Inhaled corticosteroids are the main treatment for controlling asthma in adults and children. However, there is still some concern over the safety of these drugs when used at high doses and for long periods of time. Hence issues relating to the efficacy and safety of inhaled corticosteroids have been extensively researched over the past 5 years. General considerations, such as use of an appropriate dose of inhaled corticosteroid in an appropriate asthma population, are discussed. Studies comparing the efficacy and safety of fluticasone propionate, beclomethasone dipropionate, and budesonide are highlighted, and a systematic review of these studies suggests that fluticasone propionate has a better efficacy:safety therapeutic ratio than either beclomethasone dipropionate or budesonide.