<jats:title>Abstract</jats:title><jats:sec><jats:title>Background</jats:title><jats:p>Several studies have reported threshold doses for food allergens. However, evidence regarding potential risk factors for low threshold doses is limited. Moreover, the relationship between threshold dose and specific immunoglobulin E (sIgE) levels to causative foods remains unclear. This study examined the relationship and the risk factors for a low threshold dose.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>We recruited children with food allergies and examined the risk factors for a positive oral food challenge (OFC) with a low threshold dose and anaphylaxis.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>We evaluated 2501 children with food allergies (1667 [67%] boys; median age, 4.9 years) to eggs (<jats:italic>n</jats:italic> = 1096), milk (<jats:italic>n</jats:italic> = 671), wheat (<jats:italic>n</jats:italic> = 370), peanuts (<jats:italic>n</jats:italic> = 258), walnuts (<jats:italic>n</jats:italic> = 65), and cashews (<jats:italic>n</jats:italic> = 41). Of these patients, 234 (9%) reacted to ≤30 mg protein of causative foods and 620 (25%) reacted to ≤100 mg protein of causative foods. The sIgE level to causative foods was a significant independent factor for positive OFCs with a threshold dose of ≤30 mg for milk, wheat, and peanuts; ≤ 100 mg for eggs, milk, wheat, peanuts, and cashews; and anaphylaxis from eggs, milk, wheat, peanuts, and walnuts. High sIgE levels to causative foods were associated with a lower threshold dose of the OFC and anaphylaxis during the OFC.</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>Approximately 9% of patients reacted to ≤30 mg protein of causative foods. The potential risks of anaphylaxis should be considered during OFCs for patients with elevated sIgE levels.</jats:p></jats:sec>