BACKGROUND: Adverse reactions to alcoholic beverages are common and more frequently mediated by immunological mechanisms than previously thought. OBJECTIVE: To elucidate relevant allergens in this context we studied patients with an informative medical history. METHODS: This report describes a comprehensive allergological approach in a patient exhibiting type-I hypersensitivity-like reactions towards beverages and medication containing alcohol, and salad dressings with acetic acid. RESULTS: The ethanol metabolite acetic acid was found to yield positive prick test results in concentrations not eliciting reactions in healthy and atopic controls. CONCLUSIONS: Among other ethanol metabolites, acetic acid is a potential allergen in the context of hypersensitivity towards alcoholic beverages.