〔Abstract〕 Objective To explore the effects of compound dextromethorphan hydrobromide syrup on symptom relief time and medical expenses of children with persistent cough after infection. Methods A total of 88 children with persistent cough after infection treated in the Aviation General Hospital from December 2022 to December 2023 were selected as the study objects and divided into a control group and an observation group by random number table method, with 44 cases in each group. The control group was treated with compound methoxyphenamine capsule, the observation group was treated with compound dextromethorphan hydrobromide syrup on the basis of the control group. The duration of symptom relief, medical expenses, levels of inflammatory factors and health status of the two groups were compared. Results The remission time of cough, sputum, pharyngeal itch and asthma in the observation group was shorter than those in the control group, and the differences were statistically significant (P < 0.05). There was no significant difference in medical expenses between the two groups (P > 0.05). After 2 weeks of treatment, the levels of serum interleukin (IL) -4 and tumor necrosis factor-α (TNF-α) in the observation group were lower than those in the control group, with statistical significance (P < 0.05). After 2 weeks of treatment, the physiological, psychological and social scores of Leicester cough questionnaire (LCQ) in the observation group were higher than those in the control group, and the differences were statistically significant (P < 0.05). Conclusion Compound dextromethorphan hydrobromide syrup can effectively promote the relief of symptoms in children with persistent cough after infection, reduce their inflammatory response and improve their health.