Thermal Waters and Thermal Skincare — the Science Behind the Marketing Mist

Thermal waters — a lucrative business from deep in the earth

Few skincare segments lean so heavily on a single ingredient as thermal dermocosmetics. Avène, La Roche-Posay, Vichy, Uriage — each of these brands builds its identity around water from a specific thermal spring in France. But can water — even water from volcanic depths — really be an "active cosmetic ingredient"?

The question deserves an honest answer, because the stakes are high: the thermal dermocosmetics market is worth billions of euros a year.

Mineral content — what sets the different waters apart?

Every thermal spring has a unique mineral profile, something brands are keen to highlight in their messaging. Check the details in our ingredient encyclopaedia.

Avène — low mineralisation, high selenium

The water from Avène (southern France) is a low-mineral-content water (266 mg/l) rich in selenium and silica. Avène positions it as particularly suited to sensitive and atopic skin, emphasising its low irritation potential.

La Roche-Posay — selenium and strontium

The La Roche-Posay spring delivers a medium-mineral-content water with a high selenium content (53 µg/l — one of the highest among thermal waters) and strontium. The brand builds its messaging around antioxidant and soothing properties.

Vichy — high mineralisation, 15 minerals

The volcanic water from Vichy has a high mineral content (5.1 g/l) and contains 15 minerals, including an exceptionally high level of bicarbonates. Vichy positions it as a skin-barrier strengthener.

Uriage — isotonic

The water from Uriage (the Alps) has a mineral content close to isotonic (11 g/l), which the brand presents as offering optimal compatibility with the skin's physiology.

These differences in mineral content are real and measurable. The question is: do they have any clinical significance when applied to the skin?

The scientific evidence — what has actually been proven?

It has to be said in fairness: thermal brands invest in clinical research far more than the average cosmetics manufacturer. The body of published work is substantial, but it needs to be assessed critically:

What has been demonstrated

• Soothing action — thermal waters (especially Avène and LRP) have been shown to reduce redness and itching in studies on people with atopic dermatitis and after dermatological procedures. The results are consistent across multiple studies.
• Antioxidant properties of selenium — at the concentrations found in LRP and Avène waters, selenium shows a protective effect against oxidative stress in in vitro studies on keratinocytes.
• Post-procedure support — several clinical studies confirm the benefits of applying thermal water after laser treatments and chemical peels.

What has not been demonstrated (or only weakly)

• Superiority over ordinary water — surprisingly few studies directly compare thermal water with distilled or saline water under identical conditions. Those that do show small or statistically insignificant differences.
• Mineral penetration — the stratum corneum is an excellent barrier. How much selenium or strontium actually penetrates into the living layers of the skin during brief contact with a mist remains an open question.
• Long-term benefits — most studies are short observations (4–8 weeks). There is no data on lasting effects.

It's worth checking the full ingredient lists of thermal products in the PurScore search engine to see what, beyond the thermal water itself, they actually contain.

Thermal mist — does $15 for water in a spray can make sense?

This is the trickiest question, and the answer calls for some nuance:

The case for

• A pleasant feel on the skin — the cooling and hydrating effect is immediate (though short-lived).
• Help after procedures — when skin is irritated, a gentle mist can bring relief without the risk of further irritation.
• Setting make-up — as a light fixing spray.
• A sterile formula — unlike tap water, thermal water in an aerosol is free of chlorine and contaminants.

The case against

• Water evaporates — and takes moisture from the epidermis with it (transepidermal effect). Without applying an occlusive product after misting, the skin can end up more dehydrated than before.
• Price-to-content ratio — you're paying for water, propellant gas and marketing. A 300 ml bottle of Avène costs around $9–13. A glycerine toner for $4 will give a similar hydrating effect.
• Environmental impact — single-use aluminium aerosol cans place a significant burden on the environment.

Thermal creams and serums — this is where the real value lies

Paradoxically, the greatest value of thermal brands lies not in the waters themselves, but in the cosmetic formulas developed around them. Avène, LRP and Vichy are brands with serious dermatological backing, and they produce some of the best-researched dermocosmetics on the market:

• La Roche-Posay Cicaplast — a regenerating range with panthenol and madecassoside, clinically tested many times over.
• Avène Cicalfate — regenerating creams with copper and zinc sulphate.
• Vichy Minéral 89 — a serum with hyaluronic acid and volcanic water.

In these products, thermal water is just one of many ingredients, and the effectiveness comes from the whole formula, not the water alone. But thermal brands invest heavily in the clinical research behind their products, and that sets them apart in the market. Read more about how to evaluate ingredients in our guide to natural and synthetic ingredients.

Comparing thermal waters — a table

Below is a summary of the key parameters of the most popular thermal waters:

The verdict — marketing built on solid foundations

Thermal waters in skincare are a fascinating case in which the marketing is layered over a real but modest scientific foundation. The minerals in thermal waters do have certain biological properties, but their clinical significance when applied to the surface of the skin is limited.

Is a thermal mist money down the drain? Not necessarily — if you enjoy it and use it wisely (always follow it with an occlusive product). But don't buy it believing that minerals from deep in the earth will rejuvenate your skin. The real value of thermal brands lies in their creams and serums, whose formulas are among the best-researched in dermocosmetics.