Add-on therapy with 4,000 International Units (IUs) of vitamin D3 per day could be considered safe and potentially beneficial in patients with chronic hives, the authors reported online February 7 in Annals of Allergy, Asthma & Immunology.
But principal investigator Dr. Jill A. Poole of the University of Nebraska Medical Center in Omaha cautioned by phone with Reuters Health that "urticaria is usually a tough disease to treat; in our study, vitamin D was an add-on therapy, not a cure."
"We studied doses that are readily available over the counter, 600 IU vs 4,000 IU, which is the National Institute of Medicine's upper safe limit for adults, and patients on 4,000 IU had a 40% reduction in their hives symptoms," she said.
"But vitamin D has a long half-life and needs to be given for up to three months to reach a steady state in the body. We didn't see effects until the end of the study at three months," she added.