The purpose of this review is to provide the clinician with an update on the potential adverse effects caused by the inhaled corticosteroids (ICSs). The systemic effects of ICSs are a result of that portion swallowed and absorbed through the gastrointestinal tract and not eliminated by first-pass metabolism and that portion delivered to the lung and absorbed. If administered in high enough doses, any of the ICSs will produce clinically significant systemic activity. This review will explore the risks for clinically significant adverse effects from sustained use of ICSs, as recommended by the current guidelines. The standard method for assessing systemic activity in short-term studies is measurement of hypothalamic-pituitary-adrenal axis function. The ICSs provided in the medium dose range can produce measurable effects on the hypothalamic-pituitary-adrenal axis. However, clinically significant suppression is unlikely to occur except at high doses. The effect on growth in children over 1 to 4 years occurs at low to medium doses, might be dependent on the specific ICS, and is small (1-2 cm). The data are insufficient to determine whether there is an effect on attainment of predicted adult height. The ICSs affect bone mineral density and risk of fractures in a dose-dependent fashion that appears significant at high doses.