In the search for an objective measure or biomarker of asthma control, fractional exhaled nitric oxide (FeNO) has looked a promising candidate. However, the benefit of using FeNO in addition to symptom-guided treatment is not clear. Turner S et al (Lancet Respiratory Medicine 2022;10:584–92 https://doi.org/10.1016/S2213-2600(21)00486-0) have successfully conducted and adequately powered study to evaluate the efficacy of adding FeNO to symptom-guided treatment in children with asthma vs only symptom-guided treatment. This is the first randomised clinical trial (RCT) to examine whether the addition of FeNO to symptom-guided treatment reduces asthma exacerbations in children. The RAACENO study was a multicentre, …