Pseudoephedrine hydrochloride (PEH) is a sympathomimetic agent that is widely used in common cold disease in children. Though side effects of PEH are well known, it is preferred by many pediatricians in order to benefit from its symptomatic relief in common cold disease. A case of acute urinary retention due to PEH in a three-year-old boy is reported. The aim of this case report is to emphasize the clinical importance and differential diagnosis of PEH overdose in children and to discuss the appropriate treatment approach to PEH overdose in the emergency department.