Since inhaled and intranasal corticosteroids may be systemically bioavailable, risk of growth suppression cannot be ruled out in children treated with these compounds. The mechanisms by which exogenous corticosteroids can cause growth suppression may be multifactorial, involving influences on growth hormone secretory profiles and insulin-like growth factor-I activity, direct effects on the epiphyseal growth plate, and effects on bone and collagen turnover. When studies on growth in children treated with inhaled and intranasal corticosteroids are interpreted, it is important to discriminate between data on the final outcome of growth (adult height) and data on growth rate. No firm conclusions can be drawn on adult height from the available data. While the data on children treated with inhaled corticosteroids appear reassuring, there are no peer-reviewed studies on the final height of children treated with intranasal corticosteroids. The possibility of additive effects on the final height or growth rate of children receiving intranasal plus inhaled corticosteroids has also not been studied. When assessing the risk of growth rate suppression, specific corticosteroids, doses and inhaler systems must be evaluated separately. Standard paediatric doses of inhaled corticosteroids (budesonide 200 to 400 microg/day delivered from a metered dose inhaler with a spacer, dry powder budesonide 200 microg/day, or dry powder fluticasone propionate 200 microg/day) do not affect growth rate when a twice daily administration regimen is used. The risk of growth rate suppression in children treated with inhaled budesonide depends on the dosage and may become significant with 800 microg/day administered with a spacer, or with 400 microg/day administered with a dry powder device. When high doses of inhaled corticosteroids are used, the risk of adverse effects on growth rate can be reduced by once daily dosage in the morning. In fact, intranasal mometasone furoate 100 and 200microg from an aqueous pump spray and dry powder budesonide 200 and 400microg once daily in the morning have been found not to affect growth rate. Sensitivity to adverse effects on growth rate may vary between individuals. If growth suppression is detected, 'catch-up growth' may be expected when the dose of the inhaled or intranasal corticosteroid is reduced or other treatment modalities are introduced. Inhaled or intranasal corticosteroids should not be withheld from children with asthma or rhinitis. Topical corticosteroids should be given in doses that control disease symptoms; however, height measurements should be performed regularly in children receiving corticosteroids.