Objective To observe the clinical efficacy and safety of external application of Piyan Formula in treating epidermal growth factor receptor tyrosine kinase inhibitor(EGFR-TKIs)-related rashes.Methods Sixty cases of EGFR-TKIs-related rash patients were randomly allocated into either a treatment group or a control group.The treatment group received external application of Piyan Formula to the rash area twice daily for 14 days.The control group received external application of fucidic acid cream to the rash area twice daily for 14 days.Changes in rash grading,itching grading,quality of life scores and adverse event were observed and recorded in both groups.At the same time,levels of hypersensitive C-reactive protein,interleukin(IL)-6,and IL-1β were measured before treatment and 24 hours after treatment.Results After treatment,the rash severity,itching severity,and quality of life scores were notably lower in the treatment group compared to the control group(P<0.05).The levels of hypersensitive C-reactive protein,IL-6,and IL-1β exhibited a significant decrease compared to their pre-treatment values.(P<0.05).Compared with the control group,the levels of hypersensitive C-reactive protein,IL-6,and IL-1β decreased in the treatment group,with statistically significant differences(P<0.05).No adverse events related to Piyan Formula or fucidic acid cream occurred during the treatment process.Conclusion External application of Piyan Formula in treating EGFR-TKIs-related rashes shows significant clinical efficacy,can effectively reduce the levels of inflammatory factors,and has high safety,thus warranting clinical promotion.