Objective: This study investigates the preventive and therapeutic effects of medical radiation protection spray (Bergmann) compared to triethanolamine cream in patients undergoing radiotherapy following breast cancer surgery. Methods: Ninety patients with breast cancer who received postoperative radiotherapy between July 2018 and July 2021 were randomly divided into the Bergmann treatment (experimental) group and the triethanolamine cream treatment (control) group, with 45 patients in each group. Radiodermatitis severity was assessed using the RTOG radiodermatitis grading standards. Results: The radiation dose required to develop grade I radiodermatitis was significantly higher in the experimental group compared to the control group, at (36.13 ± 1.17 Gy) and (25.38 ± 0.63 Gy), respectively. At a radiation dose of 30 Gy, the proportion of grade I radiodermatitis cases in the experimental group was significantly lower than in the control group (P = 0.002). At radiation doses of 40 Gy and 50 Gy, the proportion of grade II radiodermatitis cases in the experimental group was also significantly lower than in the control group (P < 0.001). No cases of grade III or higher radiodermatitis were observed in the experimental group, while three cases of grade III radiodermatitis occurred in the control group, although the difference was not statistically significant. No patients in the experimental group discontinued treatment due to radiodermatitis or mucosal reactions, whereas two patients in the control group interrupted treatment due to these reactions but eventually completed therapy. Conclusion: Bergmann spray effectively prevents radiodermatitis in patients undergoing radiotherapy after breast cancer surgery and is more effective than triethanolamine cream in treating skin lesions. Its ease of use improves the quality of life for patients undergoing radiotherapy and ensures successful treatment completion. Bergmann is suitable for clinical promotion and application.