Question

A 23 year-old male presents with the rash below. He originally presented to his primary care doctor for a sore throat and was given a prescription for a medication; this rash subsequently broke out. What's the diagnosis and which medication did he receive?

Answer

Rash secondary to Epstein-Barr pharyngitis treated with amoxicillin

• Morbilliform rash occuring in up to 95% of patients given amoxicillin for EBV pharyngitis; the rash typically spreads to the trunk 
• Other types of beta-lactams, cephalosporins, and macrolides may also cause this rash 
• The exact mechanism is unknown but it is non-allergic; researchers have demonstrated that patients may receive amoxicilin after the rash resolves without adverse events.  
• The rash spontaneously resolves in 1-2 weeks

References

Luzuriaga, K., Sullivan, J. Infectious Mononucleosis. N Engl J Med 2010; 362:1993-2000

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