Abstract: A method for achieving long term relief from the symptoms of atopic allergy, comprising parenteral administration of Vitamin B.sub.12 to selected patients, is produced. Vitamin B.sub.12 acts to reduce the levels of reaginic antibody (immunoglobulin) in these patients, and this effect persists beyond the period of treatment. The regimen may include oral administration of Vitamin B.sub.12 as well as other vitamins.