Mechanistic Insights into Multiherb Formulations for Antibiotic-Associated Diarrhea: A Systematic Review of Preclinical Studies on Microbiome–Host Interactions

Antibiotic-associated diarrhea (AAD) is primarily driven by disruption of the gut microbiota accompanied by intestinal mucosal injury. Although multiherb formulations are widely used in East Asian medicine, their collective ecological effects and integrated microbiome–host mechanisms have not been systematically synthesized. This systematic review included 17 preclinical studies that investigated multiherbal formulations in AAD models. Given the substantial heterogeneity in the formulation composition, experimental design, and analytical platforms, a descriptive synthesis was performed. The included formulations were categorized into four clusters based on their shared herbal composition: Qiwei Baizhu San (QWBZP), Lizhong Tang (LZT), Gegen Qinlian Tang (GQT), and other supportive multiherbal formulations. The cluster-based synthesis revealed distinct convergent therapeutic strategies. The QWBZP and LZT clusters primarily supported the restoration of host metabolic and digestive functions, whereas the GQT cluster exhibited potent pathogen control effects with the suppression of opportunistic taxa. Across all clusters, a convergent microbiome–host response emerged, characterized by enrichment of commensal bacteria (e.g., Lactobacillus), upregulation of tight junction proteins (e.g., ZO-1, occludin), and attenuation of pro-inflammatory mediators (e.g., TNF-α, myeloperoxidase). Multiherb formulations in AAD models not only act as microbial modulators but also function as host-directed modulators that stabilize the intestinal homeostatic niche. Botanical interventions may facilitate endogenous microbiome recovery by reinforcing mucosal integrity and reducing environmental resistance. This ecological framework provides a rationale for future translational studies evaluating integrated herbal–probiotic strategies and precise microbiome management for patients with AAD, while further clinical validation is warranted.