BACKGROUND: Peanut allergy causes severe and fatal reactions. Current food allergen labelling fails to address these risks adequately against the burden of restricting food choice for allergic individuals because of limited data on thresholds of reactivity and the influence of everyday factors. OBJECTIVE: We estimated peanut threshold doses for a UK peanut-allergic population and examined the effect of sleep deprivation and exercise. METHOD: In a crossover study, following blinded challenge, peanut-allergic participants underwent three open peanut challenges in random order: with exercise following each dose, with sleep deprivation preceding challenge, and with no intervention. Primary outcome was the threshold dose triggering symptoms (mg protein). Primary analysis estimated the difference between non-intervention challenge and each intervention in log threshold (as % change). Dose distributions were modelled deriving eliciting doses in the peanut-allergic population. RESULTS: Baseline challenges were performed in 126 subjects, 100 were randomized and 81 (mean age 25y) completed at least one further challenge. The mean (SD) threshold was 214 mg (330mg) for non-intervention challenges and this was reduced by 45% (95% confidence interval 21,61 p=0.001) and 45% (22,62 p=0.001) for exercise and sleep deprivation, respectively. Mean (95% confidence interval) estimated eliciting doses for 1% of the population were 1.5mg (0.8,2.5) during non-intervention challenge (n=81), 0.5mg (0.2,0.8) following sleep and 0.3mg (0.1,0.6) following exercise. CONCLUSION: Exercise and sleep deprivation each significantly reduce the threshold of reactivity in people with peanut allergy, putting them at greater risk of a reaction. Adjusting reference doses using these data will improve allergen risk-management and labelling to optimize protection of peanut-allergic consumers.