More than one in three infants believed to have a peanut allergy showed no reaction when they later underwent a supervised oral food challenge, according to an analysis published in the Journal of Allergy and Clinical Immunology: In Practice. The findings suggest that some babies diagnosed after an initial reaction may not have a persistent allergy, although food challenges can trigger serious reactions and must be conducted by specialist medical teams.
Many infants tolerated peanut protein
Researchers retrospectively reviewed the medical records of 1,275 infants referred to public hospitals in Australia after experiencing a reaction to peanuts before their first birthday. The babies were initially assessed by an allergist at a median age of 10 months. The records covered referrals made between April 2024 and October 2025.
Of those infants, 778 underwent a supervised oral food challenge about six months after their first recorded allergic reaction. Their median age at the challenge was 13 months.
During the procedure, the infants received up to seven increasing doses of peanut protein, ranging from 15 to 1,300 milligrams. The doses were given 15 minutes apart while medical staff monitored the children for symptoms.
In total, 271 children—almost 35% of those who completed the challenge—had no reaction to the peanut protein. The researchers described this rate as much higher than expected.
“This rate is much higher than we thought,” study co-author Dr. Timothy Bretig, a pediatric allergist at Australia’s National Allergy Center, told Live Science.
Why an infant allergy diagnosis can be uncertain
The initial diagnosis required both a history of an allergic reaction to peanuts and evidence of peanut sensitization in allergy testing. The tests included a skin-prick test, in which peanut extract is placed on the skin before it is lightly pricked to look for a local reaction, and a blood test that detects antibodies against peanut protein.
However, sensitization does not always mean that a baby will experience an allergic reaction after eating the food. Tests can also produce false-positive results.
“Children under one year of age are an interesting group because their immune systems are still rapidly developing and existing allergy tests may not fully reflect their allergic status,” said Dr. Alexandra Santos, a professor of pediatric allergy at King’s College London who was not involved in the study.
In other words, a test may show that a child is sensitized to a food without confirming that the child has a clinical allergy. An incorrect diagnosis can lead families to avoid peanuts unnecessarily and may prevent children from being exposed to the food under appropriate medical guidance.
Food challenges must be medically supervised
Of the 778 infants who underwent a food challenge, 507 reacted to the peanut protein. Sixty-one of those children developed anaphylaxis and were treated with epinephrine, the hormone used in EpiPens.
For that reason, an oral food challenge should be performed by a board-certified allergist-immunologist and an experienced allergy team in a setting equipped to treat anaphylaxis, a serious and potentially life-threatening allergic reaction.
“This is a great article,” said Dr. Drew Bird, a pediatric allergist at the University of Texas Southwestern Medical Center who was not involved in the study. “The key message is to strongly consider a supervised oral food challenge if the diagnosis of peanut allergy in an infant is uncertain.”
Bird said these challenges should ideally take place before a child begins oral immunotherapy. Oral immunotherapy involves regularly consuming carefully measured amounts of an allergenic food, with doses gradually increased under a doctor’s supervision. The aim is to help the patient tolerate larger amounts of the allergen and reduce the risk from accidental exposure.
Oral food challenges are also often used to determine the starting doses for oral immunotherapy. In principle, the challenge can therefore help establish whether a child needs treatment in the first place.
Balancing caution with early exposure
“In an ideal world with unlimited resources, all patients except those with a history of severe reactions would be placed on a restricted diet for diagnosis,” Santos said.
Because resources are limited, families of infants with an uncertain diagnosis may be advised to avoid peanut products while they wait for a formal food challenge. Santos cautioned that delaying exposure may miss an opportunity to build tolerance and could increase the risk that an allergy persists.
She said food challenges should be prioritized for infants whose diagnosis is uncertain, including babies with low levels of peanut-specific antibodies in their blood or only small welts on a skin-prick test.
The study was published in 2026 under the title: Bretig, T. W., McDonald, E., West, D., et al. “Prior to oral immunotherapy, an oral food challenge test is required to accurately diagnose peanut allergy in infants: Assessment of Allergy Development to Accelerated Pathways to Tolerance Peanut Oral Immunotherapy Program.” Journal of Allergy and Clinical Immunology: In Practice.
This article is for informational purposes only and does not provide medical advice.
Source: www.livescience.com