What is a Sulphur Spring?
A sulphur spring contains total sulphur (S) at 2 mg or more per kilogram of spring water. Two subtypes exist: the hydrogen sulphide type (H₂S dominant) and the sulphur type (HS⁻ dominant).
Although clear at the source, the water oxidizes in air to produce milky-white, blue, or greenish turbidity. The unmistakable boiled-egg smell of hydrogen sulphide is a beloved hallmark of Japanese hot springs — Manza Onsen (Gunma) and Shiobara Onsen (Tochigi) are famous examples.
Indications for Bathing
- Atopic dermatitisThe hydrogen sulfide in these springs may help control factors that worsen this condition by strongly suppressing the growth of surface bacteria like Staphylococcus aureus. The water's keratolytic properties also help remove old skin cells and promote renewal. Bathing is best during remission, as it can be irritating during severe flare-ups.
- Plaque psoriasisThe sulfur components in the water are thought to help manage chronic skin inflammation by inhibiting the metabolism of pathogenic microbes. This bactericidal action, combined with a keratolytic effect that helps soften and remove built-up skin cells, may help alleviate symptoms of this condition.
- Chronic eczemaSulfur springs may offer relief by addressing key symptoms of chronic skin inflammation. The water's bactericidal properties can suppress surface bacteria that may aggravate the condition, while its keratolytic effect helps remove old, flaky skin and encourage renewal.
- Epidermoid suppurationThis refers to pyoderma, or pus-forming bacterial skin infections. The strong bactericidal effect of sulfur springs is the primary mechanism of action, as the sulfur components are believed to inhibit the metabolism of pathogenic bacteria and help control the infection.
For the hydrogen sulphide type*, peripheral circulatory failure is added to the above indications.
Indications for Drinking
- Impaired glucose tolerance (diabetes)As a recognized drinking indication by Japan's Ministry of the Environment, ingesting sulfur water may help manage blood sugar. The hydrogen sulfide is thought to stimulate the pancreas, potentially promoting insulin secretion. This can be beneficial for those with impaired glucose tolerance.
- Dyslipidemia (high cholesterol)Drinking water from sulfur springs is also officially indicated for those with high cholesterol. The dissolved sulfur compounds are believed to have a positive effect on lipid metabolism. This action may help lower levels of LDL ('bad') cholesterol in the body.
How to Bathe in a Sulphur Spring
- Remove silver jewelry (rings, necklaces, watches) before bathing — sulphur causes blackening (silver sulphide).The sulfur compounds in the water, such as hydrogen sulfide, will chemically react with silver, causing it to tarnish and turn black. This process forms silver sulfide, which is difficult to remove. Be sure to take off any silver accessories to prevent permanent discoloration.
- For skin condition improvement, pat dry without rinsing to keep the antibacterial components on the skin.For conditions like atopic dermatitis or chronic eczema, the spring's sulfur components offer a strong bactericidal effect. By not rinsing with fresh water and gently patting dry, you allow these therapeutic elements to remain on your skin, helping to suppress bacteria and promote healing.
- Hydrogen sulphide collects at low levels — even outdoors, be mindful of ventilation.Hydrogen sulfide gas, the source of the characteristic 'rotten egg' smell, is heavier than air and can pool in low-lying, poorly ventilated spaces. Inhaling it in high concentrations can be dangerous, so always be aware of air circulation, even in outdoor baths, to ensure safety.
Related Onsen Facilities
References
Famous Onsen Areas with Sulphur Spring
Check access and tourist information on each onsen area column
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