Penicillin allergy delabelling (PADL) has become a critical focus in antimicrobial stewardship as many penicillin allergy records are inaccurate and can lead to unnecessary harm. Amid the limited availability of allergists, PADL pathways led by pharmacists, nurses and primary care teams have been implemented across various settings in Cornwall, UK. This case study describes these approaches, shares early results and reviews emerging evidence on the effects of delabelling.
Penicillin allergy delabelling (PADL) is now recommended as a key antimicrobial stewardship intervention by several international organisations and there are multiple national and international guidelines to support healthcare professionals to safely delabel patients.1–5
While penicillin allergy records are common, most are incorrect and research has shown that more than 95% of these patients can safely take penicillin after formal allergy testing.6,7
Inaccurate penicillin allergy records are associated with several negative patient, healthcare system and wider societal outcomes, which are thought to be due to prescribing more broad-spectrum non-penicillin alternatives.8
The paucity of allergists in the UK and globally has prompted non-allergist healthcare professionals to explore PADL, and a recent systematic review of the literature found that clinicians, pharmacists and nurses can safely deliver PADL using several models of care.9
The majority of studies identified patients with a low-risk allergy record and delabelled them after an oral test dose of a penicillin – known as a direct oral challenge (DOC) and usually using amoxicillin – or after penicillin allergy history reconciliation, which is known as a direct delabel (DDL).
Low-risk penicillin allergy histories suitable for a DOC include non-severe skin reactions that occurred more than 10 years ago or unknown reactions from over a decade ago that lack severe features, such as hospitalisation, adrenaline requirement, blisters or desquamation.
For a DDL, low-risk histories include intolerances such as nausea, vomiting and other mild symptoms not indicative of drug allergy, as well as patients who tolerated penicillin after the initial reaction, provided their allergy history was low risk and met DOC criteria. In such cases, subsequent exposure serves as a DOC. It is worth noting that testing protocols vary across the literature.10
Pharmacist-led inpatient penicillin allergy delabelling
The recently completed REPeAL study developed and tested an inpatient PADL implementation intervention at a single hospital in the south-west of England.11
The intervention included components to facilitate and support doctors and pharmacists in delivering inpatient PADL, including education, expert advice from infection specialists, a named PADL champion, hospital-endorsed PADL guidelines with the necessary tools to enable PADL, and patient information leaflets. The intervention was deployed at the study hospital on 11 June 2024.
At the time of writing, the final manuscript reporting the first six months of outcomes has yet to be published. However, our routinely collected data show that, as of December 2025, 851 inpatients have been risk-assessed, of whom 372 (43.7%) were successfully delabelled: 124 (33.3%) via DOC and 248 (66.7%) via DDL.
Nurse-delivered outpatient penicillin allergy delabelling
Outside the UK, patients have been successfully delabelled by non-allergy-trained doctors, nurses and pharmacists in outpatient clinics.13 For example, the Hong Kong Drug Allergy Delabelling Initiative – a nurse-led, low-risk outpatient clinic supported by physicians without allergist review – successfully delabelled 56 patients after DOC.14
In our process evaluation of the REPeAL implementation, some patients told us that it was not the right time to be tested while they were acutely unwell inpatients, but they would agree to testing in the outpatient setting once they had recovered from their illness.
We therefore implemented a nurse-led, adult low-risk PADL outpatient clinic, supervised by an antibiotic pharmacist, and invited referrals from hospital outpatient departments and three local GP surgeries.
Telephone triage of patients began on 6 January 2025, including taking a penicillin allergy-focused history, risk-assessing the allergy history, and determining the PADL method, if appropriate.
Between 27 December 2024 and 16 September 2025, we received 400 referrals, of which 327 patients were successfully contacted by telephone, and their allergy history was taken and risk stratified by a clinic nurse.
Of these, 190 were categorised as low-risk, with 21 patients (11.1%) delabelled by DDL over the phone, and 110 of 115 (95.7%) tested by DOC in the outpatient clinic were successfully delabelled.16
Prescribing and medicine optimisation scheme
The prescribing and medicine optimisation scheme (PMOS)is an incentive scheme administered by integrated care boards (ICBs). It aims to incentivise general practices to take part in delivering work expected to have a patient benefit.
