Whenever, in the case of a proven IgE-mediated allergy to a BLA, a prolonged treatment with penicillin or another narrow-spectrum BLA is planned and represents the drug of choice from an infectiological point of view (e.g., for daily treatment of neurosyphilis or for prophylaxis of erysipelas with penicillin each day), acute desensitization and then further continuous administration is possible and recommended (in the case of T-cell-mediated reaction, however, desensitization has no reliable effect according to the current knowledge). This evidence concerns the gene IGHE and Allergy.