The prevalence of cereal allergy is highly influenced by geographical area and consumption habits. According to data from Alergologica 2015 [1], cereal allergy accounts for 2.1% of all cases of food allergy in Spain. Beer is a barley-based alcoholic beverage that also contains hops, yeast, and other cereals (wheat, oats, corn, and even rye). Barley is also the basis of malt vinegar, whiskey, and gin. Several allergens of barley have been described, including lipid transfer protein (LTP), - and ß-amylase, gliadin, glutenin, peroxiredoxin, thionin, and trypsin inhibitor [2].