Fixed drug eruption from amoxycillin.

We present a case of fixed drug eruption on the genital mucosa induced by amoxycillin. Topical provocation was carried out, applying amoxycilin (10% pet) on the glans penis. No reaction was observed. Oral challenge with amoxycillin was followed by pruritic erythema on the glans penis 6 hours after the intake of 125 mg. The study of cross-reactivity to other betalactams showed good tolerance of phenoxymethyl-penicillin, which shares an identical nuclear structure with amoxycillin. The patient also tolerated cephadroxil, a cephalosporin with a side chain identical to that of amoxycillin. On reviewing the literature we have only found three reports of fixed drug eruption fue to amoxycillin.