The recent article by Busse et al1 on the safety of fluticasone furoate/vilanterol combination (FF/VI) in asthma reported no significant changes in geometric mean 24 h urinary cortisol (24UC) compared with baseline, perhaps giving a false impression that FF is devoid of systemic adverse effects. The interpretation of these data should be put in context of the patients who were already taking inhaled corticosteroids (ICS 500–1000μg/day) and, as such, would have suppressed adrenal function prior to randomisation …