OverviewHives (urticaria) are raised, red, itchy welts, seen here on the arm. The majority of urticaria develop as a result of allergic reactions. Occasionally, they may be associated with autoimmune diseases, infections (parasitosis), drugs, malignancy, or other causes.
Update Date 6/17/2012
Updated by: Stuart I. Henochowicz, MD, FACP, Associate Clinical Professor of Medicine, Division of Allergy, Immunology, and Rheumatology, Georgetown University Medical School. David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.