Objective To investigate the effect of Anchusa italica Retz.extract on cough variant asthma(CVA)and its mechanism of action.Methods Forty-eight SD rats of each eight were randomly divided into blank group(equal amount of saline),model group(equal amount of saline),control group(250 mg·kg-1 prednisone acetate)and experimental-A1,-A5,-A7 groups(61.1 mg·kg-1 Anchusa italica Retz.extract A1,48.8 mg·kg-1 Anchusa italica Retz.extract A5,201.8 mg·kg-1 Anchusa italica Retz.extract A7),continuous gavage for 28 d;except for the blank group,the other groups were made with ovalbumin-complete Freund's adjuvant.The number of cough times of each rat was observed.The changes in the expression of Toll-like receptor 4(TLR4),myeloid differentiation factor(MyD88)and nuclear factor κB(NF-κB)proteins were observed in the lung tissue.Results The cough times in the blank group,model group,control group and experimental-A1,-A5,-A7 groups were 1.10±0.22,8.33±1.24,3.08±0.65,3.31±0.99,3.08±1.02 and 3.06±0.68;the relative expression levels of TLR4 protein were 0.61±0.01,0.84±0.04,0.66±0.02,0.64±0.04,0.64±0.03 and 0.69±0.02;the relative expression levels of MyD88 protein were 0.54±0.08,0.86±0.06,0.71±0.06,0.65±0.05,0.64±0.08 and 0.70±0.06;the relative expression levels of p-NF-κB protein were 0.48±0.11,0.94±0.06,0.80±0.08,0.68±0.04,0.68±0.06 and 0.78±0.09.Compared with the experimental-A1,-A5,-A7 groups,control group,normal group,the differences were statistically significant in the model group(all P＜0.05).Conclusion The extract of Anchusa Italica Retz.can inhibit the symptoms of CVA rats,and the mechanism may be related to the inhibition of TLR4/MyD88/NF-κB signaling pathway.