The Cornwall and Isles of Scilly ICB adopted a bespoke PADL scheme developed by the local medicines optimisation prescribing team. Training was delivered to prescribing leads in each GP surgery, and the PMOS scheme commenced in April 2025.
Participating practices were tasked with searching GP care records to identify patients with a recorded penicillin allergy who had received a penicillin antibiotic after the allergy was recorded.
The scheme will conclude in March 2026, and the number of patients successfully delabelled will be reported. However, a recent unpublished survey of GP practices demonstrates widespread adoption of the scheme, with 26 of 27 (96%) responses from GP surgeries indicating that they have completed the task or will complete it by March 2026.
The penicillin allergy delabelling ALABAMA and iNAAN trials
To date, few prospective studies have examined the effects of PADL, and evidence that delabelling reverses associated harms remains limited. Two recent prospective studies were designed to assess the impact of PADL on patient outcomes.
The ALlergy AntiBiotics And Microbial resistAnce (ALABAMA) trial was a UK multicentre, open-label, pragmatic outpatient PADL study that was initially designed with treatment response failure as the primary outcome, but this was changed to penicillin prescribing due to slow recruitment.17
All participants had a record of penicillin allergy or sensitivity in their electronic medical record, had received an antibiotic prescription in the previous 24 months and were outpatients at the time of recruitment.
A total of 411 patients were randomised to the penicillin allergy assessment pathway and were delabelled if deemed safe to do so. A further 412 patients were randomised to usual clinical care without delabelling. The prescribing of penicillin was five times higher among those who were delabelled than in the non-delabelled group, suggesting that delabelling can increase the prescription of narrow-spectrum penicillins.
The International Network of Antibiotic Allergy Nations (iNAAN) study is a prospective, multicentre international study conducted in 40 hospitals across eight countries.18 Using the target trial emulation design, 892 participants received inpatient penicillin DOC and 960 participants were only assessed and retained their allergy label (controls).
DOC was associated with a 13-fold increase in penicillin use, a 1.4-fold reduction in prescribing World Health Organization ‘Watch’ or ‘Reserve’ antibiotics and accelerated the switch from intravenous to oral antibiotics.19
Inpatient penicillin DOC was associated with a lower rate of acquisition of multidrug-resistant Gram-negative bacteria within 90 days of evaluation (relative risk, 0.57; 95% CI 0.33–0.99; p = 0.046) but was not associated with a difference in acquisition of other multidrug-resistant organisms, or change in length of stay for the index hospital stay.19
Site recruitment and data collection for iNAAN continues, with further analysis planned as case numbers increase to determine whether PADL has any impact on other patient, health system and antimicrobial resistance outcomes.
Conclusion
In line with NHS England’s ambitions, Cornwall has made a comprehensive start on PADL across multiple healthcare settings and through a range of care models. The ongoing challenge is sustaining this work within limited resources.
Authors
Neil Powell MPharm
Consultant antimicrobial pharmacist and associate director, antimicrobial stewardship
Michael Wilcock MPhil
Head of the prescribing support unit
Daniel Hearsey
Advanced specialist clinical pharmacist
All of Royal Cornwall Hospitals NHS Trust, UK
References
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12 Powell N et al. Description of the combined evidence based, theory-based and person-based approaches used to develop a behavioural intervention package to support non-allergist healthcare workers to remove incorrect penicillin allergy records from medical and surgical adult inpatients in a UK hospital. BMJ Open 2025;15(7):e096452.
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18 Mitri E et al. International Network of Antibiotic Allergy Nations (iNAAN): Protocol for a type 2 hybrid effectiveness-implementation multicentre prospective cohort and target trial emulation study evaluating penicillin allergy delabelling via direct oral challenge. PLoS One 2025;20(9):e0330724.
19 Powell N. Personal communication, January 2026.
