Aims: To demonstrate the noninferiority of extrafine beclomethasone/formoterol fumarate (BDP/FF) dry powder inhaler (DPI) vs. extrafine BDP/FF pressurized metered dose inhaler (pMDI; Foster® 100/6 μg NEXThaler and pMDI, respectively) in the onset of reliever effect after methacholine induced bronchospasm in asthmatic patients, evaluated in terms of forced expiratory volume in 1 s (FEV1) at 5 min postdose. The DPI provides an alternative device option for patients who cannot use a pMDI properly during an acute asthma attack. Methods: Sixty-five patients received one inhalation of BDP/FF DPI, BDP/FF pMDI or placebo after methacholine challenge, according to a double-blind, double-dummy, cross-over design. Lung function and Borg dyspnoea score were assessed up to 30 min postdose. Results: FEV1 adjusted mean difference between BDP/FF DPI and BDP/FF pMDI at 5 min postdose was 2 ml (95% confidence interval: –0.060; 0.065). A similar result was observed at the other time points. Median time to 85% recovery in FEV1 was 8 min for BDP/FF DPI, 7.5 min for BDP/FF pMDI and 28 min for placebo (P = 0.554 DPI vs. pMDI). The Borg score improved after treatment with both BDP/FF DPI and pMDI and the effect was greater than after placebo. Median time to reach 50% recovery was 4.2 min for BDP/FF DPI, 4.0 min for BDP/FF pMDI and 10.0 min for placebo (P = 0.609 DPI vs. pMDI). Conclusions: Extrafine Foster® NEXThaler, a flow-independent DPI, is comparable to extrafine Foster® pMDI when administered as reliever therapy after methacholine challenge, thus supporting the maintenance and reliever therapy approach also with Foster® NEXThaler.