Flunisolide hydrofluoroalkane (HFA) has efficacy equivalent to that of flunisolide chlorofluorocarbon (CFC) at one third the dose of the CFC formulation, a reduction from 250 microg/puff for flunisolide CFC to 85 microg/puff for flunisolide HFA. Flunisolide HFA delivers a smaller particle size (1.2 microm) in solution, resulting in improved lung deposition as compared with flunisolide CFC (3.8 microm), which is delivered in suspension. An added built-in spacer has reduced oropharyngeal deposition that may result in fewer adverse events and make it easier to use. The objective of this study was to compare the year-long safety of flunisolide HFA (daily dosage 340 microg) with that of CFC beclomethasone dipropionate (BDP) (daily dosage 336 microg) and cromolyn sodium (daily dosage 6,400 microg) in children 4-11 years old with mild-to-moderate asthma. The effects of these drugs on linear growth and growth velocity were also compared. The study was a 1-year open-label, parallel-group trial. Changes in physical examinations (including growth), adverse events, vital signs, electrocardiograms, cosyntropin stimulation tests, mouth and throat cultures for Candida albicans, and laboratory findings were analyzed. Patients 4-5 years old received flunisolide HFA only. In total, 235 children were evaluated (152 receiving flunisolide HFA, 39 BDP, and 44 cromolyn). The incidence of adverse events was comparable among treatment groups; most were mild or moderate and considered unrelated to treatment. Among patients 6-11 years old, mean changes from baseline height at week 52 were 6.2 cm for the flunisolide HFA and cromolyn groups and 5.1 cm for the BDP group. Thus growth in children receiving flunisolide HFA was unaffected by 1 year of treatment. Changes from baseline in other parameters, including response to cosyntropin stimulation, were insignificant and similar among the 3 treatment groups. At the dosages studied, and following 1 year of treatment, flunisolide HFA with its small particle size and built-in spacer is safe and well tolerated in children 4-11 years old. There are no adverse effects associated with hypothalamic pituitary axis (HPA) function of flunisolide HFA, including linear growth in children 6-11 years old when compared with BDP and cromolyn sodium.