Glucocorticosteroids are the most effective drugs for controlling inflammation of allergic rhinitis (AR). Because of their strong pharmacological action, which can be a so-called ‘double-edged sword’, glucocorticosteroids are usually taken intranasally so as to reduce their potential for eliciting adverse effects. Accumulating evidence suggests that intranasal glucocorticosteroids control not only nasal symptoms but also ocular symptoms. In contrast to sedating H1-receptor antagonists, intranasal glucocorticosteroids can improve impaired performance such as daytime sleepiness associated with AR. In Japanese cedar pollinosis, treatment begun immediately after initiation of pollen release or onset of initial symptoms, known as prophylactic (initial) treatment, is recommended. The current version of the practical guideline for management of allergic rhinitis in Japan recommends the use of chemical mediator release inhibitors, second-generation H1-receptor antagonists, or leukotriene receptor antagonists for prophylactic treatment. However, recent evidence suggests that intranasal glucocorticosteroids might also be useful as first-line drugs for prophylactic treatment. The molecular mechanism of anti-inflammatory action of glucocorticosteroids supports this contention. Moreover, a meta-analysis of studies of intranasal glucocorticosteroids given as monotherapy has revealed that these agents are superior to oral H1-receptor antagonists and leukotriene antagonists for controlling major symptoms of AR. These findings suggest that glucocorticosteroids, especially intranasal glucocorticosteroids, might be positioned as first-line drugs for the treatment of both perennial and seasonal AR.