Beta-lactams (BLs), especially penicillins, are the most commonly used antibiotics, particularly in primary care, and one of the most reported drug allergies. Fearing cross-reactivity, clinicians refrain from prescribing another BL (e.g., cephalosporin or carbapenem) to penicillin-allergic patients. This can have significant consequences for the patients and the health-care system (e.g., exposure to broad-spectrum antibiotics, increased risk adverse effects, and increased healthcare costs).

To assess the absolute cross-reactivity risk, two systematic reviews with meta-analysis were conducted. Then, an approach based on a knowledge mobilization framework considering scientific, contextual and experiential evidences was used. Focus groups with stakeholders, including primary care clinicians, pediatricians, infectious disease specialists and allergists/immunologists, were also held to meet the needs of all actors concerned.

Following this work, it appears that true allergies to penicillin are very rare. Indeed, in patients with a history of penicillin allergy, very few are truly allergic and thus the risk of cross-reaction with another BL is even lower, varying according to structural and physicochemical similarities with alleged-penicillin. Moreover, the risk of having an anaphylactic reaction after penicillin exposure is very low, especially among children. As well, in patients with confirmed penicillin allergy, the observed reactions are usually delayed non-severe skin reactions. However, with a confirmed penicillin allergy, it is important to remain cautious when administering a new BL, especially if the initial reaction was serious or severe. Based on these key messages, a decision aid including an algorithm was developed. Likewise, individualized algorithms for common infections met in primary care were produced.

From this work, health professionals non-specialized in allergology should be able to better manage the risks attributed to penicillin allergies. Therefore, patients should receive the most effective and safe antibiotics to treat their clinical conditions in primary care.