There may be no better way to unwind from travel or work, or ease a few aches and pains, than to visit one of the world's many beloved hot springs. They dot the planet, offering one of nature's supreme treats, and since science has affirmed their healing applications and entrepreneurs have surrounded some with healthful amenities, why not plan a visit to one this winter?
Balneotherapy, or bath therapy, refers to the use of warm or cold bathing to treat an illness or condition; often the bath may be taken in mineral waters or mineral-laden mud or peloids (mature clay). Additionally, such baths can be accompanied by the drinking of mineral water and the inhalation of rejuvenating gases.
Benefits from “hot potting,” a term for soaking in natural hot springs, can include improved vascular function from heat therapy (hot water immersion), increased diameter of the artery for reducing vascular dysfunction (based on a review of various studies), and potential use as thermal therapy for those with risk of developing metabolic disease.
Hot potting has been used for thousands of years for a variety of ailments. And although some studies do indicate a number of health benefits derived from soaking in hot springs, hot potting has yet to be proven to detoxify the body, prevent certain diseases, or cure health issues. Also, a note of caution: water temperatures of hot springs can range from warm to quite hot; thus one should be mindful of one’s tolerances for prolonged heat exposure. And as with any therapeutic practice, it is not a substitute for consulting a physician about health problems.
And although some studies do indicate a number of health benefits derived from soaking in hot springs, hot potting has yet to be proven to detoxify the body, prevent certain diseases, or cure health issues.
Some Popular Global Hot Springs
There is a myriad of hot springs around the world to enjoy for relaxation and potential health benefits.
Blue Lagoon (Iceland)
The Blue Lagoon is a geothermal hot spring in Iceland that was created in 1976 using the Svartsengi Power Station’s wastewater that had accumulated over time. This wastewater is brine with a salt concentration that is about two-thirds that of seawater, as it is originally extracted from a geothermal reservoir resulting from a mixture of sea water and groundwater. The water is also home to a diverse microbial ecosystem.
The lagoon contains microalgae that can reduce uneven facial skin pigmentation, and there is research suggesting that extracts from the silica mud and algae there have the “capacity to improve skin barrier function and to prevent premature skin aging.” For the curious, the Blue Lagoon also offers its own line of facial skincare products derived from the lagoon’s microalgae and silica.
The lagoon contains microalgae that can reduce uneven facial skin pigmentation, and there is research suggesting that extracts from the silica mud and algae there have the “capacity to improve skin barrier function and to prevent premature skin aging.”
Hierapolis-Pamukkale (Turkey)
Equally remarkable are the remnants of Hierapolis, an ancient, Hellenistic spa town, spanning 1,077 ha (2,661 acres) in Pamukkale, Turkey. This geographical and architectural wonder, a UNESCO world heritage site since 1988, is known for its travertine (terrestrial limestone) terraces with pools and related hot springs that appeared naturally through the evolvement of regional tectonics.
The Pamukkale Geothermal Field is home to thermal and cold waters of varying categories. Its thermal waters are divided into calcium-bicarbonate and calcium-sulfate types, while its cold waters are classified as calcium-bicarbonate and magnesium-bicarbonate types. The water itself has outlet temperatures of about 35 °C (95 °F), and it contains various cations (Ca2+, Mg2+, Na+, Si4+, K+, and B3+) and anions (HCO3-, SO42-, Cl-, F-, and NO3-) as well as detectable amounts of radon.
Potential Health Benefits of Hot Springs
Bathing in mineral waters may provide health benefits, particularly to the skin, cardiovascular system, metabolism, and mental health. Persian mineral waters have been shown to help reduce psoriasis while a Nepalese hot spring has led people to report a temporary reduction in musculoskeletal pain due to its relatively high sulfate and chlorine content.
Bathing in mineral waters may provide health benefits, particularly to the skin, cardiovascular system, metabolism, and mental health.
There is also research suggesting that bathing in water with hydrogen sulfide (despite it being a poisonous gas) can reduce inflammation from mycoplasma (a type of bacteria) and bathing in water with salt-bromide-iodine can have a mild anti-inflammatory effect on the airways.
Health Promotion through Hot Springs (Japan)
Japan is known for its bathing culture, with a daily bath at home or at public bathhouses (sentō) still being common, along with its numerous hot springs (onsen) and inns (ryokan) with baths across the country. Even monkeys take part in the comfort of hot springs!
Japanese researchers have found hot spring bathing habits to be associated with lowering blood pressure, enhancing sleep quality, and elevating mood and feelings of well-being. However, elderly bathers or those with heart issues should be extra careful of changes in their blood pressure and get out of the water if they start to feel dizzy or lightheaded.
Japanese researchers have found hot spring bathing habits to be associated with lowering blood pressure, enhancing sleep quality, and elevating mood and feelings of well-being.
Examples of hot springs include the Kurokawa Onsen in Kyushu in a forest setting, private and outdoor onsen in Hakone (southwest of Tokyo), and the Toyotomi Onsen in Hokkaido. Notably, the Toyotomi Onsen has been approved by the Ministry of Health, Labour and Welfare as a collaborative-type health promotion facility, which permits Japanese citizens to deduct some of the costs as medical expenses on their income taxes.
As of November 2023, there are a total of twenty-two hot spring-related health promotion facilities in Japan [website in Japanese], including the Nagayu Onsen Gozenyu in Oita Prefecture and Gero Onsen Suimeikan in Gifu Prefecture.
Although Japanese springs are generally known for their mineral content, the Misasa Onsen is known for its high concentration of radon. There is a study investigating associations between radon hot spring bathing and health conditions for a sample (>5,000) of Misasa residents, concluding that those who bathed in a radon hot spring more than once a week were associated with higher self-rated health and alleviation of hypertension and gastroenteritis. Low doses of radon in balneotherapy for rats using water from Tskaltubo spring was also found to result in decrease of anxiety in rats. However, radon hormesis or radon therapy should be handled with caution, and one should consult their physician of the risks of this type of treatment.
Hot Springs in National Parks (US)
In the US, hot springs can be found in Yellowstone National Park (in Wyoming, Idaho, and Montana) and Hot Springs National Park (in Arkansas).
Yellowstone National Park has hot springs that are scalding hot and should not be touched, but the Yellowstone Hot Springs resort offers natural mineral bathing. Ten hot springs from Yellowstone were found to be categorized into four groups: travertine-precipitating, mixed-alkaline-chloride, alkaline-chloride, and acid-chloride-sulfate.
Likewise, Hot Springs National Park in central Arkansas does not offer outdoor bathing, but visitors are allowed to touch some outdoor thermal water, drink from thermal spring fountains, and visit two bathhouses to soak in the thermal water. The temperature of water arriving at the surface is roughly 143 °F, which needs to be cooled before the capacity of over 600,000 gallons per day can be distributed for public use.
Bathing at Home
For those who can't travel to hot springs or to a spa, bathing at home can offer respite after a long day of work or exercise. Recipes for mineral baths at home typically involve some combination of salts, essential oils (for use in aromatherapy), herbs, and other ingredients. However, caution is advised when concocting recipes at home, as some commercial salts were found to be contaminated with microplastics in 2018. In addition, essential oils should be diluted and care should be taken to avoid direct contact with one’s skin.
*Rainer Fuchs is a freelance journalist working mainly on topics pertaining to health and issues on environmental sustainability.