OBJECTIVES: To identify risk factors associated with reactions to peanut following accidental exposure resulting in inpatient (IP) or emergency department (ED) visits. METHODS: Individuals with peanut allergy (PA) were identified from a large US administrative claims database (1999–2017). Continuous health plan enrollment was split into 12-month study periods (patient-years). Report of a diagnosis code of PA or anaphylactic reaction due to peanut in medical claims in an IP/ED setting during a 12-month study period constituted events included in a logistic regression model. These events represent a subgroup of potential reactions to peanut experienced by these individuals with PA (does not include those managed outside an IP/ED setting). This model included factors such as demographic characteristics, comorbidity profile and healthcare resource utilization measured during the pre-12-month study period; odds ratios (OR) and 95% confidence intervals (CI) were reported. RESULTS: A total of 10,959 individuals with PA, representing 55,193 patient-years, were included in the analysis (at the patient-year level: 16% were aged 2-3years, 50% 4–11years, 17% 12–17years, 6% 18-30years, and 10% ≥31years; 42% were female). A total of 1,243 reactions to peanut were observed in an IP/ED setting. Risk factors associated with increased odds of reacting to peanut included: age (adults, particularly young adults 18-30years [OR(95% CI)=3.19(2.66-3.83)]; adolescents 12-17years [OR(95% CI)=1.65(1.41-1.93)]; toddlers 2-3years [OR(95% CI)=1.68(1.42-1.98)]; reference 4-11years), reaction(s) to peanut observed during the previous year (OR[95% CI]=1.66[1.23-2.24]), asthma (OR[95% CI]=1.33[1.18-1.51]), and male gender (OR[95% CI]=1.14[1.01-1.28]) (all p<0.05). CONCLUSIONS: Practice of peanut avoidance is not sufficient to prevent reactions to peanut. Individuals with previous reaction(s) to peanut, asthma and males were observed to have a higher risk in this study focusing on reactions to peanut resulting in IP/ED visits. These factors should be considered in the management of PA and eventually in treatment decision making by healthcare professionals.