A 93-year-old woman was admitted to our hospital with wheezing and oxygen desaturation after a meal. Unenhanced chest computed tomography (CT) showed a bulky mediastinal tumor surrounding the trachea and an esophageal foreign body, with compression of the tracheal bifurcation resulting in a severe tracheal stenosis. The foreign body was removed with an upper gastrointestinal endoscope, reversing the hypercapnic respiratory failure. We identified the foreign body as a polycarbophil calcium (PC) tablet. This drug exerts its medical effects in a gelatinous form; however, by using porcine esophagus, we confirmed that PC tablets may swell while maintaining their shape and subsequently adhere to the esophageal mucosa. This seemed to have contributed to further obstruction of the trachea in our patient. This is the first case report of tracheal stenosis with a PC tablet lodged in the esophagus. Thus, we recommend that care be taken when this drug is prescribed and administered.