Herbal compresses have been used for thousands of years. Researchers in Thailand are exploring the science behind them

The scent of fragrant lemongrass mingles with earthy ginger and tangy tamarind, punctuated by the sharp, menthol-like aroma of camphor. It’s a familiar smell for spa-goers: a traditional Thai herbal compress.

The treatment combines herbs in a cotton cloth, which is wrapped into a compact ball and steamed for around 10 minutes before the practitioner applies it to the body, typically after a massage.

Herbal compresses have been used for centuries for muscle aches, joint pain, and to reduce inflammation. However, it’s unclear how much benefit comes from the herbs: a 2015 review paper highlighted that the effects were mainly associated with heat, which increases blood flow and reduces pain.

While herbal medicine is a multi-billion industry that’s prevalent across the world, varying cultural practices, beliefs and knowledge have made it difficult to standardize or regulate. According to a report from the World Health Organization (WHO) in 2018, nearly half of member states did not have a national policy on traditional medicine, and only 64% had regulations on herbal medicines.

WHO says lack of research data is one of the biggest barriers to effective regulation.

In Thailand, the Center of Excellence in Applied Thai Traditional Medicine Research (CEATMR) at Thammasat University in Pathum Thani aims to provide research on the unique properties of the herbs used in herbal compresses and make this ancient remedy more accessible, says Arunporn Itharat, the center’s director.

Like other countries in Southeast Asia, alternative therapies are popular in Thailand, with surveys finding herbal medicine usage common among the population, particularly in rural areas. However, there’s a lot of traditional knowledge that needs to be scientifically proven, says Itharat.

“Herbs vary significantly in their properties, and this variability is one of the main challenges we face,” she says. “We need to validate the (extraction) process to ensure consistency across every batch.”

Another problem is that “a single herb can have many different varieties,” says Itharat, adding that “misidentification is a big issue in herbal medicine.”

In 2020, her research, published in the peer-reviewed Science & Technology Asia, found that some herbs can contribute to the efficacy of a herbal compress. “By isolating and testing each ingredient, the study identifies specific components contributing to the overall anti-inflammatory effect,” says Itharat.

The research center is applying traditional knowledge, such as the timing of harvesting the herbs, to make the extracts more effective.

For example, with zingiber montanum, a type of ginger known as “plai” in Thailand, “Elders have always emphasized that roots must be collected in the winter, when the plant has withered and its active compounds have concentrated in the roots,” says Itharat. This kind of traditional knowledge is often anecdotal and hasn’t been scientifically tested — so CEATMR is working to validate and standardize it.

“We can develop the extract into a finished medicine, making it more convenient to use, and we can control the quality,” says Itharat.

Modern applications

These extracts have been incorporated into modern products like emulsion-gels and creams, which are sold in CEATMR’s herbal pharmacy in Thammasat University.

Itharat is also exploring other innovative application methods in her research, such as a cooling hydrogel patch, which research indicates offers a more controlled release of the herbal extract compared to oils and creams, and an electric herbal compress, in collaboration with Thailand’s National Science and Technology Development Agency and National Electronics and Computer Technology Center.

A ball-shaped heat-conducting compress is attached to a long handle with a battery inside. Instead of having herbs wrapped in the compress, a gel containing concentrated herbal extracts is applied to the skin and massaged by the electric compress.

“Normally, compresses need to be steamed and replaced repeatedly, but our electric compress can stay on for up to eight hours,” says Itharat.

Applying the herbal gel directly to the skin offers greater efficacy than through a cotton cloth, as well as a standardized, controlled dosage of the active ingredient, says Itharat. The electric compress is still under development, as the team tries to reduce the size of the handle on its prototype to make it smaller and easier to carry.

A growing industry

Thailand is one of a handful of countries that has invested heavily in traditional medicine research and legislation. In 2021, Thammasat University began offering the Master of Thai Traditional Medicine Clinic Program, the nation’s first curriculum of its kind that integrates traditional and modern medicine.

Scientific interest in traditional therapies and the effects of herbal medicine in growing elsewhere, too: A 2020 literature review noted a sharp increase in publications on medicinal plants globally since 2001, with around 5,000 publications per year over the past decade.

China and India, each with their own distinctive traditional medicine systems, have led research in the field, including work to standardize herbal knowledge. For example, researchers in China and Taiwan have built several databases for Traditional Chinese Medicine (TCM), collating information on thousands of herbs and their associated diseases, drug-likeness and interactions.

However, there’s still a huge gap in the available information: More than 50,000 plant species are used for medicinal purposes across the globe, and there’s limited cross-over between databases for different countries. Plant names are also often not standardized, which can lead to ambiguity about which herb is being discussed, risking ineffective treatment, or even poisoning.

Itharat hopes to see more traditional knowledge validated and introduced as complementary therapies to help patients heal and recover more quickly.

“Humanity has relied on nature for medicines for thousands of years, so the connection between nature and human health is undeniable,” says Itharat. “The challenge is to make this traditional knowledge more accessible while preserving it for future generations and sharing it globally,” she adds.

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