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Penicillin allergy often misdiagnosed, say researchers

2025-08-20 HKT 12:40
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Researchers at the University of Hong Kong’s faculty of medicine on Wednesday said people told they are allergic to penicillin should undergo tests as around 90 percent may have been wrongly diagnosed.

This comes after the researchers analysed over 4,700 knee replacement procedures performed at Queen Mary Hospital between 1993 and 2021.

They found that those believed to have a penicillin allergy were five times more likely to develop a periprosthetic joint infection after surgery, leaving them needing further treatment.

The team said during surgical procedures, those thought to have the allergy are given alternatives to penicillin which are less effective and increase their chances of complications.

But actual testing for the allergy is not common, the researchers said, and checks on 11 of the knee surgery patients found they were not allergic to the drug after all.

“Usual people would not feel this is a big issue, as they have been labelled for decades of their life, it hasn’t really affected them. But now we realise even in situations like this, in surgeries and this very common type of surgery [joint replacement surgery], it may affect the outcome,” said Dr Philip Li, who led the research.

“Having this common label does have a bit of a consequence in overall healthcare and the long term outcomes of patients,” he added.

The researchers have launched a pilot scheme at the university’s community pharmacy to allow people to have tests to see if they are allergic to penicillin.

They said the programme has been well-received by patients since its launch last year, and they hope it can be expanded to other community pharmacies in future.

Penicillin allergy often misdiagnosed, say researchers