Supplement analysis backed by scientific evidence · PT

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Limited evidenceStress & mood

Xiao Yao San

A classical Chinese formula prescribed for stress-related complaints. Meta-analyses report benefit in functional gut disorders and some mood outcomes, but nearly all trials are small, Chinese and at high risk of bias.

Evidence last reviewed: August 2026

What the science says

  • Benefit in functional gastrointestinal disorders Limited evidence

    A meta-analysis with trial sequential analysis of randomized trials found Xiao Yao San improved symptoms in functional gastrointestinal disorders compared with conventional treatment. The authors flagged low study quality and possible publication bias as limits on confidence.

  • Insomnia with anxiety Limited evidence

    A pooled analysis of randomized trials reported improvement in insomnia accompanied by anxiety, mostly compared against or added to standard drugs. Blinding was rare and follow-up short.

  • Blood pressure effects are uncertain Limited evidence

    A systematic review and meta-analysis in hypertension found reductions in blood pressure when the formula was added to antihypertensive drugs, but the evidence was rated low quality. It should not replace antihypertensive treatment.

Dosage & safety

Studied doseTrials typically used standard decoction or granule preparations two to three times daily for 4–8 weeks. Commercial granules generally follow the classical eight-herb ratio; follow the product label.
SafetyContains licorice, which in prolonged use can raise blood pressure and lower potassium. Herb quality and composition vary between manufacturers, and interactions with sedatives, anticoagulants and antihypertensives are plausible. Avoid in pregnancy and do not use in place of treatment for diagnosed depression or anxiety.

Scientific references

Where to buy

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