What Is Xiao Yao San?

Xiao Yao San is a blend of herbs used for centuries in traditional Chinese medicine (TCM). Xiao Yao San is said to clear "liver stagnation" by improving the flow of qi (energy). Stagnant liver qi is said to contribute to stress, mood swings, pain, irritability, constipation, abdominal upset, premenstrual syndrome (PMS), and irregular periods.

The dried ingredients of Xiao Yao San can be hand-blended or purchased as a dietary supplement. The herbs and plants most often used in Xiao Yao San are:

• Bupleurum
• Dong quai
• White peony root
• White atractylodes
• Poria mushroom
• Peppermint
• Quick-fried ginger root
• Licorice root

A variation called Jia Wei Xiao Yao San contains all eight herbs with the addition of peony bark and gardenia fruit.

This article explores how Xiao Yao San is used in traditional Chinese medicine, including the scientific evidence to support its use. It also explains how to use Xiao Yao San safely as well as the possible risks and side effects of this ancient Chinese remedy.

What Is Xiao Yao San Used For?

Although there are few studies strongly supporting the use of Xiao Yao San (most of which are animal- or lab-based), there are a handful of conditions for which the herbal remedy has shown promise.

Depression

An animal study published in Phytotherapy Research suggests that Xiao Yao San may help relieve depression by reducing neuroinflammation (inflammation of the brain and spinal cord).

It is a controversial theory in which imbalances in the gut microflora, bacteria and other microorganisms in the digestive tract, are thought to contribute to neuroinflammation and, in turn, depression. Xiao Yao San is said to help by creating compounds that help normalize the imbalance.

A review of studies published in Evidence-Based Complementary and Alternative Medicine evaluated 26 high-quality trials involving 1,837 people with depression. The researchers concluded that Xiao Yao San appeared to improve depression when taken with an antidepressant. It had no direct effect on depression on its own, however.

Post-Traumatic Stress Disorder (PTSD)

In 2009, researchers discovered Xiao Yao San reduced anxiety behaviors in stress-induced rats. 

A later study, also involving rats, linked the effect to a natural hormone called allopregnanolone that is thought to play role in post-traumatic stress syndrome (PTSD). It was found that a daily dose of Xiao Yao San not only lowered anxiety behaviors but also increased levels of allopregnanolone in the brain. 

Anti-inflammatory compounds found in Xiao Yao San, called paeoniflorin and isoliquiritin, may also lessen PTSD symptoms, according to a 2017 review in Frontiers of Pharmacology. Researchers found that both compounds appeared to alter pathways in the brain associated with PTSD.

A lab-based study published in Scientific Reports suggests that Xiao Yao San counteracts oxidative stress in the brain in a similar way as the antidepressant drug Prozac (fluoxetine) commonly used to treat PTSD. Oxidative stress is damage caused to cells by unstable atoms known as free radicals. In the brain, this can lead to neuroinflammation and an increased risk of depression. 

Indigestion

Xiao Yao San is traditionally used to soothe a "sour stomach," also referred to as functional dyspepsia or chronic indigestion.

According to a review of studies published in the Journal of Gastroenterology and Hepatology, Xiao Yao San is able to relieve indigestion symptoms (stomach upset, nausea, bloating, belching) better than acid reflux medications like Motilium (domperidone) and Reglan (metoclopramide).

A 2018 review in Therapeutic Advances in Gastroenterology confirmed the results and suggested Xiao Yao San was more effective in relieving indigestion than either of these drugs.

Despite the positive findings, there was a lack of high-quality studies in these reviews.

Possible Side Effects

Xiao Yao San is generally regarded as safe. Some 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

Certain components of Xiao Yao San may not be safe for use in some people. If you have any of the following conditions, talk to your healthcare provider before using 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 (meaning it rids the body of salt and water).
• Kidney disease: Licorice root and poria are also not recommended for people with kidney disease.
• Diabetes: Poria should not be taken at the same time as anti-diabetes medications like insulin as it can cause a steep drop in 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, leading to heart and muscle problems.

Always check with your healthcare practitioner before starting any herb. Mention all drugs and supplements you take, as well as any conditions you have.

Dosage and Preparation

Xiao Yao San is available as capsules, tinctures, and teapills (herbal extracts compressed into pea-sized balls). It can be found online, at many natural food stores, and in specialty herbalist shops.

Xiao Yao San supplements are sold under different brand names, including Free and Easy Wanderer, Relaxed Wanderer, or Rambling Powder. Xiao Yao Wan is the teapill formulation.

Capsules and teapills are the most convenient forms of Xiao Yao San, but TCM practitioners tend to prefer traditional hand-blended herbs for making decoctions. Decoctions are made by steeping and mashing the mixed ingredients in boiling water to create a therapeutic tonic.

There is no recommended dose of Xiao Yao San in any form. Follow instructions on product labels or provided by your healthcare provider.

What to Look For

Dietary supplements are largely unregulated in the United States. Those imported from China pose extra risks as the ingredients are often written in Chinese and have been known to contain heavy metals, drugs, and other contaminants, according to the National Center for Complementary and Integrative Health.

When choosing a supplement, look for products that have been certified by third-party authorities like ConsumerLab, U.S. Pharmacopeia (USP), or NSF International. These certifying bodies ensure that supplements are pure and only contain the ingredients listed on the product label.

Summary

Xiao Yao San is a mixture of herbs and dried plants—including licorice, dong quai, and poria mushrooms—used in traditional Chinese medicine. It is used to treat a wide range of health conditions, including depression, anxiety, indigestion, constipation, pain, and menstrual problems.

Despite centuries of use, the evidence supporting Xiao Yao San remains relatively weak.

Side effects include nausea, cramps, dizziness, headache, and stomach upset. Certain people should not use it, so consult with your healthcare provider before trying Xiao Yao San.

A Word From Verywell

Although primary care physicians are increasingly familiar with herbal medicines, it may be beneficial to consult a licensed TCM practitioner.