Removing incorrect penicillin allergy labels on GP records could combat antibiotic resistance and save lives, an NIHR-funded clinical trial led by the University of Leeds has found.
Penicillins are first-choice antibiotics for many common infections, but more than one in 15 UK adults have a penicillin allergy label on their medical records. In the event of an infection, they will be prescribed alternative antibiotics which can be less effective or have more side effects. This can result in several prescriptions being issued to control the infection, which affects wellbeing and contributes to antimicrobial resistance.
The global challenge of antibiotic resistance is causing people to die of common infections – so it is vital to find ways to improve how antibiotics are used.
But the results of the largest UK clinical trial of its kind, funded by the National Institute for Health and Care Research (NIHR) and published in the Lancet Primary Care, showed that almost nine in ten (88%) patients with a penicillin allergy label were not truly allergic after testing, and had their allergy label safely removed. More than 800 patients were included in the trial.
Allergy mislabelling can happen when infection symptoms are mistaken for allergies, or when true allergies disappear over time. Verifying the accuracy of penicillin allergy labels could help patients to access more effective antibiotics, which is crucial as the threat of antimicrobial resistance to public health grows. The ALABAMA (ALlergy AntiBiotics And Microbial resistAnce) trial, coordinated by the University of Oxford Primary Care Clinical Trials Unit, was created to help find solutions for this issue.
To mark the publication of the results, joint lead author Sue Pavitt – Professor in Translational and Applied Health Research in the School of Dentistry at Leeds – is speaking publicly for the first time about her mother Rosie, who died aged 91 of an antimicrobial resistant infection after having a penicillin allergy on her records for decades.
This research is in part her legacy and shows the value of preserving antibiotics.
Rosie Woollard had a penicillin allergy label added to her medical records in 1956. She was prescribed penicillin as a result of mastitis, a common breastfeeding infection – but when she developed a rash, she was told to avoid penicillin.
Her daughter Professor Pavitt said: “My mum was vigilant and avoided taking penicillin from that day, but her allergy was never checked. It may have been a simple reaction to the other substances used in manufacturing the tablet or her rash was just a consequence of the infection.”
Joint lead author Dr Jonathan Sandoe, Associate Clinical Professor in Microbiology in the University of Leeds School of Medicine and Leeds Teaching Hospitals NHS Trust, said: “Antibiotics have been life-saving drugs since the late 1930s, but we are now in an era where microbes are evolving to resist the effects of current antibiotics. The global challenge of antibiotic resistance is causing people to die of common infections – so it is vital to find ways to improve how antibiotics are used. Assessing people with penicillin allergy labels is one way we can achieve this.”
‘Each round of antibiotics took a toll’
Professor Pavitt said: "When my mum got older and had more underlying health problems, we noticed that when she had an infection, she often needed two or three courses of different antibiotics before the infection would clear. Each round of antibiotics took a toll on her wellbeing, appetite and ability to bounce back until the infection was under control."
Professor Pavitt says Rosie used to believe she was getting “better” antibiotics as they were more expensive. “What she didn’t realise was that penicillins are one of the most highly effective types of antibiotics that work against many common infections and so she was arguably not receiving the best recommended treatment. And those antibiotics that were not working were likely contributing to her growing more resistant strains of bugs.”
Later in life, Rosie developed repeated urinary bladder infections, until she contracted one the antibiotics couldn’t control just days after her 91st birthday. She died shortly afterwards, and her cause of death was recorded as an antimicrobial resistant infection on her death certificate.
Rosie’s research legacy
Sue holds Rosie’s hand at the end of her life. Credit: Sue Pavitt.
Professor Pavitt said: “Mum was always interested in my research – working with Jon Sandoe and me since she was in her 80s. Antibiotic allergy and resistant bugs are complex concepts to understand – she was our barometer to see if we were explaining things clearly.
“She was also instrumental in making the ALABAMA trial open to older people with multiple long-term conditions, a group that is often excluded from research but important to reach.
