Balneotherapy Overview

Man in bath
A hot bath can feel really good after a long day. Is it actually good for your health, too?
Steve Mason/Getty Images

In his 1993 novel "The Road to Wellville," T.C. Boyle lampoons Dr. John Harvey Kellogg, the cornflake inventor who also founded a spa in Battle Creek, Mich. The novel is set in 1907-1908 and paints an unflattering picture of both Kellogg and the pseudoscientific treatments he recommends for his "sanitarium" guests. One such therapy is known as the sinusoidal bath, which involves placing a person in tepid water and applying an electric current to the bath. This treatment produces muscular contractions in the patient that are supposed to relieve a number of symptoms. In Boyle's book, the therapy results in the electrocution of one of the spa's residents.

Most modern spa owners and therapists would likely cringe at such an outlandish scene. They know that the therapeutic use of water, or balneotherapy, is a safe and time-tested treatment. Almost all of them have patients who claim that balneotherapy can heal a variety of ailments, from eczema to rheumatoid arthritis. But the jury is still out on the scientific validity of these claims, and the mechanisms of action remain unclear. One thing is very clear: Regardless of scientific evidence proving their efficacy, water-based therapies provide a calming, soothing experience that many consumers appreciate.


Indeed, balneotherapy is a major force driving the growth and expansion of spas. Consider these statistics about the U.S. spa industry from the International Spa Association:

  • As of June 2008, there were 18,100 spas.
  • The number of spa locations has grown at an annual average of 20 percent in the last eight years.
  • There are more than 32 million active spa-goers.
  • In 2007, there were 138 million spa visits, generating $10.9 billion of revenue.
  • One in four Americans has been to a spa.
  • In June 2008, there were 303,700 full-time, part-time and contract employees working in the spa industry.

To understand how balneotherapy contributes to these trends, we need to understand the topic more thoroughly. That means taking a deep dive into both the myth and the medicine behind this favorite spa treatment. Our first order of business is clearly defining balneotherapy.


Balneotherapy Defined

Everyone agrees that balneotherapy involves water. What they don't always agree on is the source and exact chemical makeup of the water. Purists use a much narrower definition of balneotherapy that has three key elements:

  • Temperature: The temperature of water for balneotherapy must be at least 68 degrees Fahrenheit (20 degrees Celsius), although it is often much warmer, at 93 degrees Fahrenheit (34 degrees Celsius).
  • Mineral content: Balneotherapy requires water containing dissolved materials at a concentration of at least 1 gram per liter. The dissolved substances most often include salts, sulfur compounds or gases.
  • Natural occurrence: Natural springs are the preferred source for those seeking balneotherapy. A spring forms when an aquifer fills to the point that the water overflows onto the land surface. They range in size from small seeps to huge pools, and they vary greatly in their mineral content. Examples of natural springs include Great Pagosa Hot Springs in Colorado, Warm Mineral Springs in Florida and the Kangal Hot Springs in Turkey.

Broader definitions also exist. For example, Dorland's Medical Dictionary defines balneotherapy as the use of baths in the treatment of disease. A bath, in this case, refers to immersion in any kind of water at any temperature. Sometimes, immersion isn't even required. The application of a hot or cold wrap can be considered a therapeutic use of water, too. In this broader sense, balneotherapy is also known as hydrotherapy and includes:


  • Full-body baths (in a tub or natural body of water)
  • Arm and foot baths
  • Sitz baths (immersion of the hips)
  • Steam baths or saunas
  • Motion-based therapies involving hot tubs or whirlpool baths
  • Saline baths
  • Wet compresses (hot or cold)
  • Douches
  • Mudpacks

Balneotherapy has been popular for centuries, both as a way to promote relaxation and to treat certain ailments. Up next, we'll examine the history of water-based therapy, from the Roman bath to the modern spa.


