A 45-year-old woman underwent primary systemic therapy for left breast cancer(cT1N1M0, cStage ⅡA, Luminal B [HER2-positive]). She received EC therapy(epirubicin 90mg/m2, and cyclophosphamide 900mg/m2). On the 4th and 5th day of the third EC cycle, she developed sore throat and a fever of over 38℃, and was not able to consume anything orally. She visited our hospital and underwent a laryngeal endoscopy on the 8th day of the third EC cycle, which revealed severe inflammation of her pharynx and larynx. Viral pharyngolaryngitis was suspected and hence, she was admitted to our hospital. She developed laryngeal edema after hospitalization, for which hydrocortisone was administered. She was discharged from the hospital when her symptoms improved.