Our data showed that airways and tissue eosinophilia, as well as the expression of total IgE, OVA‐specific IgE, IL‐13 and IL‐33 in response to OVA challenge, were inhibited by serial CSE exposure, which may be associated with difficult‐to‐treat asthma with smoking. This evidence concerns the gene IGHE and Increased total eosinophil count.