History of Balneotherapy

Woman at spa in Baden-Baden, Germany
Would the Romans find the Caracalla Therme spa in Baden-Baden, Germany, refreshing?
Slim Aarons/Getty Images

Using water to soothe and heal is an ancient practice. Archaeologists have found remains of bathing rooms in the palace of Knossos that date from 1700 B.C., indicating that the Greeks appreciated the effects of a good, long soak. The Greek physician Hippocrates (460-377 B.C.) also wrote extensively about the healing power of water. He advocated the use of saline baths and regularly immersed his patients in seawater to cure several ailments, including aching muscles and arthritis.

Ancient Egyptians embraced water-based therapies just as enthusiastically. Cleopatra (69-30 B.C.) visited the Dead Sea to soak in its mineral-rich waters and may have established pharmaceutical and cosmetic factories near its shores. But it was the Romans who took bathing to a new level of sophistication. At first, Roman baths were small, private and unobtrusive. Then came larger neighborhood baths, which were followed by massive public baths. The Baths of Caracalla represented the pinnacle of the Roman bathing experience. Constructed between A.D. 206 and A.D. 217, the Baths of Caracalla covered 27 acres and could accommodate 1,600 people at a time.


Eventually, the Roman Empire collapsed and, with it, interest in balneotherapy. The last Roman baths were abandoned by about A.D. 537. By the time the Black Death swept through Europe in the 1340s, public bathing had all but stopped. In addition to fears associated with disease transmission, the strict moral code of the Roman Catholic Church discouraged people from visiting public watering places.

Then, in the 1800s, came a renaissance. Vincent Priessnitz, an Austrian peasant, used cold-water therapy to heal wounds he obtained when a heavy cart rolled over him. Word of his recovery spread, and thousands of people came to him. He treated 1,600 patients in 1840 and, three years later, published "The Cold Water Cure," a book that spread his treatment philosophies to thousands more. Sebastian Kneipp, a German priest, picked up the baton and continued to advance balneotherapy. He improved some of Priessnitz's techniques and began to add herbs to the water.

Priessnitz and Kneipp gave rise to the rebirth of spas in the Victorian era. Hot springs were found and developed, often at mountain retreats with breathtaking views. Medical practitioners often staffed these spas and dispensed various water-based treatments. Americans treated in European spas returned home with stories of water's healing effects. Soon, similar spas emerged in the United States. As they became more popular, the spas evolved into spa resorts, featuring world-class restaurants, entertainment and recreational facilities.


The Physiology of Balneotherapy

People at public bath
People crowd in this hot spring bath for its medicinal benefits in Garmisch Gul-Ardabil, Iran.
Majid Saeedi/Getty Images

Although the mechanisms by which spa therapies alleviate certain diseases are still being deciphered, most scientists agree that they probably have chemical, thermal, mechanical and immunological components. Let's look at each in more detail.

Chemical effects. The chemical composition of water used in balneotherapy varies greatly, depending on the source. Sulfur, present in "sulfur waters" as a free or combined ion, is one of the most common chemicals in mineral spa waters. It is known to promote keratolysis, the loosening and shedding of the outer layer of the skin, which can be effective in treating certain skin conditions, such as acne. It also possesses antibacterial and antifungal properties, believed to be the result of sulfur interacting with reactive oxygen molecules in the epidermis to produce an acidic environment that prevents microbe growth.


Other minerals act differently. Magnesium, for example, inhibits the synthesis of polyamines, essential molecules in eukaryotic cells. Polyamines are thought to play a role in the development of psoriasis. When patients with psoriasis soak in water with high magnesium concentrations, they often see an improvement in their conditions.

Thermal effects. Hot water has several beneficial effects. Heat increases the concentration of beta-endorphin, a natural painkiller. In addition to its analgesic effects, beta-endorphin boosts the immune system, slows the growth of cancer cells and increases relaxation.

Heat also prevents inflammation, probably by increasing the secretion of cortisol and catecholamines, two hormones produced by the adrenal glands. For this reason, doctors often prescribe hot-water baths to treat inflammatory conditions, such as arthritis or dermatitis, as well as certain autoimmune diseases.

Mechanical effects. An immersed body experiences a force applied by the water on all sides. This force is known as hydrostatic pressure and can have many benefits. In the lower legs and feet, which are deeper and feel a greater force, it reduces swelling, decreases blood pooling and helps to return venous blood to the heart. Hydrostatic pressure may also contribute to lower working heart rates while in the water.

