Bathing in warm mineral water is the oldest continuously practised treatment in Europe: Roman baths, Ottoman hammams, Habsburg spa towns, Hungarian bath culture. Because it is old, it attracts both unearned dismissal and unearned claims.
What is balneotherapy?
The medical use of mineral or thermal water — bathing, drinking cures, mud and peat packs, inhalation — usually over a course of days or weeks rather than a single visit. Waters are classified by what they carry: sulphur, salt, carbon dioxide, radon, or simply heat. In Germany, Austria, Hungary and Italy, courses like these have been prescribed within the health system for generations.
Does it actually work?
For pain and joint function, the trials are cautiously encouraging: bathing courses can reduce pain and improve function in osteoarthritis and chronic low back pain, and some skin conditions improve with certain waters. The effects are modest and the studies often small and hard to blind — you cannot give someone a placebo hot spring. What thermal water does not do is remove "toxins" or cure disease, and any spa that says otherwise is not describing balneotherapy.
Is the mineral content the active ingredient?
Honestly, nobody has cleanly separated the water's chemistry from the heat, the buoyancy that unloads painful joints, the movement, and a week away from work. That is a real limitation of the evidence — and also a reason the courses help people. A cure town is a machine for rest.
When should I be careful?
Heat is a load on the circulation. Cardiovascular disease, uncontrolled blood pressure, pregnancy and alcohol all change how a hot pool should be used — shorter sessions, cooler water, or not at all. Radon waters carry their own discussion. If you have a condition, the sensible order is doctor first, booking second.
Where do I find thermal centres?
Thermal springs and bath houses are one of the best-mapped categories in OpenStreetMap, which is why this directory can show so many of them. Start with the thermal centres in the catalogue, or open the map and search an area you are travelling to.
Is this medical advice?
No. It is background for choosing where to go. If you have a heart condition, are pregnant, or are being treated for anything, ask your own doctor how — and whether — to use thermal bathing.