Background:Urticaria is a vascular reaction characterized by appearance of wheal which is immunological or non-immunological.Urticaria is one of the most distressing, frustrating and challenging dermatologicalconditions for both patients and doctors.Although usually not life threatening, it often impairs quality of life to a degree comparable with triple coronary heart disease.Only curative treatment is to find out cause and eliminate. Aims: To study the various aetiology of urticaria and to perform Autologous Serum Skin Test (ASST) as a screening test in chronic spontaneous urticaria (CSU).Materials and Methods:A prospective study of aetiology of urticaria in 312 patients was carried out over a period of 3 years in skin outpatient department at tertiary care hospital.The diagnosis was based on history and confirmed by elimination and rechallenge in less severe cases of food and drug.CSUwas diagnosed after excluding other aetiology and ASST was performed in all cases of urticaria labelled as CSU. Specific investigations like TSH were done as and when necessary.Statistical analysis: mean, standard deviation, chi square test, z test. Results:Most common type wasCSU(28.21%) followed by food (25.64%), drugs(21.47%) and physical urticarial (10.89%).Urticaria associated with infection in 4.8%, multiple causes(2.88%) and by aerosol (dust/mite/pollen in 2.24%). Atopy in 1.28%, mosquito bite, associated with thyroid disease, contrast induced,premenstrual precipitation etc. were found in <1%. Among CSU 19.31%were ASST positive.Conclusion: Most common type of urticaria was CSU followed by food and drugs. Among food most common cause was citrous food. Most common drug causing urticaria were NSAIDS followed by Sulphonamides and cephalosporin.  

Keywords: Urticaria; Angioedema; Aetiology; CSU; ASST.