Objective To explore the clinical effect of Huatan Huoxue Xiaocuo decoction combined with minocycline and red and blue light in the treatment of cystic acne and its impact on the GAGS score. Methods A total of 80 patients with cystic acne admitted to the Skin Beauty Center of Hospital 407 Tianshui from January 2023 to January 2024 were selected as the research subjects, and they were divided into control group and observation group according to the random number table method, with 40 patients in each group. The control group was treated with minocycline combined with red and blue light, and the observation group was treated with Huatan Huoxue Xiaocuo decoction on the basis of the control group. The clinical efficacy, TCM symptom scores, GAGS score and inflammatory factor levels were compared between the two groups. Results The total effective rate of treatment in the observation group was 95.00%, which was higher than 75.00% in the control group, and the difference was statistically significant (P <0.05). The symptom scores of pustular skin lesions, anorexia, dull tongue and deep hesitant pulse in the observation group were lower than those in the control group, and the difference were statistically significant (P <0.05). The GAGS score of the observation group after treatment was lower than that of the control group, and the difference was statistically significant (P <0.05). The levels of INF-γ, IL-6 and IL-8 in the observation group after treatment were lower than those in the control group, and the difference were statistically significant (P <0.05). Conclusion The treatment of cystic acne patients with Huatan Huoxue Xiaocuo decoction combined with minocycline and red and blue light can improve clinical efficacy, reduce GAGS score, promote the elimination of inflammatory factors, and improve clinical symptoms, which is worthy of application.