Cardiogenic pulmonary edema usually presents with characteristic clinical features and bilateral infiltrates on the chest radiograph. Rarely, pulmonary edema may manifest unilaterally, leading to a mistaken diagnosis of a primary lung pathology. We present a 30-year-old man who developed acute coronary syndrome following an overdose of alprazolam. He developed breathlessness with unilateral infiltrates on the chest radiograph. Echocardiography revealed regional wall motion abnormalities related to underlying ischemia and acute mitral regurgitation with an eccentric jet. Besides, he had significant impairment of left ventricular systolic function. His coronary angiogram revealed a slow-flow phenomenon in the right coronary and left anterior descending artery territories. Ischemia-related dysfunction of the posterolateral papillary muscle probably led to a floppy posterior mitral leaflet and an eccentrically directed regurgitant jet, leading to unilateral pulmonary edema. He was commenced on dual antiplatelet therapy, heparin infusion, atorvastatin, frusemide, and ramipril, following which he showed gradual clinical improvement along with resolution of the radiological infiltrates. His left ventricular function improved, and the mitral valve function normalized on echocardiography within a week.