“This research is in part her legacy and shows the value of preserving antibiotics, so that we can keep fighting infections with these important medicines.”
Bernard Woollard, Rosie’s son and Sue’s brother, added: “My eldest daughter also has a penicillin allergy label. I am delighted that in the future she may gain real help as a direct result of the ALABAMA trial.”
Widespread testing needed
Penicillin allergy testing is not yet widely available across the NHS, but the research team are working with colleagues in the NHS to plan how to widen access to penicillin allergy assessment for patients. If patients need treatment for an infection and have a penicillin allergy label they should speak to their GP about the best treatment.
Although the findings show that penicillin allergy testing is cost-effective, there are limited numbers of immunology and allergy specialists available to carry it out on a wider scale. This means it would be almost impossible to check all patients with penicillin allergies within the NHS at the moment.
Dr Sandoe added: “This research shows that removing incorrect penicillin allergy labels has the potential to improve patient experiences, reduce health costs and tackle bacterial resistance. Now, we need to work together with policymakers and patients to help the NHS to address this issue.”
Rosie was a patient public contributor for ALABAMA, helping the researchers to make the trial more accessible to potential participants.
Reducing preventable harm
The 823 patients included in the trial had no history of serious adverse reactions to penicillin. Participants were recruited from 51 general practices in four regions of England, and testing was carried out at four NHS hospital trusts. They were randomly assigned to be part of the allergy checking group or the control group, who continued with regular care without having an allergy check.
Participants who underwent penicillin allergy checks received fewer antibiotics overall. When patients had their allergy label safely removed after allergy testing, GPs were five times more likely to prescribe them a first-choice penicillin antibiotic when they needed treatment for common infections.
To test participants’ allergies, they either had a dose of a penicillin by mouth or first had a small injection of penicillin under the skin and then had a dose of oral penicillin. If there was no immediate reaction, patients then took three days worth of penicillin at home, and were monitored by the research team for delayed reactions. Eight per cent of participants had a positive test and kept their penicillin label, but none had a serious reaction.
Co-author Christopher Butler, Professor of Primary Care in the Nuffield Department of Primary Care Health Sciences at the University of Oxford, said: “This innovative and timely study proves the principle that there are feasible, implementable ways of having people safely delabelled as penicillin allergic, and that this means they are able to receive more appropriate care when they next get an infection.
“It’s this kind of research question that has a huge impact on improving care for individuals, improving cost-effectiveness of what we do as clinicians, and helps us preserve the precious shared resource of antibiotics to all of us and to future generations.”
The ALABAMA (ALlergy AntiBiotics And Microbial resistAnce) trial was coordinated by the University of Oxford Primary Care Clinical Trials Unit with support from the NIHR Leeds Biomedical Research Centre and the NIHR Clinical Research Facility at Leeds Teaching Hospitals NHS Trust.
Further information
Email University of Leeds Press Officer Mia Saunders at m.saunders@leeds.ac.uk with media enquiries.
Top image credit: Bernard Woollard.
Penicillin allergy assessment pathway versus usual clinical care for primary care patients with a penicillin allergy record in the UK (ALABAMA): an open-label, multicentre, randomised controlled trial is published in the Lancet Primary Care on Monday 14 July 2025. The authors were: Jonathan A T Sandoe, Shadia Ahmed, Kelsey Armitage, Chris Bates, Rebecca Bestwick, Jenny Boards, Christopher C Butler, Johanna Cook, Joanne Fielding, Ushma Galal, Philip Howard, Daniel Howdon, Sam Mort, Ruben Mujica-Mota, Alina Negut, Catherine E Porter, Neil Powell, Marta Santillo, Ravishankar Sargur, Sinisa Savic, Sarah Tonkin-Crine, Marta Wanat, Robert M West, Miaoqing Yang, Ly-Mee Yu, and Susan H Pavitt, on behalf of the ALABAMA Trial Research Group.