Use of patch testing for identifying allergen causing chronic urticaria.

BACKGROUND AND AIMS The aim of this present study was to evaluate the role of patch testing for the etiological diagnosis of chronic urticaria (CU) by using the Indian standard battery of patch test allergens approved by Contact and Occupational Dermatitis Forum of India (CODFI). METHODS A total of 57 cases with chronic urticaria were tested with the Indian standard battery of allergens. All those cases that showed allergy to patch test allergens were advised to avoid contact with the allergen(s) to whom they had allergy; they were also advised to avoid/restrict allergens in the diet. This avoidance/restriction was advised for a period of six weeks. During this period, clinical improvement of each patient was evaluated and recorded at weekly intervals. RESULTS Out of the 57 cases of CU, 11 patients showed positive reactions to one or more patch test allergens. Nine out of eleven showed complete disappearance of CU by 2-3 weeks on avoidance of the allergen and this improvement continued till the end of six weeks. The remaining two cases showed partial recovery from CU during the same period. CONCLUSION Patch testing is a safe, simple and inexpensive alternative that can be used for the etiological diagnosis of chronic urticaria before undertaking expensive investigations.