This is a case report of immediate acute pulmonary edema following the intravenous administration of Stronger Neo-Minophagen C (glycyrrhizin) and Chlor-Trimeton (chlorpheniramine maleate). The patient was a 15-year-old Japanese boy who had a previous history of surgery for right testicular tumor and adverse reactions to contrast media. The patient complained of severe headache, nausea, and vomiting just before the end of intravenous administration of these drugs, which were being given to prevent an adverse reaction to contrast enhanced CT. The symptoms disappeared within a few minutes, but chest CT examination performed immediately after the onset of the adverse reaction showed ill-defined consolidations with air bronchogram, especially in the anterior portion of both lungs. One day later, the abnormalities coalesced and poorly marginated patchy opacities developed. A week later, the abnormal densities disappeared. CT findings suggested acute pulmonary edema, especially in the anterior portion of both lungs. Thus CT examination was useful to detect focal pulmonary edema even in a patient with no particular respiratory symptom.