when in fact they had mononucleosis. An allergic reaction may cause an amoxicillin rash. According to the Centers for Disease ...

“Many people have the Epstein-Barr virus (EBV)—the main viral cause of mononucleosis ... a rash after taking an antibiotic ...

Amoxicillin 600mg ... Monitor closely if skin rash develops; discontinue if lesions progress. Evaluate if diarrhea occurs. Avoid in those with mononucleosis. Hepatic impairment: monitor.