Salt Therapy (Halotherapy)

Subterranean settings and early use

A review dates modern salt therapy to salt mines and caves in Europe and Russia from the early nineteenth century. The 2001 Cochrane review of speleotherapy for asthma, which covers underground treatment in caves and mines, lists centers in Austria, Italy, the Czech Republic, Russia, Ukraine, Romania, Poland and Kyrgyzstan, with settings ranging from cold limestone caves to warm radon-rich galleries, and stays from one-hour visits to residential programs.

A 2025 study notes that a German reef limestone cave at Ennepetal was listed in a national spa directory in 1954. The sources reviewed for this article did not provide a verifiable account of individual founders such as the German physician Karl Hermann Spannagel, or of the early physician associated with the Wieliczka salt mine in Poland, so no dates or attributions for them are given here.

Above-ground halochambers

Halotherapy emerged as an above-ground alternative designed to reproduce a salt cave microclimate in a controlled room. A 1995 report by Chervinskaya and Zilber, from Russian institutions, describes sessions of dry sodium chloride aerosol in 124 patients with respiratory diseases, with courses of 10 to 20 daily one-hour sessions. A 2021 review cites a 1997 Russian publication on its clinical use, which suggests that development of halochambers is closely tied to Russian research, though the sources reviewed do not state who first built one.

A 2014 review noted that commercial halotherapy centers were increasing in Australia, the United States, Europe and Canada. The sources reviewed do not give a reliable account of when salt rooms began to appear in spas and wellness settings.

Speleotherapy and halotherapy

A 2021 review defines speleotherapy as aerosol therapy in naturally occurring salt environments such as salt caves, and halotherapy as aerosol therapy in any salt-enriched environment, including halochambers and home devices. The term salt therapy is used for both, and for treatments in rooms with salt-covered walls. Naming a session salt therapy therefore says little about whether a dry aerosol is actually generated, at what concentration, or for how long.

One review describes halotherapy as inhalation of natural sodium chloride in a controlled environment with air temperature of 18 to 24 degrees C and relative humidity of 40 to 60 percent. The 1995 report gave particle sizes of 2 to 5 micrometers and densities that varied from 0.5 to 9 milligrams per cubic meter, depending on the disease.

Dry aerosol versus nebulized saline

Nebulized hypertonic saline is a different intervention. It is a liquid solution, commonly 3% to 7% in cystic fibrosis trials, delivered with a nebulizer under clinical direction. The Cochrane review of its use in cystic fibrosis is included here only as a comparator, since its findings concern a different delivery method, a different dose and a different condition than a salt room. A separate trial in COPD used a handheld inhaler of dry salt powder, which is also distinct from a halochamber.

Halochamber sessions

In halochamber studies a generator disperses dry sodium chloride particles into a room while participants rest. In the Israeli pediatric pilot trial, children with mild asthma attended 14 sessions over 7 weeks, in a salt room either with or without a halogenerator, so that the comparison group sat in a similar room without the generated aerosol. The 1995 report described courses of 10 to 20 daily sessions of one hour. Session length, concentration and number of sessions are not standardized across the studies reviewed.

Underground programs

Subterranean programs combine time underground with other components. In a Polish trial in the Wieliczka Salt Mine, people with COPD took part in pulmonary rehabilitation underground or on the surface. In a trial from Austria, adults took part in eight 1.5-hour cave sessions plus winter exercise, compared with exercise alone. A 2026 multicenter trial gave six two-hour sessions over three weeks in caves in Germany, Austria and Italy alongside standard drug therapy. Because exercise, rehabilitation and travel are bundled with the underground setting, effects cannot be assigned to the salt air alone.

Uses described by practitioners and users

Reviews describe halotherapy and speleotherapy as used as an addition to conventional care for asthma, COPD, sinus conditions and other airway conditions, with proposed actions including effects on mucus clearance and airway inflammation. A 2016 charity article noted that the mechanism is uncertain and that proposed explanations, such as killing microorganisms, reducing inflammation or lowering mucus production, were not established.

What users report

A survey of 303 adults in three southern Polish cities found that most respondents knew of salt caves, and that among those who had bought at least three sessions, throat, larynx and sinus problems were commonly named as reasons. Most felt better after sessions, which are self-reports and do not measure effect. The survey did not assess whether reported improvement exceeded what rest, time away from polluted air or expectation might produce, and it did not follow any clinical outcome.

Systematic reviews

The 2001 Cochrane review of speleotherapy found three controlled trials involving 124 children with asthma, only one of reasonable quality, and concluded that the evidence did not permit a reliable conclusion. A 2014 review of halotherapy for COPD found four studies, one randomized, and concluded that recommendations for its use could not be made. A 2022 meta-analysis of 21 trials of rock salt aerosol alongside conventional therapy reported higher lung function measures than in controls, but graded its evidence as very low to low quality and called for confirmation.

The clinical comparator reviewed here, a 2023 Cochrane review of nebulized hypertonic saline in cystic fibrosis, included 24 trials with 1,318 participants. It reported very low certainty about lung function at four weeks, and many trials were at high risk of bias because participants could taste the solution. These findings concern cystic fibrosis only. The searches run for this article did not locate a Cochrane review of salt rooms.

Trials of rooms, mines and caves

In the pediatric pilot trial, bronchial hyper-responsiveness improved in the halogenerator group and not in the control group, while spirometry and exhaled nitric oxide did not improve, and some quality of life scores did. The Wieliczka trial of 42 people with COPD reported greater improvement in symptom and walking scores with underground rehabilitation than with surface rehabilitation, with effects described at six months. The Austrian trial of 41 adults found improvement in both groups, with no significant difference in the main inflammation marker.

In the 2026 multicenter trial of 208 adults, the asthma primary endpoint, exhaled nitric oxide, was unchanged, while asthma control and quality of life scores improved. A 2025 study found no benefit in post-COVID-19 syndrome, and a 2026 crossover study found no difference in mucociliary clearance between inhaled dry salt and an empty inhaler. Most trials are small and unblinded or only partly blinded, and results vary by outcome.

Reported adverse events

Adverse-event reporting is sparse. A 2021 review reported no adverse events in the asthma studies it covered, and the 2014 COPD review did not discuss safety. The meta-analysis of rock salt aerosol noted that three of its trials reported adverse reactions. The Austrian cave trial reported none, and the 2026 multicenter trial reported two upper respiratory infections possibly related to therapy and no serious events. The dry salt crossover study reported no significant adverse effects, but noted that the salty taste limited blinding.

The sources reviewed did not report bronchospasm or airway irritation in salt rooms in a form that could be summarized here. Because small trials are poorly suited to detecting uncommon harms, absence of reports is not evidence of absence. The same 2021 review also describes hypertonic saline bronchial challenges used as a diagnostic tool in asthma and vocal cord dysfunction, and a Cochrane review notes a trial in which mannitol was reported as more irritating than hypertonic saline.

Care boundaries

A 2016 charity article raised concern that warm rooms could support bacterial growth and advised that people discuss salt therapy with a doctor. The sources reviewed do not specify contraindications, hygiene standards or training standards, and no statutory regulation or training standard was found in them. People with chronic airway disease, including asthma, COPD and cystic fibrosis, should not delay or replace prescribed treatment with salt therapy.