Cephalexin rash in infectious mononucleosis.

The ampicillin rash occurring in cases of infectious mononucleosis is well documented. Similar phenomena have also been observed with other antibiotics. The case of a patient with infectious mononucleosis treated with cephalexin who later showed a rash is presented and the previous literature is reviewed. The rash seen in this patient, who was treated with cephalexin, may be similar to the rash seen with ampicillin treatment of patients with infectious mononucleosis. The mechanism by which these eruptions occur is not completely understood, although there are many interesting theories. Perhaps rashes during infectious mononucleosis in association with other antibiotics are actually more common, but just not recognized. A heightened awareness of this possibility may therefore lead to recognition of more cases and further understanding of this entity.