Buoyancy, the upward vertical force of water on a submerged body, is another important mechanical effect. Buoyancy counteracts the effects of gravity and reduces compression of the joints. Many people who can't exercise on land bearing their full weight can exercise vigorously and comfortably in water.

Immunological effects. Some research suggests that trace elements present in mineral water are absorbed through the skin and affect the immune system. Sulfur water is believed to inhibit proliferation of certain lymphocytes and their ability to produce and release cytokines. Cytokines are proteins that help regulate the immune response. For example, patients with rheumatoid arthritis produce an excess of interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF-alpha), two important cytokines. By inhibiting IL-1 and TNF-alpha, sulfur water may relieve symptoms of arthritis and other inflammatory diseases.


Clinical Trials Evaluating Balneotherapy

Much of our knowledge about how balneotherapy works physiologically has come from a variety of studies and clinical trials conducted since the 1950s. Unfortunately, conclusive data has been slow to emerge. One reason has to do with the difficulty in setting up "blinded" studies. Blinding refers to the practice of keeping both researchers and study participants in the dark about who is receiving the treatment under study and who is receiving the placebo treatment. In the case of balneotherapy, it's difficult to veil the treatment study when the water used in the study is hot, buoyant or smells of sulfur.

Still, researchers have pushed on, doing their best to reduce observer bias, reporter bias and the placebo effect. To date, the most conclusive studies demonstrating the therapeutic effect of balneotherapy have been those focused on musculoskeletal disorders. A recent review of relevant randomized controlled studies revealed that balneotherapy resulted in statistically significant pain improvement in patients with rheumatic diseases and chronic low back pain. Rheumatic diseases affect joints and connective tissues and include more commonly known conditions such as rheumatoid arthritis and osteoarthritis. They also include fibromyalgia, a syndrome of conditions characterized by widespread pain in muscles and connective tissues, and ankylosing spondylitis, a chronic inflammatory disease of the spine and pelvis.


Another promising area of research has focused on the effects of balneotherapy on dermatological conditions. There is growing evidence that water-based treatments benefit patients with psoriasis, a condition marked by uncontrollable skin cell growth, and atopic dermatitis, a type of eczema in which the skin becomes irritated and inflamed. Scientists are also studying balneotherapy as a treatment for acne, rosacea and seborrhea.

Over the next few years, research may show that balneotherapy can do much more than treat ailments of the skin, bones and muscles. Studies are already under way to investigate the effectiveness of water as a therapy for cardiovascular and neurological disorders. For example, deep breathing exercises conducted in heated pools may be beneficial to people with chronic obstructive pulmonary disease (COPD). And very preliminary results from one trial indicate that repeated sauna therapy may protect against oxidative stress, which leads to the prevention of atherosclerosis. If this research bears fruit, the medical advice we are likely to hear in the future is, "Take a hot bath and call me in the morning."


Lots More Information

Related HowStuffWorks Articles

  • "Balneotherapy." Beth Israel Deaconess Medical Center, Conditions A-Z. (Sept. 3, 2009)
  • "Balneotherapy." Healthline. (Sept. 3, 2009)
  • Contey, Genevieve. "50 Top Wellness Destinations: Glossary." National Geographic Traveler. (Sept. 3, 2009)
  • Falagas, M.E., E. Zarkadoulia and P.I. Rafailidis. "The Therapeutic Effect of Balneotherapy: Evaluation of the Evidence from Randomised Controlled Trials." International Journal of Clinical Practice, published on Medscape. July 21, 2009. (Sept. 3, 2009)
  • "Hydrotherapy, Balneotherapy." Aetna InteliHealth, Complementary and Alternative Medicine. (Sept. 3, 2009)
  • Matz, Hagit, Edith Orion and Ronni Wolf. "Balneotherapy in dermatology." Dermatologic Therapy. Vol. 16, 2003.
  • Sinclair, Marybetts. Modern Hydrotherapy for the Massage Therapist. Lippincott Williams & Wilkins. 2007.