The Health Benefits of Xiao Yao San

Xiao Yao San is a blend of herbs used for centuries in Traditional Chinese Medicine (TCM). Practitioners of TCM believe Xiao Yao San works by clearing liver stagnation to improve the flow of qi (energy). Stagnant liver qi is said to affect the blood and contribute to stress/mood swings, pain, irritability, constipation, abdominal pain, premenstrual syndrome (PMS), and irregular menstrual periods.

Xiao Yao San can be hand-blended using the herbs themselves, but it is also sold as a dietary supplement. Although blends can vary, the herbs most often combined in Xiao Yao San are:

• Bupleurum (chai hu)
• Dong quai (dang gui)
• White peony root (bai shao)
• White atractylodes (bai zhu)
• Poria (fu ling)
• Peppermint (bo he)
• Quick fried ginger root (pao jian)
• Licorice root (zhi gan cao)

A variation called Jia Wei Xiao Yao San (augmented rambling powder) contains all eight herbs with the addition of peony bark (mu dan pi) and gardenia fruit (zhi zi).

Health Benefits

Although there's limited scientific research looking at the effectiveness of Xiao Yao San for therapeutic reasons, and most of what does exist are animal studies, there are a handful of diseases and conditions for which the herbal blend shows some promise.

Depression

One animal study published in Phytotherapy Research suggests that Xiao Yao San may help relieve depression by improving amino acid metabolism and altering gut microflora.

A review published in Evidence-Based Complementary and Alternative Medicine included 26 randomized control trials involving 1,837 people with depression. The studies compared Xiao Yao San to a placebo and different antidepressants, and examined it as an adjunct to antidepressants as well.

The review concluded that Xiao Yao San appeared to improve the effectiveness of antidepressants. However, there was no noticeable improvement in depression with Xiao Yao San alone.

Despited these findings, the study authors stated the research was poorly designed and more rigorous trials would be necessary before Xiao Yao San can be recommended to treat depression.

Post-Traumatic Stress Disorder (PTSD)

In 2009, researchers discovered Xiao Yao San lessened anxiety behaviors in stress-induced rats. A later study linked this effect to the neurosteroid allopregnanolone, a natural hormone derived from progesterone identified as a key player in the development of PTSD.

Again, using stress-induced rats, researchers found Xiao Yao San not only lowered anxiety behaviors, but also increased brain levels of allopregnanolone. 

Anti-inflammatory compounds in Xiao Yao San, paeoniflorin and isoliquiritin, may be key to its beneficial impact on PTSD, according to a 2017 study. Researchers found that these compounds, previously shown to relieve depression, impact neurobiological pathways associated with PTSD symptoms.

In addition, a 2017 study found the blend counteracts oxidative stress using similar pathways as the antidepressant Prozac (fluoxetine), a common PTSD treatment. 

Stress

Research investigating Xiao Yao San's effect on stress is limited to rodent studies. The stress hormone cortisol impacts neurons in the hippocampus, the part of the brain responsible for concentration, memory, and mood. One study on rats found Xiao Yao San appears to protect against this.

Indigestion

Xiao Yao San is traditionally used to soothe a "sour" stomach. Current research suggests the herbal blend helps relieve functional dyspepsia, better known as chronic indigestion.

According to a review of 14 studies published in the Journal of Gastroenterology and Hepatology, Xiao Yao San may help relieve stomach discomfort, nausea, bloating, and belching associated with indigestion.

Investigators noted that the herbal preparation appears to work as well as prokinetic drugs—medications that increase intestinal motility, such as Motilium (domperidone) and Reglan (metoclopramide).

A 2018 review of Chinese herbal medicine remedies for indigestion also confirmed these results and suggested Xiao Yao San was more effective than prokinetic medications.

Possible Side Effects

Xiao Yao San is generally regarded as safe and non-toxic. Reported side effects from individual herbs in the blend include: 

• Cramps (licorice root) 
• Dizziness (licorice root)
• Edema (licorice root)
• Headache (licorice root)
• High blood pressure (licorice root)
• Low blood sugar (poria)
• Lactation in non-lactating women (licorice root)
• Numbness (licorice root)
• Stomach discomfort (dong quai)
• Weakness (licorice root)

Contraindications

Each herb in the blend is considered safe, though some contraindications apply for individual ingredients at certain doses. If you have any of the following conditions, talk to your healthcare provider before taking Xiao Yao San: 

• Pregnancy: Dong quai can stimulate uterine contractions and should not be taken during pregnancy except under the guidance of a healthcare provider or midwife trained in TCM.
• Cardiovascular disease: Two ingredients in Xiao Yao San are not recommended for people with cardiovascular disease—licorice root, which raises blood pressure, and poria, which has a diuretic effect.
• Kidney disease: Similarly, licorice root and poria are not recommended for people with kidney disease.
• Diabetes: Poria should not be taken at the same time as blood-sugar-lowering medications such as insulin as it can cause low blood sugar.

In addition, licorice root is not recommended for people over 65. Long-term use of the herb can cause high blood pressure and lower potassium levels, potentially leading to heart and muscle problems.

Selection, Preparation, & Storage

As Free and Easy Wanderer, Relaxed Wanderer, Xiao Yao San, and Xiao Yao Wan, the herbal blend is available as capsules, tinctures, and teapills (herbal extracts compressed into small, pea-sized balls). They can be found at natural-food stores, stores specializing in herbal remedies, and online. Teapills are a convenient form of dosing but perhaps not the ideal form according to many TCM practitioners, who tend to prefer herbal decoctions.

Dietary supplements are largely unregulated, and the content of any product may differ from what is specified on the product label or contain doses different from the specified amount for each herb. Many brands of Xiao Yao San list only a proprietary blend or list ingredients in Chinese.

A Word From Verywell

Currently, there is not enough research to support the use of Xiao Yao San as a treatment for any medical condition. If you're considering taking Xiao Yao San, consult your healthcare provider. Although primary care physicians increasingly are becoming familiar with herbal medicine, it may be advised to consult a licensed TCM practitioner.