Objective To explore the effect of self-made Xiaodao decoction combined with isotretinoin erythromycin gel on skin lesion symptoms in patients with mild to moderate acne vulgaris. Methods A total of 48 patients with mild to moderate acne vulgaris who visited Luzhou TCM Hospital from August 2024 to November 2025 were selected as the research subjects, and they were divided into the control group and the observation group by the random number table method, with 24 patients in each group. The control group was treated with isotretinoin erythromycin gel, and the observation group was treated with self-made Xiaodao decoction on the basis of the control group. The skin lesion symptoms, sebum excretion rate (SER), serum inffammatory factor indicators, clinical efffcacy and adverse reaction rate were compared between the two groups. Results The skin lesion symptom score of the observation group at 2 months after treatment was lower than that of the control group (P<0.05). The SER of the observation group at 2 months after treatment was lower than that of the control group (P<0.05). The serum inffammatory factor indicators of the observation group after treatment were all lower than those of the control group (P<0.05). The total effective rate of the observation group (95.83%) was higher than that of the control group (66.67%) (P<0.05). The incidence of adverse reactions in the observation group (8.33%) was lower than that in the control group (37.50%) (P<0.05). Conclusion For patients with mild to moderate acne vulgaris, the treatment scheme of isotretinoin erythromycin gel combined with self-made Xiaodao decoction cannot only improve clinical efffcacy and treatment safety, but also more effectively promote the regression of skin lesion symptoms, inhibit excessive sebum secretion, and reduce local inffammatory response.