Recurrent pulmonary embolism and azygos vein thrombosis during varenicline therapy for smoking cessation

Venous thromboembolism (VTE) associated with varenicline is extremely rare. We present the case of a young woman who experienced two distinct episodes of pulmonary embolism (PE) while taking varenicline. The patient developed her first episode of PE two months after varenicline use. Four years later, she experienced a second episode of PE and azygos vein thrombosis three weeks after restarting varenicline. Both episodes occurred in the absence of any identifiable provoking factors. Her family history of VTE was negative, and an evaluation of hypercoagulability revealed no abnormalities. We report the first documented case of recurrent PE and the first case of azygos vein thrombosis associated with varenicline use. This case may suggest a potential association between varenicline use and VTE. Clinicians should assess the VTE risk and closely monitor patients taking varenicline.