Infectious mononucleosis (IM) is caused by Epstein-Barr virus (EBV), and the condition is characterized by sore throat, fever, lymphadenopathy, and atypical lymphocytosis. These infections are common in early childhood, with a second peak occurring in late adolescence. EBV is spread by contact with oral secretions. Most cases of IM are self-limited. However, there are associated complications, some of which can be serious and fatal. We report the case of a 20-year-old man with splenic infarction and exuberant peritonsillar abscess secondary to an EBV infection. This case highlights the importance of accurate diagnoses and frequent monitoring in IM patients, given the risk of airway obstruction.