Stevens-Johnson syndrome is a severe hypersensitivity reaction that typically involves the skin and the mucus membranes, usually occurs as a reaction to a medication or an infection. Most common cause for SJS are drug such as allopurinol, carbamazepine, phenytoin, phenobarbital and cotrimoxazole. 39 year old lady presented with intense erythematous lesions all over the body for past 5 days. The reaction was probably evoked by allopurinol. She was treated with corticosteroids, antimicrobial drugs and oral topical anaesthetics.