Chinese Herbal Liniments, Plasters, Baths and Foot Soaks

What "external use" means

In Chinese medicine, "external use" (sometimes "external application") covers herbal products used on the outside of the body: liniments and medicated oils, plasters and patches, ointments, herbal baths and washes, and foot soaks. They are very common in homes and herb shops. This page describes them and what is known about benefit and risk. It gives no recipes and no instructions, because home-made mixtures and amounts are where problems arise. For specific products see Tiger Balm, White Flower Oil, Zheng Gu Shui and other topical Chinese products.

Traditional view versus tested evidence

Traditionally, external products are described as moving qi and blood, warming or cooling, or "dispelling dampness". Those are traditional frameworks (see Qi, yin and yang as traditional concepts), not measured findings. What research has measured is narrower: pain scores, blood pressure, wound healing, and adverse events in specific products.

What the research shows

1. Herbal foot bath added to usual hypertension treatment

   Promising but limited; quality low

   A meta-analysis of randomized trials found lower systolic (mean difference 6.69) and diastolic (5.83) blood pressure and few adverse effects, but trials had inadequate randomization and blinding and no independent testing of herb purity or potency. [1]

2. External TCM for bone cancer pain

   Insufficient to promising; quality poor

   Six trials (534 patients) in China favored external applications for pain relief compared with morphine, radiotherapy or bisphosphonates; reporting was poor, no severe adverse events were found, and the authors called the evidence weak. [2]

3. Chinese herbal medicines for diabetic foot ulcers (any route, added to standard care)

   Weak

   49 trials, all in China (3,646 people), mostly unclear or high risk of bias; weak evidence of more ulcers healing; the authors said safety conclusions could not be firm. [3]

4. Allergy, contact dermatitis or burns from herbal plasters and washes

   Proper evidence not found

   We searched PubMed for reviews of skin reactions to topical Chinese herbal products and found no usable review.

Trials of foot soaks and plasters cannot be blinded well, because people can feel and smell them, so expectation effects are likely. Most trials were done in China, where the Chinese-language trial literature has known quality problems; see quality of TCM clinical trials.

Plasters and patches

Herbal plasters stay in contact with skin for hours, which raises the chance of irritation. We did not find a review of how often reactions occur. The ingredient list may be incomplete: undeclared substances have been found in Chinese herbal products generally. [7] See reading a Chinese patent medicine label.

Herbal baths and foot soaks

A bath or soak combines two things: the herbs and the heat of the water. Burns, fainting and dehydration risks from hot water are covered in hydrotherapy safety. People with diabetes or reduced feeling in the feet need particular care: the US National Institute of Diabetes and Digestive and Kidney Diseases says people with diabetes should not soak their feet because skin will become too dry, and that with diabetes nerve damage you may burn your feet and not know it. [8] Ask your diabetes care team before any soak. We give no temperatures or times, because safe limits depend on the person.

Foot reflexology, sometimes combined with soaks, is covered separately: reflexology.