Alternatively, switching to anti-IL-4/IL-13 could be considered in this subgroup of patients, but careful monitoring of BEC and clinical parameters are recommended to assess the risk of symptomatic hypereosinophilia and/or evolution toward eosinophilic granulomatosis with polyangiitis (EGPA, former known as Churg-Strauss Syndrome) (38, 39). Here, IL4 is linked to eosinophilic granulomatosis with polyangiitis.