The term “spa” likely originated in the 1620s from the name of an Eastern Belgium town known for its hot mineral springs. The practice, however, likely goes back to at least the Romans. It makes sense that in a time before modern medicine, before even the basics of biology were worked out, people would seek cures to common ailments and injuries. Soaking in warm water can certainly feel good, and ease sore muscles, so that’s an obvious place to start.

In the absence of more sophisticated knowledge, people relied mostly on simplistic notions, such as purity and balance, to address their problems. People with tuberculosis or other respiratory problems were often sent to the mountains, to breathe in the pure air in hopes it would heal them.

Of course every human need and tendency is exploited by someone for profit. Spas quickly became an industry, one with a great deal of persistence. Wellness spas are thriving today, even in our era of modern medicine, often with the same old claims of balance and purity. Spas are a triumph of marketing, selling an eclectic mix of holistic nonsense to the worried well with disposable income.

I have to say the marketing is brilliant – spas have positioned themselves as a pleasant experience with vague health benefits and a symbol of beauty and status. I even know some very skeptical and scientific people who go in for the first and third features, while ignoring or downplaying the whole medical pseudoscience thing as just a necessary annoyance. (Perhaps there is a niche for a pseudoscience-free spa, but probably not or else it would already exist.)


Spa owners are always on the lookout for the latest fad, trend, or exotic pseudoscience they can incorporate into their offerings. It’s good to stay ahead of the competition by being the first to jump on a new health fad. Spa claims also mesh seamlessly with the world of alternative medicine, which is also largely based on vague health claims deriving from notions of balance and natural purity. The term “holistic” is thrown around a lot, to the point that it is devoid of all meaning. It is just a feel-good marketing term.

One recent to the list of spa pseudoscience is halotherapy. This basically consists of sitting in a room lined with rock salt – a salt cave. Sitting in a natural salt cave, popular in Poland, is called speleotherapy (yes, that’s the same root as spelunking). But if there are no natural salt caves around, no worries, you can make an artificial one.

What will sitting in a room lined with salt do for your health? At this point, any regular reader of SBM can probably make up the list themselves. Organic spa magazine tells us:

The calming and detoxifying effects of halotherapy can support the immune, nervous and lymphatic systems. Additional benefits are reduced stress and headaches, increased energy, and better sleep patterns. Salt ions purify the air and may increase lung capacity and reduce physical ailments for adults, children and athletes. Treatments are recommended to help keep the body healthy during flu or allergy seasons.

Like all such fake treatments, it’s good for what ails you. The list of claimed benefits is long enough to essentially include everyone, in order to maximize the potential target customer base. Some spas are careful not to make any actual health claims, using the pseudoscience buzzwords of “detox” and “supports X function.”

Some, however, will make specific claims. Since halotherapy “works” because of the negative ions and trace minerals users are allegedly breathing in, marketing is often targeted at respiratory problems. One company, The Salt Cavern, is even more ambitious. They claim halotherapy is good for:

• chronic bronchitis • asthma • hay fever • ear infection • breathlessness, chest tightness • pneumonia after acute stage • bronchiectatic disease • smoker’s cough (including secondary smoke) • cough with viscous sputum discharging with difficulties • dry, paroxysmal cough with distant rates • dry rales (mostly with low tone) changing its localization during auscultation • frequent acute disorders of respiratory tract • pharyngitis • multi-chemical sensitivity syndrome • sinusitis/sinus inflammation • respiratory infections • respiratory allergies to industrial and household pollutants • rhinitis • tonsillitis • eczema and more.

There is, as you might suspect, a complete lack of any credible scientific evidence for any of these claims. That is not how the spa (and alternative medicine) world works. They just make up nice-sounding explanations that seem wholesome, and then make unsubstantiated claims. They will back this up, of course, with anecdotes.

Some spa entrepreneurs will hunt for any scientific study they can use to support their therapy, and then such claims get spread around. In the case of halotherapy promoters will often cite a 2006 NEJM study that found that inhaling hypertonic saline mist may help improve symptoms in patients with cystic fibrosis. They extrapolate from this one study to support the claim that sitting in a salt cave is good for all respiratory symptoms.

First, sitting in a salt cave, even if they add some salt to the air, is not the same as breathing in a hypertonic mist. Further, in the study patients were pretreated with a bronchodilator. And of course cystic fibrosis is a very specific illness, and any results do not necessarily apply to other respiratory disorders.

But all these sciencey details don’t matter, if your only interest in creating the impression of being science-based for marketing purposes.

In the end halotherapy has no prior plausibility for the health claims made for it, and there is no evidence to support those claims. One feature that does set it apart from many spa fads, however, is that building a salt room does take a bit of investment. It’s not like spa reflexology, which uses existing infrastructure. That investment likely means that halotherapy will be around for a while, likely with an ever expanding list of claims, as spa owners try to capitalize on their investment.


Posted by Steven Novella

Founder and currently Executive Editor of Science-Based Medicine Steven Novella, MD is an academic clinical neurologist at the Yale University School of Medicine. He is also the host and producer of the popular weekly science podcast, The Skeptics’ Guide to the Universe, and the author of the NeuroLogicaBlog, a daily blog that covers news and issues in neuroscience, but also general science, scientific skepticism, philosophy of science, critical thinking, and the intersection of science with the media and society. Dr. Novella also has produced two courses with The Great Courses, and published a book on critical thinking - also called The Skeptics Guide to the Universe.