Herein, we analyzed 19 patients with refractory anti‐MDA5 antibody‐positive CADM with rapidly progressive interstitial pneumonitis treated with tacrolimus trough concentration‐escalating dual therapy (glucocorticoids combined with tacrolimus) because of a lack of disease control with intensive combination immunosuppressive therapy (glucocorticoids combined with immunosuppressive agents). The gene discussed is IFIH1; the disease is Interstitial pneumonitis.