A peanut allergy diagnosis in infancy can mean years of avoiding the food, but a recent study suggests that more than one-third of babies thought to have the allergy may stop reacting within months of that diagnosis, Live Science reported. In an analysis published in The Journal of Allergy and Clinical Immunology: In Practice, researchers conducted supervised food challenges with infants already diagnosed with a peanut allergy, giving them increasing amounts of peanut protein to see whether they still reacted. "This rate is much higher than we thought," co-author Dr. Timothy Brettig, a pediatric allergist at the National Allergy Centre of Excellence in Australia, told Live Science.
Between April 2024 and October 2025, the team retroactively reviewed records of 1,275 infants referred to Australian public hospitals after a reaction to peanuts before their first birthday. The babies had first been assessed by allergy specialists at a median of 10 months of age. For the initial diagnosis, they needed a history of an allergic reaction and evidence of peanut sensitization on a skin-prick test, a blood test for antibodies, or both. Those tests can hint at sensitization but do not always confirm that a baby will react when eating the food, and they can give false positives. "Children under 1 year of age are an interesting group, as their immune system is still in rapid development and existing allergy tests may not reflect their allergic status well," said Dr. Alexandra Santos, a professor of pediatric allergy at King's College London who was not involved in the study.
Of the 1,275 infants, 778 later underwent a food challenge roughly six months after their first recorded reaction, at a median age of 13 months. They were given up to seven gradually increasing doses of peanut protein, from 15 to 1,300 milligrams, at 15-minute intervals, while medical staff watched for a reaction. Nearly 35 percent, 271 children, completed the challenge without reacting. "The take-home message is to strongly consider a supervised oral food challenge when an infant's peanut allergy diagnosis is uncertain," said Dr. Drew Bird, a pediatric allergist at the University of Texas Southwestern Medical Center who was not involved in the study. He said those challenges should ideally be done before a child starts oral immunotherapy, and that they should be performed by a board-certified allergist-immunologist and an experienced team in a setting equipped to treat anaphylaxis.
The test is not harmless, and it is not something to try at home. In this study, 507 infants reacted during the challenge, and 61 of those developed anaphylaxis and were treated with epinephrine. Santos said that, with infinite resources, almost all patients except those with a history of severe reactions would have a food challenge for diagnosis. Because that is not the case, families of infants whose diagnosis is uncertain may be advised to avoid peanut products while they wait, and in the interim they may miss a window to help the child develop tolerance. She said challenges should be prioritized for infants with uncertain diagnoses, including those with low antibody levels or only small welts on skin-prick tests. Live Science noted that the article is for information, not medical advice.