e20548 Background: To assess the therapeutic effect of compound pholcodine syrup and compound codeine phosphate oral solution on lung cancer cough. Methods: A total of 60 patients with diagnosed middle-advanced stage lung cancer accompanied with lung cancer cough from Jan, 2022 to May, 2022 were enrolled . According to the method of random number table, the patients were divided into two groups: observation group and control group. Observation group received compound pholcodine syrup treatment, while control group received compound codeine phosphate oral solution treatment. The dosage of the two drugs was 15 ml each time, 3 times a day, and the treatment course was 5 days. The antitussive effectiveness, cough severity and quality of life , were observed and compared between the two groups before and after the 3 days and 5 days treatment, respectively. Results: All 60 patients completed the treatment. Both two groups were effective in controlling lung cancer cough. After the 3 days treatment, the antitussive effective rates of the observation group and the control group were 83.3% (25/30) and 73.3% (22/30), respectively, with no statistical significance ( P= 0.347). After the 5 days treatment, the antitussive effective rates of observation group and control group were 90.0% (27/30) and 86.6% (26/30), respectively, with no statistical significance ( P= 0.687). There was no significant difference in the composition of patient cough severity between observation group[moderate and severe cough, 56.7% (17/30) ] and control group [moderate and severe cough, 67.7% (20/30) ]. After 3 days treatment, cough symptoms were relieved in both groups. Patients with mild cough accounted for 73.3% (22/30) in the observation group and 56.7% (17/30) in the control group, the difference was not statistically significant ( P= 0.331). What's more, after 5 dyas treatment, there was also no significant difference( P= 0.067)between observation group[mild cough, 86.7%(26/30)] and control group [mild cough, 66.7%(20/30)] . In the meantime, there were no significant differences in the physiological score, psychological score, social score and total score of the Leicester Cough Questionnaire in Mandarin-Chinese scale before the treatment, after 3 days and 5 days treatment between the two groups (all P > 0.05). Patients in the observation group had a lower incidence of xerostomia (0.0% vs 20.0 %, P= 0.024) and constipation (0.0% vs 20.0 %, P= 0.024) than control group. Conclusions: Compound pholcodine syrup and compound codeine phosphate oral solution are effective in treating lung cancer cough with similar antitussive effectiveness. Compound pholcodine syrup has a lower incidence of xerostomia and constipation than control group, which indicates that the security may be better. Clinical trial information: ChiCTR2300076684.