A wide range of claims about the benefits of onsen baths for the skin are now circulating, from “opening pores” to “instantly brightening skin.” Some of these claims do have a scientific basis, but other information out there is not necessarily accurate.
When myths and facts get mixed together, it becomes difficult to know what you can truly expect from soaking in an onsen. That is why this article will guide you through the myths and facts about onsen baths and skin health based on research findings, so you can enjoy the onsen experience with the right expectations.
Also Read: The Benefits of Soaking in a Private Onsen for the Body
Four Popular Claims About Onsen Baths and the Skin
Here are some of the most commonly heard claims about the effects of onsen baths on the skin, along with what science has to say about each one.
“Hot Water Permanently Opens Your Pores”
“Hot water permanently opens your pores” is one of the most widely known skincare myths, and it is not exclusive to onsen baths. The fact is, pores do not have muscles. They cannot “open” and “close” like a door.
What actually happens when the skin is exposed to warm water is that the small blood vessels near the skin’s surface dilate and the skin expands slightly. This makes pores appear temporarily larger. Once the skin returns to its normal temperature, the appearance of the pores returns to its original state. No permanent change takes place.
What is genuinely true is that warm water can soften sebum and debris on the skin’s surface, making pores easier to cleanse after a soak. However, that process is very different from “opening pores.”
“The Longer You Soak, the Better It Is for Your Skin”
The logic sounds reasonable enough: if 15 minutes of soaking is good, then 45 minutes must be even better. Unfortunately, your skin does not work that way.
Soaking in warm water for too long can actually strip away the skin’s natural oils that help maintain moisture. The result is skin that feels dry, tight, and more prone to irritation.
Most sources recommend a soaking duration of around 15-20 minutes as the range that provides benefits without compromising the skin’s protective barrier. After soaking, apply a moisturiser promptly to help lock in hydration while the skin is still warm and receptive.
“Minerals in Onsen Water Instantly Brighten the Skin”
The claim that “minerals in onsen water instantly brighten the skin” is not entirely wrong, but it is not entirely right either. The answer depends on what is meant by “brighten.”
Research shows that certain minerals in thermal water do have positive effects on the skin.
A review by Cacciapuoti et al. (2020) identified several mechanisms: magnesium and sulphur support skin regeneration and have anti-inflammatory properties; selenium and strontium help suppress inflammatory markers in skin cells; while silica and calcium bicarbonate help reduce inflammatory reactions in the skin.
However, these effects are not instant, and “brightening” in this context does not mean changing the skin’s colour. Minerals support skin health gradually by reducing inflammation, supporting regeneration, and improving the skin’s barrier function.
Healthier skin naturally appears cleaner and more radiant, but this is a process, not a one-soak miracle.
“All Warm Water Has the Same Effect on the Skin”
Warm tap water and thermal mineral water may both be warm, but they are not the same in terms of composition. The key difference lies in the mineral content.
Cacciapuoti et al. (2020) noted that the therapeutic effects of thermal water depend heavily on the types and concentrations of minerals it contains.
Water rich in magnesium and sulphur has different effects from water rich in potassium or manganese. In clinical studies, the use of thermal mineral water showed more significant results compared to regular tap water for skin conditions such as psoriasis and atopic dermatitis.
That said, this does not mean ordinary warm water offers no benefits. Warmth does help with muscle relaxation and circulation, although for specific skin benefits, mineral composition provides a more pronounced effect.
The Verdict: Myth or Fact?
The widely circulating claims about onsen benefits for skin health can be either myth or fact.
Onsen baths do offer scientifically supported benefits for skin health, primarily through their mineral content, the effects of warmth on circulation, and support for the skin’s barrier function. However, these benefits are gradual and supportive, not instant or transformative.
The most important thing is to enjoy the soaking experience for a reasonable duration, apply moisturiser afterwards, and not expect a single session to dramatically change your skin’s condition.
Consistency and comprehensive care remain the keys to healthy skin.
Also Read: 5 Benefits of Reflexology for a Body That Often Feels Sore and Tired
Get the Benefits of Onsen Combined with Skincare Through the Onsei Flow Ceremony
If you want to maximise the benefits of soaking for your skin, the Onsei Flow Ceremony offers a sequence designed for exactly that.
This 120- or 150-minute ritual combines the Onsei Flow Massage to release body tension, the Ryokucha Body Scrub to remove dead skin cells with green tea antioxidants, and concludes with the Signature Onsen Bath, a soak in a private teak wood tub to close the ritual.
The treatment sequence is designed so that skin that has been exfoliated and muscles that have been relaxed receive the full benefits of the warm mineral soak at the end of the session.
Visit Onsei at our Tebet, Bintaro, or Gading Serpong locations. Book here to experience the ritual firsthand at Onsei.
References
Cacciapuoti, S., Luciano, M. A., Megna, M., Annunziata, M. C., Napolitano, M., Patruno, C., Scala, E., Colicchio, R., Pagliuca, C., Salvatore, P., & Fabbrocini, G. (2020). The role of thermal water in chronic skin diseases management: A review of the literature. Journal of Clinical Medicine, 9(9), 3047.
