A 6-year-old boy was diagnosed with the left lower lobe pneumonia and pleural effusion and was put on parenteral cefotaxime and clindamycin treatment. He then improved clinically and was discharged 7 days later with oral amoxicillin clavulanate treatment. After four days, however, he was readmitted to the hospital with fever and cough. A chest X-ray revealed left lower lobe pneumonia and pleural effusion. As a case of complicated pneumonia was considered, we started parenteral cefotaxime and clindamycin treatment, 10 days after which his clinical and radiological findings were improved. At the 12th of day of hospitalization, however, he developed at 39°C, which we considered as a side effect of antibiotics. Therefore, antibiotic treatment was stopped. At the same day, he also developed a generalized maculopapular erythematous rash, which was considered an allergic reaction secondary to antibiotics (Figure 1).