An unusual case of infectious mononucleosis complicated by both peritonsillar abscess and postural orthostatic tachycardia syndrome is reported. The patient was diagnosed with Epstein-Barr virus infection early in the disease course by her primary care doctor. She subsequently developed a peritonsillar abscess requiring hospitalisation. Recovery was complicated by the development of postural orthostatic tachycardia syndrome. However, resolution was achieved over the course of approximately 1 year, via conservative measures including graded exercise therapy, without resorting to pharmacotherapy.