Urticarial reaction caused by ethanol.

BACKGROUND We report a case of an urticarial reaction after drinking alcohol beverages. The patient was a 47-year-old man suffering urticarial and anaphylactoid reaction to alcohol for two years. These reactions were observed at every alcohol beverages intake. CASE SUMMARY We performed a prick test with diluted ethanol, alcohol beverages and their metabolites (acetaldehyde, acetic acid). Only acetic acid showed a positive result. Oral challenge test with diluted-ethanol caused pruritus and swelling of his lips. An oral challenge test with 8% diluted Shochu (Japanese distilled alcohol from rice or wheat) caused wheals on his upper back. DISCUSSION Only acetic acid, a metabolite of alcohol, induced a positive prick test in the patient with alcohol-induced urticaria. This result was not observed in normal volunteers. An oral challenge test with diluted-alcohol or Shochu showed a positive wheal reaction in a dose dependent-manner which suggests that urticaria seen in this patient might be induced by alcohol-intolerance. However possible allergic reaction to acetaldehyde could not be excluded.