IgE reactions are reported to be triggered by R1 penicillin side chains in 25% of allergic reactions and the β-lactam ring in 75% of European studies,39 and so there remains a risk that if somebody had an IgE-mediated reaction to the amoxicillin R1 side chain and subsequently tolerated phenoxymethylpenicillin they might be de-labelled but remain at risk of a serious IgE-mediated reaction if exposed to amoxicillin in the future. This evidence concerns the gene IGHE and allergic disease.