Efficacy of Wendan Decoction combined with conventional medicine for depression: a systematic review and meta-analysis

Clinical Snapshot

Key Findings

• P Value: Not reported in abstract

• Effect Size: Primary pooled SMD = -4.84 (favouring Wendan Decoction plus conventional medicine); Sensitivity analysis SMD = -4.18

• Primary Outcome: Depression severity measured by validated depression scales (specific scales not detailed in abstract)

• Nnt Or Sensitivity: NNT not calculable from reported data. SMD values of this magnitude are clinically implausible (Cohen's d benchmarks: 0.2 small, 0.5 medium, 0.8 large effect); an SMD of -4.18 to -4.84 would represent an effect approximately 5–6 times larger than the threshold for a 'large' clinical effect, strongly suggesting methodological artefact rather than true treatment effect

• Confidence Interval: Primary: 95% CI -7.54 to -2.14; Sensitivity analysis: 95% CI -5.26 to -3.10

Clinical Application

Modified Wendan Decoction is a variable herbal formula requiring specialised traditional Chinese medicine practitioners for preparation and prescription. Standardisation of formulation, dosing, and quality control presents significant challenges outside of Chinese healthcare systems. Herb-drug interactions with conventional antidepressants (particularly SSRIs, SNRIs, and TCAs) have not been systematically evaluated in this review. Wendan Decoction is not registered with the Therapeutic Goods Administration (TGA) as a listed or registered medicine in Australia. Individual herbal components may be available through TGA-listed complementary medicine products, but the specific combination formula is not subject to Australian regulatory oversight for efficacy or safety. The RACGP does not currently endorse Wendan Decoction for depression management. PBS listing is not applicable. Australian clinicians should note that the evidence base is derived entirely from Chinese RCTs of uncertain methodological quality, with implausibly large effect sizes that likely reflect significant bias. Any consideration of this therapy in Australian patients should be approached with extreme caution, with priority given to TGA-approved and PBS-listed antidepressant therapies supported by robust international evidence. The evidence, as reported, applies only to Chinese patients with depression treated in Chinese clinical settings. Applicability to diverse Western populations, including those with different comorbidity profiles, genetic backgrounds, and concurrent medication regimens, cannot be assumed.

Abstract

ETHNOPHARMACOLOGICAL RELEVANCE: Wendan Decoction is well-known traditional Chinese medicine formula commonly used in China for the treatment of gastrointestinal disorders and mood disorders related to phlegm-dampness and spleen deficiency. In clinical practice, depending on different symptoms, additional herbs may be included, resulting in a modified formula known as modified Wendan Decoction. AIM OF THE STUDY: To evaluate the efficacy of modified Wendan Decoction plus conventional medicine in the treatment of depression. MATERIALS AND METHODS: We independently conducted a meta-analysis of studies on the efficacy of modified Wendan Decoction for depression from inception to February 28, 2025, using electronic databases, including PubMed, Embase, Cochrane, Web of Science, Wanfang, VIP and SinoMed. Data from randomized controlled trials were extracted to evaluate treatment outcomes based on depression scales. RESULTS: A total of 402 articles were identified through database searches, and 13 studies, encompassing 1117 patients, were included. The initial pooled analysis revealed a significant treatment effect of the experimental group, yielding a standardized mean difference (SMD) of -4.84 (95% CI: -7.54 to -2.14), with high heterogeneity (I2 = 99%). Sensitivity analysis, excluding studies with high risk of bias, demonstrated an SMD of -4.18 (95% CI: -5.26 to -3.10) with moderate heterogeneity (I2 = 83%). Notable regional differences were found, with the study in Southern region exhibiting greater efficacy (SMD = -4.81, 95% CI: -6.38 to -3.23) compared to the study in Northern region (SMD = -3.03, 95% CI: -3.73 to -2.32). CONCLUSIONS: Our meta-analysis supports the efficacy of combining modified Wendan Decoction with conventional medicine for treating depression. Exploratory subgroup results suggest slightly greater improvements in Southern China, though this finding requires cautious interpretation and confirmation in future high-quality trials. PROSPERO Registration ID: CRD420251015690.

References

1. 1.Chen, X., Fan, Z., Xu, Y., Xu, W., Li, L., & Tan, H. (2026). Efficacy of Wendan Decoction combined with conventional medicine for depression: a systematic review and meta-analysis. Journal of Ethnopharmacology. https://doi.org/10.1016/j.jep.2026.121638