Skin tests traditionally used to predict allergies to amoxicillin, one of the most commonly prescribed antibiotics in children, are ineffective, according to Canadian researchers.
They said oral provocation challenge test, with appropriate follow up, was a more efficient and safer method for diagnosing non-life threatening reactions to amoxicillin.
“Our study suggests that skin tests are essentially useless as diagnostic tests”
The study, published in the journal JAMA Pediatrics, was carried out by a team from McGill University Health Centre in Montreal. The researchers conducted the largest study of its kind to assess the use of a graded challenge in children who presented with a rash due to suspected amoxicillin allergy.
They assessed 818 children who presented to a clinic from March 2012 to April 2015. Unlike previous studies all children had to undergo a graded provocation challenge.
Researchers observed that 94.1% were tolerant to the graded provocation challenge for amoxicillin.
“This is a game changer in the way physicians assess amoxicillin allergy in children”
Among all the study’s participants, only 17 had an immediate positive reaction to amoxicillin, and only one within this group had a positive skin test.
Meanwhile, 31 had non-immediate reactions develop more than one hour after challenge. All non-immediate reactions were described by the researchers as mild and manifested mainly as skin eruptions.
“Our study is the first to determine the percentage of immediate and non-immediate amoxicillin allergy in all children presenting with a suspected amoxicillin induced rash through a graded provocation challenge,” said lead author Dr Moshe Ben-Shoshan.
Skin tests for antibiotic allergies branded ‘useless’
He described the findings as a “game changer” in the way amoxicillin allergy was diagnosed, noting that up to 10% of children developed rashes while on antibiotics.
“The majority are diagnosed without further evaluation as allergic to the implicated antibiotic,” he said. “Most of the patients continue to avoid the suspect antibiotic in favour of alternatives which may be less effective, more toxic, and more expensive.”
“Our study suggests that skin tests are essentially useless as diagnostic tests, and that we should go directly to the graded provocation test that is highly sensitive and specific,” he stated.