Patients with severe asthma are refractory to inhaled corticosteroids and the majority are characterized by eosinophilic airway inflammation (sputum or bronchoalveolar lavage [BAL]), with elevated exhaled nitric oxide (FeNO), and Type 2 gene signatures (IL‐4, ‐5 and ‐13). Here, IL4 is linked to asthma.