Cefotaxime is a 3rd Generation Cephalosporin and mainly acts by binding to penicillin-binding proteins and inhibits final transpeptidation step of peptidoglycan synthesis, resulting in cell-wall death; resists degradation by beta-lactamase; proper dosing and appropriate route of administration are determined by condition of patient, severity of infection, and susceptibility of microorganism. Indicated in the various conditions like Gonococcal Urethritis/Cervicitis, Gonorrhea, Rectal, Infections Caused by Susceptible Organisms, Prophylaxis of surgical infection. A child of 5 years old of male patient came to pediatrics department with chief complaints of seizures and admitted in pediatrics department-II and his treatment chart was phenytoin 100mg PO BD and valproic acid 200mg – 200 mg – 300 mg Po OD. During his second of treatment child developed fever of 1020F and to reduce the condition physician prescribed cefotaxime 500mg BD IV on 4th day of treatment child developed macular rash all over the body. Better vigilance is necessary for implementation of safe and effective treatment for each individual patient.in order to prevent serious adverse drug reactions of this drug,close monitoring drug treatment course, creating awareness, recognition of the problem and careful management of all the patients who receive medication are essential, because use of cefotaxime causes Colitis, Diarrhea, Elevated blood urea nitrogen (BUN) and creatinine, Elevated hepatic transaminases, Eosinophilia, Fever, Injection site pain, Nausea, Pruritis, Rash, Thrombocytopenia, Transient neutropenia, Vomiting.