[Penicillin allergy: A label that is not forever].

Self-reported penicillin allergy is highly prevalent. Different studies estimate that 10% of the population is labeled as such. This label, confirmed or suspected, forces us to take precautions and replace the antibiotic treatment of choice (frequently beta-lactams) with other 2nd or 3rd choice alternatives with worse overall results: side effects, resistance, costs, etc. The penicillin allergy label, once placed, remains in the medical record. It is only confirmed in less than 5% of patients, either because it has been placed inappropriately or because over time the sensitivity decreases and may disappear. Penicillin Allergy Decision Rule -PEN-FAST- is a validated and simple clinical prediction rule that estimates the risk of presenting an allergic reaction. Its use, together with algorithms that involve primary care in the study and delabeling of low-risk patients, can change our clinical practice.