This has been confirmed by other laboratories. A virus, dru g , or other putative target antigen may be responsible for incit-ing this autoimmune process. In the evaluation of urticaria, taking a careful history, is the most important aspect. It is important to remember to search for allergens such as foods and drugs, and to inquire about infections and physical stimuli as being pre-cipitating causes. The physical examination will provide clues for further investigations.
Physical challenges are useful to identify patients with associated physical urticaria.
Skin testing should only be used to confirm the history. Skin biopsy is reserved for patients with atypical urticarial lesions to rule out a necro-tizing vasculitis. In the treatment of urticaria, all patients should be coun-seled to avoid specific aggravating factors, be it foods or d rugs. A strict elimina-tion diet may be tried but generally this is not useful. If it is used it should be done so for only short periods of time.