Introduction: Diuretics are a commonly used for the treatment of acute pulmonary edema. However, inappropriate administration of diuretic drugs can result in clinical treatment failure and cause acute pulmonary edema. This is due to rapid decreases in intravascular volume as a result of diuretic treatment. To date, the clinical phenomenon of inappropriate use of diuretics leading to acute pulmonary edema remains unexplored and unrecognized. Here, we report the first case of this problem-pulmonary edema following diuretic therapy. Patient concerns: A 71-year-old male patient who was intubated and transferred to the intensive care unit (ICU) due to respiratory failure was initially diagnosed with pneumonia as a complication of acute respiratory distress syndrome (ARDS). After treatments including antibiotics, lung protective ventilation strategies, and restrictive fluid management, his respiratory symptoms improved. However, the patient's dyspnea became more severe after experimental diuretic therapy. Diagnosis: A point-of-care ultrasound (POCUS) examination showed increased extravascular lung water retention during a hypovolemic state. After full examinations and analysis, the diagnosis of acute pulmonary edema was determined. Interventions: The most likely cause of acute pulmonary edema was left ventricular (LV) hyperdynamic status due to a hypovolemic status caused by excessive diuretic therapy. Consequently, we administrated intravenous fluids and a beta-receptor blocker to the patient. Outcomes: Following these treatment, the patient's respiratory distress improved remarkably. Conclusion: We report the first case of pulmonary edema following diuretic therapy to stress the need of physicians to follow guidelines of clinical practice. Maintaining an appropriate volume status and treatment of beta-receptor blockers is the key to reversing the progress of this adverse effect. In this process, POCUS is a reliable diagnostic tool to identify the cause of acute pulmonary edema and can increase the accuracy of clinical evaluations. It is likely that a wider use of POCUS will help physicians to obtain a faster, and more accurate, diagnosis of the etiology of acute pulmonary edema, thus allowing a more appropriate therapy.