Penicillin allergy overdiagnosed: new Australian guidelines Urge reassessment for millions

ASCIA updates advice after evidence shows 90% of reported allergies are incorrect

By LineZotpaper

Published21 October 2026

Updated21 October 2026

Read Time2 min

Sources2 outlets

The Australasian Society of Clinical Immunology and Allergy (ASCIA) has published revised guidelines revealing that the majority of Australians labeled with penicillin allergy are not truly allergic. The change, based on new evidence, aims to improve patient care, reduce healthcare costs, and combat antimicrobial resistance by ensuring appropriate use of narrow-spectrum antibiotics.

The article from The Guardian explains that penicillin allergies were thought to affect 10% of Australians, or around 2.8 million people. However, up to 90% of these reports may be incorrect. This misdiagnosis stems from various factors, such as mistaking side-effects like rash or nausea for allergies, doctors recording side-effects as allergies out of caution, or long-held diagnoses from childhood that were never reassessed.

Clinical immunologist Professor Michaela Lucas from the University of Western Australia noted that accurate diagnosis is crucial. Penicillin is a narrow-spectrum antibiotic effective against common infections, and avoiding it forces the use of broader antibiotics that can harm gut bacteria and promote superbugs. "Antimicrobial resistance matters beyond the individual patient, because resistant bacteria can spread between people and through communities," she said, warning of limited treatment options if bacteria become resistant.

Dr Nick Cooling, chair of the Royal Australian College of General Practitioners' allergy special interest group, welcomed the guidelines. He pointed out that patients with a penicillin allergy label tend to have longer hospital stays and higher costs due to more treatments and side-effects. "The ability to clarify that with these patients will reduce hospital costs but also the whole health system cost," he said. He urged patients to discuss their reported allergy with their GP, but warned against self-testing.

For families like Tammy Prescino's, the issue is urgent. Her 70-year-old mother and 12-year-old daughter both carry a penicillin allergy diagnosis. Prescino plans to seek reassessment, because if they are not truly allergic, they could benefit from penicillin treatment when needed.

Analysis

Why This Matters

Up to 2.8 million Australians may be wrongly labeled as penicillin-allergic, leading to unnecessary hospital stays and costs.
Overuse of broad-spectrum antibiotics due to misdiagnosis contributes to antimicrobial resistance and superbug growth.
Revised guidelines could improve individual patient outcomes and reduce burden on healthcare systems.

Background

Penicillin is a commonly used antibiotic in Australia, and allergies were reported by 10% of the population. New evidence suggests up to 90% of these reported allergies are not genuine, often due to confusion with side-effects. The ASCIA guidelines provide the first peer-reviewed update for healthcare professionals on diagnosis and management.

Key Perspectives

Medical experts (Prof Michaela Lucas): Misdiagnosis arises from cautious clinicians, side-effect confusion, and inherited labels. Correct labeling is key to preserving antibiotic effectiveness.
General practitioners (Dr Nick Cooling): GPs play a critical role in reassessing penicillin allergies, which can reduce healthcare costs and hospital stays. Self-testing is dangerous and should be avoided.
Patients and families (Tammy Prescino): There is concern that current labels may prevent access to effective treatments. Patients want accurate assessments to ensure best care.

What to Watch

Adoption rate of new guidelines by GPs and specialists.
Changes in hospital admission data for patients with penicillin allergy label.
Impact on antimicrobial resistance rates as narrow-spectrum antibiotics gain use.

Sources

Majority of Australians who report penicillin allergy not truly allergic · World news | The Guardian
Majority of Australians who report penicillin allergy not truly allergic · Australia news | The Guardian

Checked

12 claims in this story checked against 1 source: 7 supported.

Show each claim

Partly supportedThe summary says 90% of reported penicillin allergies are incorrect.Australia news | The Guardian: “But the latest evidence shows up to 90% of those reporting a penicillin allergy do not have one.”
SupportedASCIA has issued revised guidelines after evidence showed most people reporting penicillin allergy are not truly allergic.Australia news | The Guardian: “The majority of Australians who report a penicillin allergy are not truly allergic, prompting the peak body for immunologists to change its guidelines”
SupportedThe guidelines urge reassessment for millions of Australians.Australia news | The Guardian: “Cooling urged affected patients to raise the question of a penicillin allergy with their GP”
Partly supportedThe guidelines aim to improve patient care, reduce healthcare costs and combat antimicrobial resistance.Australia news | The Guardian: “prompting the peak body for immunologists to change its guidelines in a bid to reduce hospitals stays and tackle antimicrobial resistance.”
SupportedPenicillin allergy was thought to affect 10% of Australians, or about 2.8 million people.Australia news | The Guardian: “Penicillin, one of the most commonly prescribed antibiotics in Australia, was thought to cause allergies in 10% of Australians, or about 2.8 million people.”
Not in the sourcesLucas said accurate diagnosis is crucial.
SupportedLucas said resistant bacteria can spread between people and communities.Australia news | The Guardian: ““Antimicrobial resistance matters beyond the individual patient, because resistant bacteria can spread between people and through communities,” Lucas said.”
Partly supportedLucas warned that bacteria becoming resistant could leave doctors with limited treatment options.Australia news | The Guardian: ““If someone develops a serious infection that is resistant to several antibiotics, doctors can be left with very limited treatment options.””
SupportedCooling said clarifying allergy labels will reduce hospital and health-system costs.Australia news | The Guardian: ““The ability to clarify that with these patients will reduce hospital costs but also the whole health system cost,” he said.”
SupportedCooling urged patients to discuss their reported allergy with a GP and warned against self-testing.Australia news | The Guardian: “Cooling urged affected patients to raise the question of a penicillin allergy with their GP, and with cases where the potential risk of harm is low, doctors could give their patient penicillin and monitor for symptoms. But he warned: “No one should try taking penicillin themselves to find out whether they are allergic.””
SupportedPrescino plans to seek reassessment for her mother and daughter, who have penicillin allergy diagnoses.Australia news | The Guardian: “She welcomes the changes, with her 70-year-old mother and 12-year-old daughter both diagnosed. Prescino worries that if her mother were to get an infection, she could miss out on the benefits of penicillin. She plans to see a doctor and to get her family reassessed.”
Partly supportedPrescino’s mother and daughter could benefit from penicillin treatment if they are not truly allergic.Australia news | The Guardian: “Prescino worries that if her mother were to get an infection, she could miss out on the benefits of penicillin.”