Topical Chinese herbal medicine in treating atopic dermatitis (eczema): A systematic review and meta-analysis with core herbs exploration

Topical Chinese herbal medicine (CHM) is commonly used to relieve atopic dermatitis (AD); however, the up-to-date evidence concerning the effectiveness of topical CHM on treating AD is lacking. Moreover, the CHM prescriptions are often too complicated to realize the overall mechanisms of CHM, especially when compared to western medicines (WM). To evaluate the effectiveness of topical CHM for treating AD by conducting a meta-analysis on randomized clinical trials (RCTs). Twenty RCTs comparing topical CHM to active control/placebo were included in the final analysis. The primary outcome was the symptom scores changed from baseline and the effectiveness rate was the secondary outcome. Subgroup analysis on different initial symptom severity and the different interventions in control groups was performed. System pharmacology analysis was performed to explore core CHM and possible pharmacological mechanisms of CHM for AD. Compared with active/blank placebo, topical CHM seemed more effective (SMD: −0.35, 95 %CI: −0.59 to −0.10, p-value = 0.005, I2 = 60%). The effectiveness rate was higher (RR: 1.29, 95 %CI 1.15–1.44, p-value <0.00001, I2 = 71%). In subgroup analysis, mild and moderate AD patients with topical CHM were more effective than placebo (SMD: −0.28, 95 %CI -0.56 to −0.01, p-value = 0.04, I2 = 5%; −0.34, 95%CI -0.64 to −0.03, p-value = 0.03, I2 = 0%, separately). Topical CHM has 1.25 times more effective than the topical glucocorticoid (95 %CI 1.09–1.43, p-value = 0.001, I2 = 64%). Core CHMs, such as Phellodendron chinense C.K. Schneid., Sophora flavescens Ait., Cnidium monnieri (L.) Cusson, and Dictamnus dasycarpus Turcz., had effects on the pathways on immune and metabolism systems different from WM. Our results exploit the potential role of CHM on treating AD, especially for mild and moderate AD.