Clinical and laboratory profile of serum sickness-like reaction in children

Classic serum sickness was initially reported after antitoxin therapy for diseases such as diphtheria and tetanus. The illness was shown to be due to an adverse reaction to the antigenic substance of the serum proteins of the animal in which the antitoxin was prepared. Today, it is usually encountered as an adverse effect to certain medications, especially penicillin group of antibiotics. In these cases it is called a serum sickness-like reaction. The aim of this study was to determine the aetiological factors of serum sickness-like reaction, influence of age and sex and clinical manifestations of this disease in Iranian children. The study included all children under 16-year-old who were diagnosed as serum sicknesslike reaction and were admitted in the department of Paediatric Rheumatology in Mofid Children's Hospital between April 2009 and September 2010. Diagnosis was based on history of recent exposure to the antigenic substance that triggered the reaction and the development of signs and symptoms of typical serum sickness. Children with infections that result in a similar clinical picture of fever and rash were excluded from the study. Twenty-eight patients were included in this study. The most common medication causing serum sicknesslike reaction in our study was furazolidone (5 cases, 18%). Cefixime (4 cases, 14%), amoxicillin, co-trimoxazole, cephalexin and co-amoxiclav, (with 2 cases each, 7%) were the other causes of serum sickness-like reaction in this study. The time interval between consumption of antigenic substance in 25 cases (89%) and the appearance of clinical manifestations was 1-3 weeks. Skin rash and angio-oedema was observed in all our patients. Arthralgia was observed in 85%, fever in 75% and arthritis in 36% of patients. As any medication, especially antibiotics may cause serum sickness-like reaction; it is advisable to avoid prescribing unnecessary drugs in children.