New penicillin allergy research – does penicillin allergy last forever?

A common question facing one in 10 Australians is whether their penicillin allergy will last forever.

What does this research show?

This research shows that a simpler way of testing people who are very unlikely to have a true penicillin allergy is safe and effective.

What does this mean for me?

In the future, testing may become easier to do and easier to access for people who have been labelled with penicillin allergy, but are unlikely to be truly allergic.

A world-first randomised control trial, the Penicillin Allergy Clinical Decision Rule (PALACE) study, has shown promising results in the field of penicillin allergy testing. Penicillin allergy is a common public health concern, with one in 10 patients being documented as having a penicillin allergy. Yet, when testing is available, fewer than 10% of those labelled with a penicillin allergy are truly allergic. It is very important to find out whether a person has a true penicillin allergy. People with a documented penicillin allergy are more likely to be prescribed alternative antibiotics, known as second-line antibiotics, which are often not as effective against certain infections. This can lead to longer treatment times, the treatment not working and the development of bacteria that are not easily killed by standard antibiotics.

Many people who had a reaction to penicillin as children don’t undergo testing for their allergy. Research has shown that 80% of people who have had a penicillin allergy are not allergic when they are tested 10 years later. The current way to test for penicillin allergy can be painful, take a lot of time or is not widely available, making it difficult for people to access.

The PALACE study aimed to look at these issues by investigating whether a simpler way of testing people with low-risk penicillin allergy is safe and effective.

The study was undertaken by a team of researchers from specialised centres in North America and Australia – including lead author Ana-Maria Copaescu and senior author Professor Jason Trubiano from the Centre for Antibiotic Allergy and Research, Department of Infectious Diseases at Austin Health.

The study enrolled 382 adults who were assessed as ‘low risk’ using a tool to check that they were very unlikely to have a severe reaction. They were then randomly put into 2 groups. One group received a simple oral test called a ‘direct oral penicillin challenge’, while the other group received the standard approach of penicillin skin-testing followed by an oral challenge.

The study found that only one patient (0.5%) in each group was shown to be allergic to penicillin on the day of the challenge in clinic. After the challenge, more than 95% of patients in both groups had no reported reaction 5 days later. This shows that the direct oral penicillin challenge without skin-testing is just as effective as the standard method in patients with a low-risk allergy. Importantly, it was shown to be safe, as there were no significant differences in adverse events between the 2 groups, and no life threatening events were reported.

The PALACE study means that direct oral penicillin challenge may be a safe and effective alternative to traditional skin-testing. This could mean that penicillin allergy testing may become easier for people to access in the future. Patients should discuss with their GP if they are suitable for referral for penicillin allergy testing.

Read more on the Centre for Antibiotic Allergy and Research website.