Flare-up of previously negative patch test and intradermal test with amoxicillin after oral provocation

Flare-up reactivity was first described in 1981 in patients with nickel contact eczema as a reactivation of former contact allergy and/or patch test reaction sites because of systemic metal exposure. This phenomenon has been rarely reported for drugs, either as reactivation of formerly positive intradermal test sites or as activation of formerly negative patch test sites and intradermal test sites. Drug flare-up can follow both a patch test and a provocation test. We report a case of flare-up of initially negative patch test and intradermal test sites after oral provocation testing with amoxicillin.