Final answer:
In patients with infectious mononucleosis due to Epstein-Barr virus, a common reaction to antibiotics like amoxicillin is a maculopapular rash. This rash is related to the presence of heterophile antibodies and is not an allergic reaction to the antibiotic itself. The use of antibiotics is generally not recommended for IM unless a secondary bacterial infection is present.
Step-by-step explanation:
A common reaction in patients with infectious mononucleosis (IM) due to Epstein-Barr virus (EBV) who are treated with amoxicillin or other antibiotics is the development of a rash. This rash is usually maculopapular in nature. It is important to note that this reaction is not an allergic reaction to the antibiotic itself, but rather a result of the underlying infection with EBV. Due to the presence of heterophile antibodies associated with EBV infection there is an increased likelihood of a rash developing when treated with these medications.
In general patients with infectious mononucleosis are advised against taking antibiotics like amoxicillin unless a secondary bacterial infection is suspected. This is because IM is a viral infection and antibiotics are ineffective against viruses. Additionally the use of antibiotics in these cases can lead to unnecessary side effects such as the rash in question.