A 48-year-old male patient developed an acute rash, fever, myalgia, abdominal pain, tachycardia, near syncope, and chest pain after receiving one dose of dupilumab for chronic rhinosinusitis with nasal polyps (CRSwNP). He presented with hypotension, elevated troponin, hypereosinophilia, ST elevation with T wave abnormalities, and a mildly dilated left ventricle with severely reduced systolic function. He was diagnosed with acute myocarditis. He was treated with high-dose steroids, which rapidly alleviated his symptoms and led to a substantial improvement in his heart function.