An abrupt onset of fever, chills, headache, abdominal pain, nausea, and vomiting developed in a previously healthy 16-year-old girl. Viral gastroenteritis was diagnosed, and fluids and hydroxyzine were prescribed. Her symptoms persisted, and she developed painful, and swollen right axillary and cervical lymph nodes. She returned to her physician 3 days after onset of symptoms, and examination revealed a temperature of 37.6°C and lymphadenitis. Infectious mononucleosis was the clinical diagnosis, and propoxyphene-acetaminophen and ice packs were prescribed for the painful adenopathy. She returned the next day with continued painful lymph nodes, increasing weakness, numbness, and tingling sensation of both arms, and blurred vision.