Xiaoyao-san May Improve Irritable Bowel Syndrome Symptoms, QOL

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Using a systematic review and meta-analysis, researchers examined the efficacy and safety of xiaoyao-san for treating irritable bowel syndrome.

Xiaoyao-san, a traditional Chinese medicine formula, may help patients manage irritable bowel syndrome (IBS), according to a study published in the European Journal of Integrative Medicine.

Researchers conducted a systematic review and meta-analysis to assess the efficacy and safety of xiaoyao-san for treating IBS. Using 9 electronic databases, researchers searched for relevant randomized controlled trials (RCTs) of xiaoyao-san for IBS until April 30, 2021.

Eligible studies used xiaoyao-san or modified xiaoyao-san (herbs-added or deleted prescription) as an experimental intervention. Studies that used conventional treatments and placebo or no treatments were also eligible. Only patients diagnosed with IBS based on Rome criteria I to IV were included in the study.

The primary outcome was efficacy rate. Secondary outcomes included IBS symptom scores on abdominal pain, abdominal distension, and diarrhea or constipation; the Irritable Bowel Syndrome Symptom Severity Scale (IBS-SSS); Irritable Bowel Syndrome Quality of Life (IBS-QOL); a Short Form Health Survey (SF-36); and adverse events.

Of 420 studies identified, 21 studies met full inclusion criteria and were included in the meta-analysis. The studies included 1858 patients with IBS, and the sex ratio was nearly 1:1 (men, 742; women, 830), excluding 4 studies that did not report sex distribution.

The overall efficacy of xiaoyao-san demonstrated significant improvement (risk ratio [RR], 1.26; 95% CI, 1.21-1.33; P <.00001; I2=2%).

The abdominal pain score from baseline to the endpoint was assessed in 8 studies with 807 patients. The overall abdominal pain score of xiaoyao-san indicated significant improvement (mean difference [MD], – –0.36; 95% CI, -0.53 to -0.19; P <.0001; I2=86%).

The abdominal distention score was evaluated from baseline to the endpoint in 5 studies with 408 patients. The overall abdominal distention score of xiaoyao-san demonstrated significant improvement (MD, -0.38; 95% CI, -0.47 to -0.30; P <.00001; I2=25%).

A total of 7 studies with 617 patients assessed the diarrhea score from baseline to the endpoint. The overall diarrhea score of xiaoyao-san was associated with significant improvement (standardized mean difference, -0.78; 95% CI, -1.29 to -0.28; P <.002; I2=88%).

One study with 124 patients evaluated the constipation score from baseline to the endpoint. Pooled results indicated no significant difference (MD, -0.16; 95% CI, -0.36-0.04; P =.11).

A single study with 131 patients comparing xiaoyao-san plus Chinese herbal medicine (CHM) with CHM evaluated the IBS-SSS from baseline to the endpoint. The pooled results showed a significant difference (MD, -12.22; 95% CI, -16.23 to -8.21; P <.00001).

In addition, 3 studies with 254 patients assessed the IBS-QOL from baseline to the endpoint. Pooled results showed a significant difference in 5 of 8 subscales, including dysphoria, interference with activity, body image, food avoidance, and social reaction, all of which were I2=0%. A single trial reported the total score of IBS-QOL, with the pooled result demonstrating a significant difference (MD, 22.51; 95% CI, 17.15-27.87; P <.00001).

Of the 21 included trials, 5 reported an evaluation of the adverse events of xiaoyao-san, but none identified any events in the experimental and control groups.

Among several limitations, all studies were conducted in China, and the composition and formulation of xiaoyao-san varied in each trial. In addition, some indices had an insufficient number of trials to identify the statistical effects of xiaoyao-san, and many of the studies had a small sample size with low methodologic quality.

“The present meta-analysis indicates that [xiaoyao-san] may be effective and safe in managing IBS as a single or combination therapy, particularly abdominal pain, abdominal distention, and diarrhea,” the researchers wrote. “Furthermore, [xiaoyao-san] can improve abdominal pain, IBS-SSS, and the patients’ quality of life… Interpretation and generalization of these results for their clinical use should be conducted with great caution.”


Lee JH, Sung W-S, Bak SB, Kim EJ, Kim YW. Evaluation of Xiaoyao-san for treatment of irritable bowel syndrome: a systematic review and meta-analysis of randomized controlled trials. Eur J Integr Med. Published online June 25, 2022. doi:10.1016/j.eujim.2022.102152