The use of hot and cold baths (balneotherapy) for treating illnesses goes back to the dawn of civilization. In recent centuries, the use of hot springs and water in other forms was popularized by early practitioners of what later would become naturopathy]]> . Out of these practices, a formal system of medicine known as hydropathy developed. Today, mud packs, saunas, and steam baths are often included along with water baths under the general name of balneotherapy.

Certain types of water are often particularly prized by practitioners of balneotherapy. These include sulfur springs and the concentrated salty water of drying lakebeds, such as the Dead Sea (in Israel). Interestingly, hot springs high in the radioactive substance radon are also said by some proponents to possess particular healing properties.


What Is the Scientific Evidence for Balneotherapy?

Although various forms of balneotherapy have undergone some scientific study, none of this evidence is reliable. There are many causes of the inadequacies in the research record, but one is intrinsic and probably not correctable. This is the problem of "blinding."

For the results of a study to be reliable, participants and researchers must be kept in the dark ("blind") regarding who received the treatment under study (the "active group") and who received a placebo treatment (the "control group"). If practitioners and/or researchers know who is in which group, numerous confounding factors take over and produce misleading results. These factors include observer bias, reporting bias, and the placebo effect. The many ways in which these confounders reliably skew the results of unblinded studies are discussed in detail in Why Does This Database Rely on Double-blind Studies?]]> To briefly summarize this complex issue: unblinded studies usually mean little to nothing.

Unfortunately, it's difficult to keep study participants in the dark regarding whether they've taken a hot bath! Some researchers have used ordinary tap water as a comparison against special mineral water. Unfortunately, if, (as was the case in some studies) the active treatment smelled of sulfur, or (as in other studies) it was so dense with minerals that it made the skin tingle and the body float high in the water, participants would have no doubt guessed which group they were in. This would effectively destroy blinding, and, as noted above, fundamentally compromise the study results.

Given these caveats, there is some evidence that balneotherapy of various kinds might be helpful for:

Balneotherapy is also said to be helpful for ]]>eczema]]> , ]]>Parkinson's disease]]> , and numerous other conditions, but for these conditions it lacks even unreliable supporting evidence.


How Might Balneotherapy Work?

If indeed it does work, balneotherapy could act through the effects of heat, both locally (on muscles, joints and skin), and systemically, through absorption of substances, such as sulfur through the skin.

Safety Issues

Excessive immersion in hot baths can be dangerous for pregnant women, young children, those with a heart condition or other serious medical illness, and people under the influence of alcohol or other intoxicating substances.

There are concerns that hot springs high in radon might present cancer risk, though this has not been proven.