Oral Food Challenge

An oral food challenge (OFC) is the reference standard for diagnosing Food Allergy. The child eats a suspected food in small, increasing doses at set intervals under medical supervision, with emergency medication and equipment on hand, and staff watch for an allergic reaction. In practice most toddler challenges are open (parent and staff know what food is given). The double-blind, placebo-controlled food challenge (DBPCFC), where the food is hidden and neither side knows whether active food or placebo is given, is used in research, including the primary outcome of the LEAP Trial. The NIAID addendum defines a “specialist” as someone trained to perform and interpret Skin Prick Testing and OFCs and to manage their risks, with medications and equipment on site (Togias 2017).

Oral Food Challenge [defines] Food Allergy LEAP Trial [part-of] Oral Food Challenge

How it works in toddlers. In the NIAID peanut protocol, infants are given a cumulative dose of about 2 g of peanut protein in age-appropriate foods (for example peanut butter thinned into purée). Infants with 3–7 mm SPT wheals should have their first feed as a supervised feeding or a graded OFC in a specialist setting. If there is no reaction, peanut is added to the regular diet. If there is a reaction, strict avoidance is advised and the family receives allergy counselling (Togias 2017). Practical points for 1–4-year-olds include refusal of unfamiliar or disguised foods, the need to hide doses in a familiar vehicle, and the need to have the child’s eczema reasonably controlled first so that the skin can be read. The vault’s sources do not give a standard toddler protocol (dose steps, interval length, observation period), so this is listed as an open question.

Oral Food Challenge [relates] Dual-Allergen Exposure Hypothesis Skin Prick Testing [precedes] Oral Food Challenge

Why it matters in eczema. Up to 53% of children with Atopic Dermatitis have a positive food SPT or Specific IgE Testing result, but only up to 15% react on challenge (JAAD Int 2022). The challenge is what separates true allergy from sensitisation. Chang et al. (2016) reported that practice moved towards doing more OFCs for suspected food-triggered eczema after finding that 19% of children without prior immediate reactions developed new immediate reactions once foods were removed. Of those reactions, 82% were to foods that were being avoided. Challenges therefore protect toddlers from unnecessary Elimination Diets. They can also safely put back foods that a panel test wrongly removed. In the Lack 2003 ALSPAC analysis, peanut allergy was confirmed by challenge in 23 of the 36 children with a reported peanut-allergy history who were tested (Peanut Oil Sensitisation).

Oral Food Challenge [contradicts] Elimination Diets Oral Food Challenge [supports] Peanut Oil Sensitisation

Food-triggered eczema. For delayed, non-IgE eczema flares (worsening hours to days after eating, not within minutes), the usual approach is a short, supervised elimination of the food followed by planned reintroduction. That reintroduction is itself a form of challenge, and it must be planned with a clinician and ideally a dietitian. Braun et al. (2025) stress that the goal is to control the eczema while keeping foods in the diet.

Do not "home-challenge" a food the child has reacted to

Reintroducing a food that previously caused hives, swelling, vomiting or breathing symptoms, or one that has been avoided for months after a positive test, can cause anaphylaxis (Chang 2016). These reintroductions belong in a clinic with emergency treatment available.

Connections

• Food Allergy — diagnostic reference standard, source: NIAID 2017
• LEAP Trial — primary outcome measure, source: Du Toit 2015
• Skin Prick Testing — challenge refutes most AD positives (≤15% of 53%), source: JAAD Int 2022
• Specific IgE Testing — sIgE ≥0.35 kUA/L lacks PPV; refer for challenge, source: NIAID 2017
• Elimination Diets — new immediate reactions after avoidance argue for challenge-guided diets, source: Chang 2016
• Peanut Oil Sensitisation — ALSPAC peanut allergy confirmed by challenge in 23/36, source: Lack 2003
• Dual-Allergen Exposure Hypothesis — supervised feeding for 3–7 mm wheal infants, source: NIAID 2017