The safety and efficacy of intranasal corticosteroids (INCs) are well established for the management of allergic rhinitis, rhinosinusitis, and nasal polyps. As seen in numerous studies, INCs demonstrate markedly reduced systemic bioavailability compared with oral and even inhaled corticosteroids and have shown an excellent safety profile over 3 decades of use. Nonetheless, concerns remain among some prescribers and patients that these agents may reach the systemic circulation in sufficient concentration to produce adverse effects (AEs). Available evidence does not support these concerns. A review of the published literature indicates that the side effect profiles of INCs consist primarily of a low incidence of mostly mild and often transient local AEs, such as nasal irritation and epistaxis.The second-generation INC agents currently in use (mometasone furoate nasal spray, fluticasone propionate, ciclesonide, and fluticasone furoate) have favorable pharmacokinetic characteristics that further minimize systemic bioavailability (< 1%) compared with older INCs and compared with oral agents, thereby limiting the risk for systemic adverse events.