Amoxicillin-Clavulanic Acid-Induced Rash in Epstein-Barr Virus Infection: A Case Report of a Diagnostic Pitfall in a 24-Year-Old Male.

Infectious mononucleosis (IM), caused by the Epstein-Barr virus (EBV), is primarily a self-limiting illness. However, it often mimics bacterial infections, such as bacterial tonsillitis, which can represent a diagnostic pitfall and, consequently, increase the risk of developing complications. The aim of this case report is to highlight the complications resulting from the incorrect differential diagnosis of EBV-induced IM and its clinical significance. We present the case of a 24-year-old male who was initially misdiagnosed with bacterial tonsillitis. Amoxicillin-clavulanic acid was initiated for treatment, after which he developed a widespread maculopapular rash. Acute EBV infection was diagnosed via serological tests. His condition improved following the discontinuation of antibiotic therapy and the administration of supportive symptomatic treatment. This case underscores the critical need for careful differential diagnosis between viral and bacterial tonsillitis. It demonstrates that an amoxicillin-clavulanic acid-induced rash can serve as an important clue for underlying EBV infection, thereby preventing unnecessary antibiotic use and enabling the correct direction of investigation and management.