ABSTRACT
Influenza B infection, although primarily recognized for respiratory symptoms, can lead to rare but severe cardiac complications such as pericardial effusion and cardiac tamponade. We present a case of a 33-year-old female with morbid obesity who initially exhibited flu-like symptoms, was subsequently diagnosed with influenza B infection, and was discharged with symptomatic treatment. Despite initial discharge, she returned with worsening weakness, gastrointestinal symptoms, and shortness of breath. Imaging studies confirmed pericardial effusion with early signs of tamponade, necessitating an emergent intervention. The patient underwent subxiphoid pericardial window and fluid removal, followed by colchicine treatment to prevent recurrence. Our case highlights the importance of recognizing and promptly managing rare influenza-related complications, particularly in patients without significant comorbidities. It underscores the value of a proactive approach, utilizing point-of-care ultrasound and echocardiography for early diagnosis and intervention to mitigate mortality and morbidity risks associated with pericarditis and cardiac tamponade secondary to influenza B.