Slow and steady wins: Low-dose peanut immunotherapy safely desensitizes 82% of preschoolers in landmark trial

A groundbreaking three-year Swedish trial reveals that a gentler, slower approach to peanut immunotherapy can transform the lives of allergic toddlers, enabling most to safely tolerate the equivalent of 70 peanuts, while dramatically cutting the risk of severe reactions that have long troubled traditional treatment protocols.

Study: Safety and efficiency of peanut oral immunotherapy in preschool children with slow up-dosing and low maintenance dosing: a randomised controlled trial. Image Credit: triocean / Shutterstock

Preschool Peanut Allergy Treatment Background

Peanut allergy affects nearly 2% of people in Western countries and often begins in early childhood, creating lifelong stress for families worried about accidental exposure and severe allergic reactions.

Safer and more practical treatment strategies are still needed to improve long-term outcomes for children.

Slow Up-Dosing Trial Design

Researchers conducted an open-label randomized controlled trial in Stockholm, Sweden, involving 75 children aged 1-3 years with confirmed peanut allergy. Eligibility was based on positive oral peanut challenge results and detectable Immunoglobulin E antibodies against peanut (Arachis hypogaea 2).

Children with significant uncontrolled asthma, eosinophilic esophagitis, serious medical conditions, or prior life-threatening anaphylaxis requiring intensive care were excluded from the study. Participants were randomly assigned in a 2:1 ratio to receive either peanut oral immunotherapy or peanut avoidance.

The oral immunotherapy protocol used slow dose escalation every 4-6 weeks. Treatment began with approximately one-quarter of each child's reaction threshold, followed by gradual increases until a maintenance dose of 285 mg peanut protein was reached. Peanut flour mixtures were provided in small doses, and larger doses were administered with commercially available peanut puffs (BAMBA). Parents provided daily doses in the home and recorded symptoms, medications, and adherence to the target throughout the three-year study period.

Children underwent repeated oral peanut challenges at 1 and 3 years. A final challenge was performed after 4-6 weeks of peanut avoidance to evaluate sustained unresponsiveness. Blood samples were collected to measure Immunoglobulin E antibodies and Immunoglobulin G4 antibodies against peanut proteins. Adverse reactions, treatment adherence, and allergic disease progression were also analyzed.

Peanut Tolerance and Immune Response Findings

The study demonstrated that slow up-dosing peanut oral immunotherapy with a low maintenance dose produced strong clinical benefits with relatively few serious side effects.

There was a major improvement in peanut tolerance among treated children: 84% had already successfully tolerated the full challenge dose before the peanut-free period began, indicating strong desensitization during ongoing therapy.

The amount of peanut tolerated after treatment was dramatically higher in the oral immunotherapy group. Children receiving therapy tolerated a median cumulative dose of 5000 mg peanut protein, roughly equivalent to 70–80 whole peanuts, while children in the avoidance group tolerated only 3 mg after 3 years, essentially unchanged from baseline reactivity, suggesting little natural resolution of the allergy. In the per-protocol analysis, 35 of 42 children who completed treatment tolerated the full 5000 mg challenge after the peanut-free period.

Notably, the severity of reactions during the final challenge was markedly lower in treated children: only 2.4% experienced grade 5 reactions such as anaphylaxis or breathing difficulties, compared with 25% in the avoidance group. These findings suggest that gradual exposure during early childhood may help the immune system develop lasting tolerance.

Immune markers also changed significantly during treatment. Levels of peanut-specific Immunoglobulin E antibodies and Arachis hypogaea 2-specific Immunoglobulin E antibodies declined over time in treated children, while Immunoglobulin G4 antibodies increased. These shifts indicate that the immune system became less reactive to peanut proteins after prolonged therapy. No similar changes were observed in the avoidance group. However, the study found no significant treatment effect on the development of other allergic manifestations, such as atopic dermatitis, rhinoconjunctivitis, or asthma.

Safety, Adherence, and Dosing Practicality

The safety profile was notably favorable compared with previous oral immunotherapy studies such as IMPACT, POSEIDON, and DEVIL, which enrolled somewhat different populations and used biweekly up-dosing and, in some cases, substantially higher maintenance doses.

The majority of adverse events were mild and included oral itching, lip symptoms, eczema, or urticaria. Of the reported adverse events, only 9% were related to gastrointestinal symptoms; additionally, no child developed any chronic symptoms, as seen in patients with eosinophilic esophagitis.

Severe reactions were uncommon: only 6 children experienced 8 severe dose-related events, and most occurred during the early up-dosing phase. Home administration of epinephrine auto-injectors was required only 3 times in 2 children due to dose-related reactions.

Separately, six children in the treatment group received seven epinephrine doses for reactions after accidental intake of other foods (milk, wheat, or tree nuts), while in the avoidance group, seven children had reactions from accidental peanut exposure, four of which were classified as severe.

Low-Dose Peanut Immunotherapy Implications

The findings showed that peanut oral immunotherapy using slow up-dosing and low maintenance doses can provide high levels of peanut tolerance while minimizing severe allergic reactions in preschool children. Early treatment during a period of greater immune flexibility appeared to improve both effectiveness and safety. The use of commercially available peanut puffs and flexible treatment intervals also increased practicality for families, making long-term adherence easier.

Additional studies comparing therapy schedules and adherence rates among various dosages or treatment protocols are necessary to refine treatment schedules and optimize long-term protection against peanut allergy.

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Journal reference:

• Klevebro, S., Uhl, C., Konradsen, J. R., Ullberg, J., Tedner, S. G., Holmdahl, I., Badolati, I., Da Silva Rodrigues, R., Sverremark-Ekström, E., Nilsson, C., & Asarnoj, A. (2026). Safety and efficiency of peanut oral immunotherapy in preschool children with slow up-dosing and low maintenance dosing: A randomised controlled trial. The Lancet Regional Health – Europe. DOI: 10.1016/j.lanepe.2026.101690, https://www.thelancet.com/journals/lanepe/article/PIIS2666-7762(26)00102-X/fulltext