Allergic rhinitis (AR) is a major chronic inflammatory disease of the upper airways. AR is increasing in prevalence and causes negative effects on quality of life, impairs performance and productivity, and imposes a serious economic burden. More than 20% of the American population suffers from AR. Intranasal corticosteroids (INS) are an effective and safe first-line treatment for AR, with potent anti-inflammatory properties and a high therapeutic ratio. The systemic bioavailability of the majority of INS is relatively low; however, the pharmacokinetics of absorption, first-pass metabolism, volume of distribution, half-life, and clearance of INS varies considerably, depending on lipophilicity, receptor affinity, and lipid conjugation in the nasal tissue. The short-term (e.g., effect on linear lower-leg growth rate) and long-term (e.g., effect on height) systemic side effects of INS in patients with AR are determined by these important characteristics. AR is present in up to 75% of patients with asthma, and patients with AR are three times more likely to develop asthma compared with patients without AR. Therefore, the overall increased systemic steroid burden resulting from concomitant use of inhaled corticosteroids (ICS) and INS in adult and pediatric patients with comorbid AR and asthma warrants critical monitoring of systemic side effects. This review evaluates the overall safety of INS in AR and the importance of systemic safety considerations of INS, particularly when coadministered with ICS.