I obediently recite that I am allergic to penicillin every time I am asked for my medical history. But why do I think this? During a period of repeated antibiotic prescription, I experienced unpleasant side-effects—headache, rash, stomach upset—that got worse with each antibiotic prescription. I reported these to my GP and my family history of penicillin allergy.

So what happened next? Allergy testing? No. The GP simply typed into my medical records that I was allergic to penicillin. And that was that.

Globally we are labelling people as penicillin allergic without confirmatory tests

In the US 10% of the population is listed as penicillin allergic.¹ A combination of a lack of access to allergy testing in high, middle and low income countries, and a lack of knowledge to distinguish between a one-off bad reaction to a drug compared with a true allergic reaction, leads many primary-care physicians err on the side of caution—not wanting to expose their patient to a potentially severe reaction—by labelling their patient as allergic without official confirmation.²

Global estimates are that as many as 90-99% of people who are labelled with a penicillin allergy are, in fact, not penicillin allergic.^3,4,5

The main reasons people may be incorrectly labelled are that either people have experienced side-effects that presented like, but were not a true allergic reaction or they have grown out of their allergy.⁶ In the US, the label of penicillin allergy in children is applied before the age of three in an estimated 75% of cases and often without a physical examination.⁷ Even among those who have experienced a true allergic reaction, approximately 80% of people lose their sensitivity within a decade—meaning they could take penicillin again in the future.^8,9

So what are the consequences of unconfirmed penicillin allergies?

People who are labelled as penicillin allergic have access to a reduced range of antibiotics, meaning that they can be more prone to infections, at greater risk of developing antibiotic-resistant infections, have longer hospital stays and higher inpatient costs.^10,11

What can we do about these large numbers of people labelled with an unconfirmed penicillin allergy?

The World Health Organisation has declared antimicrobial resistance (AMR) one of the top ten global public-health threats facing humanity and endorsed de-labelling people assessed as low-risk for a serious reaction as an effective component of AMR policy.^12,13,14 In October 2023, the British Society for Allergy and Clinical Immunology published new guidelines on how to set up a de-labelling service within a hospital that can be managed by non-allergy specialists.¹⁵ Multi-disciplinary approaches that are not reliant on allergy specialists are invaluable in de-labelling protocols given the number of incorrectly labelled penicillin allergies, the resulting poorer outcomes and a worldwide lack of access to specialist testing.^16,17

Penicillin-allergy de-labelling as an AMR strategy

As the world continues to struggle with managing AMR, de-labelling offers a practical measure to reduce the risk of antibiotic-resistant infection among the large numbers of people globally who are incorrectly labelled as penicillin allergic. This benefits the individuals with incorrect penicillin-allergy labels and health systems—both of which bear the cost.

The main issue is that currently de-labelling is a small-scale, localised solution to a global problem. But studies have shown great promise in terms of clinical outcomes and patient satisfaction, even with small sample sizes, such as integrating de-labelling into existing surgical pathways.^18,19,20

So how do we translate localised pilot schemes into large-scale programmes and global policy? Has your health system implemented de-labelling protocols? Let’s continue the conversation on LinkedIn.