Water Therapy

Updated by Linda Rath | July 6, 2023

Soaking in warm water, with or without minerals, is one of the oldest forms of medicine. And there’s good reason why this practice has stood the test of time. Research has shown it can help all kinds of musculoskeletal complaints, including fibromyalgia, arthritis pain and low back pain.

“Water is wonderful,” says Carol Huegel, a physical therapist in Gainesville, Florida. “It reduces the force of gravity that’s compressing the joint; offers 360-degree support for sore limbs and can increase circulation and decrease inflammation.”

There are plenty of studies to back up Huegel, with one important caveat. Most research has focused on the healing effects of natural mineral springs, or balneotherapy, a common medical treatment for arthritis in many parts of the world. What Huegel and others in the U.S. usually mean is hydrotherapy, which uses warm tap water in a spa or tub. Terminology may not matter to anyone but researchers, because both seem to be effective.

Water Works

A number of meta-analyses comparing the results of many different studies have looked at balneotherapy for a range of rheumatic diseases, including rheumatoid arthritis, osteoarthritis, spondyloarthritis and psoriatic arthritis. Although results have been mixed, outcomes are generally more positive than negative. Some poor results may be due more to poor quality of the studies. In almost all cases, balneotherapy improved quality of life for people with arthritis, especially when combined with exercise, physical therapy or other nondrug treatments known to improve symptoms.

One randomized controlled trial compared two groups of older adults with knee osteoarthritis (OA). One group received physical therapy plus mineral baths; the other received physical therapy alone. By the end of the study, nearly 99% of the mineral bath patients had improvements in pain, function and quality of life compared to 89% of the PT-only group.

Why Water Works

Exactly why balneotherapy is so effective isn’t entirely clear.  Some research suggests the temperature, pressure and mineral content of the water help relax muscles, improve joint mobility and stimulate the release of important hormones and beta-endorphin, a natural pain blocker. In one study, 40 patients with OA spent 20 minutes a day for 15 consecutive days in thermal spring water that reached temperatures of 100 to 104 degrees F. Researchers attributed a notable improvement in pain and function to a decrease in a biolipid (natural fat) that’s involved in the immune response and production of immune cells.

How To Get a Spa Experience at Home

Keep water on the warmer side. In studies of balneotherapy and rheumatoid arthritis, patients spent about 20 minutes in natural mineral water that was 95 to 100 degrees F. Physical therapist Huegel keeps her therapy pools a little cooler, about 92 to 96 degrees F., believing it’s safer, especially for people with heart disease.

Don’t just sit there. A warm bath stimulates blood flow to stiff muscles and joints, making it an ideal place to do some gentle stretching. Paul Ingraham, a retired massage therapist in Vancouver, Canada, likes to use a tennis ball to knead away his own low back pain. Hold the ball between the small of your back and the bottom or back of the tub. Lean into the ball and roll it against knotted muscles.

Add salt. Adding Epsom or Dead Sea salts to your tub can help replicate mineral-rich thermal baths. Epsom salts, which are high in magnesium, are available in most drug and grocery stores. Look for Dead Sea salts online. Researchers at the University of Birmingham in the U.K. suggest using about three cups of Epsom salts for a full tub of water.