Acute generalized exanthematous pustulosis (AGEP) is an uncommon skin disorder most often caused by drugs. Few adverse reactions to sympathomimetic drugs have been reported, despite their extensive use. Although the aetiology of AGEP remains uncertain, recent data have reported involvement of drug-specific T cells and interleukin (IL)-8 production. We characterized an adverse reaction to pseudoephedrine both clinically and immunologically. Histological analysis of skin biopsies confirmed the clinical entity as AGEP, while epicutaneous tests confirmed the specificity of the reaction to the drug. Moreover, immunohistochemical studies showed a mononuclear infiltrate consisting of activated memory T cells in addition to polymorphonuclear cells. Reverse transcription-polymerase chain reaction revealed an increased expression of IL-8 in AGEP-affected skin.