Delayed allergic reactions to beta-lactams. Four cases with intolerance to amoxicillin or ampicillin and good tolerance to penicillin G and V.

Abstract

We present four cases of delayed allergic skin reactions to amoxicillin or ampicillin with good tolerance to benzyl penicillin and phenoxymethyl penicillin. The clinical symptoms reported by the patients, the intradermal skin tests and the controlled challenge results suggested that the mechanism was cellular mediated. In two patients these findings were supported by histopathological studies. Although delayed-type hypersensitivity reactions to beta-lactams with positive skin test seem rare, they can occur to penicillins in allergic patients. The production of these reactions by amoxicillin or ampicillin with good tolerance to benzyl penicillin and phenoxymethyl penicillin emphasizes the role of the side chain in inducing allergic reactions to beta-lactams.