psoriasis. The author of the present study has found that folio acid fortified with specific amounts of ascorbic acid (to keep it in the reduced state as tetrahydrofolate) is also an effective xanthine oxidase inhibitor. Although no controlled trials have been done with folic acid, other clinicians have observed the same beneficial effect against psoriasis that Oster reported more than a quarter-century ago. Methotrexate interferes with folic acid metabolism and, for reasons that are not clear, appears to cause an adverse reaction to high-dose folic acid in some cases. However, for patients who have not previously been treated with methotrexate, folic acid appears to be a safe and promising therapy for chronic psoriasis. Of course, when using high-dose folic acid, it is important to remember that it can mask the laboratory diagnosis of pernicious anemia.

Oster KA. A cardiologist considers psoriasis. Cutis 1977;20:39-41.