Systemic bioavailability from the gastrointestinal tract is reduced with newer inhaled corticosteroids (ICSs) such as fluticasone, but systemic absorption still occurs via the lung. Observational studies have shown an association between ICS use and several adverse outcomes such as cataracts, glaucoma, and adrenal failure, and prospective controlled studies have confirmed a causal relationship between ICS use and bruising, reduction in bone mineral density, and reduced growth velocity. The evidence suggests that the effect of ICSs on bone mineral density is small in the short term but that patients taking moderate or high doses for long periods will be at increased risk of fractures and that this could be an appreciable public health problem. There is also evidence to suggest that the risk of long-term adverse effects is likely to differ between ICSs. The clinical message that follows is that ICSs should be used widely because they reduce the need for courses of oral corticosteroids and improve quality of life, but that they need to be managed carefully to reduce the risk of adverse effects with long-term use.