Some symptoms (e.g., gastrointestinal intolerance and headache) are falsely considered allergic.(2)Additionally, a skin reaction (e.g., maculopapular or urticarial exanthema) may be due to the interaction between BL and virus, or even be caused by viral infection.(2) Other considerations that may influence the diagnosis are the “low/suboptimal” sensitivity of skin tests, and the natural history of penicillin allergy.(2) There is a natural decrease of IgE antibodies against penicillin over time.(2). This evidence concerns the gene IGHE and Allergy.