In 2012, it was estimated that nearly 1 in 4 Canadians suffer from allergic rhinitis. To add,
78% of individuals working in predisposing environments are predicted to develop occupational
rhinitis. Currently, the most popular treatment for rhinitis is antihistamine medication such
as diphenhydramine, a first-generation antihistamine sold commercially as Benadryl®. Due it
its anticholinergic effects, diphenhydramine has been suggested to impair the whole body
sweating response during heat stress, potentially leaving consumers at an increased risk of
heat-related illness. This randomized control trial approved by Health Canada will
investigate whether ingesting extra strength diphenhydramine (50mg) will alter whole-body
sweat losses during 60 minutes of exercise.