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Things to Know Before Getting Into an Onsen! Types of Hot Springs and Their Effects

Depending on the contents of the spring water, hot spring baths (onsen) can have different effects on the body. Knowing more about onsen before visiting Japan, the land of onsen, can help you to better enjoy the experience. Here are the different types of onsen and their effects, as well as where you can find different types of onsen.

What Types of Onsen Are There in Japan?

Home to many volcanoes, Japan is a place where there are many hot springs. Hot springs are defined in accordance to the Hot Spring Law, and classified into one of the 10 known types of onsen depending on the natural chemical components present in the spring water. Whichever the type of onsen, they have certain beneficial effects to health. Here is more detail which onsen type is effective for different ailments.

What are "ailments"?

"Ailments" are defined as health conditions that onsen are effective against. Some common effects of onsen are the relief of chronic muscle and joint aches, rheumatism, arthritis, lower back pains, neuralgia, stiff shoulders, bruises, sprains, muscle stiffness, sensitivity to cold, peripheral circulatory disturbance, indigestion, flatulence, mild hypertension, diabetes, mild hypercholesterolemia, asthma or emphysema, hemorrhoids, autonomic instability, stress-related disorders (insomnia, depression etc.), convalescence, and fatigue recovery. Onsen is said to be good for improving one's health!

Types of Springs That Are Effective For Stiff Shoulders

Simple hot springs, chloride springs, hydrogen carbonate springs, sulfate springs, carbon dioxide springs, ferruginous springs, sulfur springs, acidic springs, radium springs, iodide ion springs

All 10 types of onsen are effective for stiff shoulders. Simple hot springs, defined as spring water containing very little natural chemical components, work especially well for this condition. In Japan, there are many simple hot springs, and due to the mild properties of this type of onsen, it is recommended for the elderly.
There are simple hot springs in Kinugawa Onsen (Tochigi), Hakone Onsenkyo (Kanagawa), Gero Onsen (Gifu), and Beppu Onsenkyo (Oita). It is said that the onsen at these places are good for stiff shoulders.

※Picture below is of Kinugawa Onsen (Tochigi).

Types of Springs That Are Effective For Wounds

Chloride springs, hydrogen carbonate springs, carbon dioxide springs, sulfur springs

Chloride springs contain sodium chloride and have a composition that is similar to sea water. Chloride springs prevent sweat from evaporating, and as such, helps to keep one's body nice and warm. Also, the disinfectant properties of chloride springs make it a popular choice among people recovering from wounds.
Chloride springs can be found in places such as Noboribetsu Onsen (Hokkaido), Yugawara Onsen (Kanagawa), Atami Onsen (Shizuoka), and Shirahama Onsen (Wakayama).

※Picture below is of Atami Onsen (Shizuoka)

Types of Springs That Gives You Smooth Skin

Hydrogen carbonate springs, sulfate springs, sulfur springs

Many hydrogen carbonate springs are alkalic in nature, and helps to exfoliate dead skin and cells, making your skin nice and smooth. For this reason, hydrogen carbonate springs are all called "Bijo No Yu," which loosely translates to "bath water of beautiful women." Also effective for wounds and chronic skin diseases.
Hydrogen carbonate springs can be found in places such as Nyuto Onsenkyo (Akita), Ikaho Onsen (Gunma), Akakura Onsen (Niigata), Myoken Onsen (Kagoshima).

※Picture below is of Nyuto Onsenkyo (Akita)

Types of Springs That Are Effective For Arteriosclerosis

Sulfate springs, carbon dioxide springs, sulfur springs, radium springs

While sulfate springs are effective against arteriosclerosis, depending on the content of the spring water, sulfate springs can be further divided into 3 types. While the effects of these 3 types vary slightly, the common point is that they expand the blood vessels which improves blood circulation, relieving the symptoms of arteriosclerosis. Sulfate springs not only help to reduce blood pressure, but also has a calming effect, thus they are famous for being medically effective onsen. Also good for wounds and skin diseases.
Sulfate springs can be found in places such as Togatta Onsen (Miyagi), Shima Onsen (Gunma), Hakone Gora Onsen (Kanagawa), and Izu Yugawara Onsen (Shizuoka).

※Picture below is of Shima Onsen (Gunma)

Types of Springs That Are Effective For High Blood Pressure

Carbon dioxide springs, sulfur springs, radium springs

Also known as "Shinzo No Yu" (loosely translates to "water of the heart"), carbon dioxide springs help to expand the body's capillaries and improve blood circulation, which, in turn, lowers blood pressure. Also effective for arteriosclerosis, wounds, and burns. Taking a dip inside a carbon dioxide spring also helps to keep your body warm.
Carbon dioxide springs can be found in places such as Michinoku Onsen (Aomori), Tamagawa Onsen (Akita), Yuya Onsen (Gifu), and Nagayu Onsen (Oita). It is also said that carbon dioxide springs are good for lowering blood pressure.

※Picture below is of Tamagawa Onsen (Akita)

Types of Springs That Are Effective For Gynecological Diseases

For chronic gynecological diseases, chloride springs, sulfur springs, radium springs, for menstrual disorders, ferruginous springs

Also known as "Fujin No Yu" (women's spring), ferriginous springs have a high iron content. It is said that the high iron content helps to promote hematopoiesis, and is effective for women with menstrual disorders. A characteristic of this type of onsen is that while initially clear and colorless, the water slowly becomes a rust-red or gold color due to oxidization.
Ferruginous springs can be found in places such as Noboribetsu Onsen (Hokkaido)、Nagaragawa Onsen (Gifu), Yoshino Onsen (Nara), and Unzen Onsen (Nagasaki).

※Picture below is of Unzen Onsen (Nagasaki)

Types of Springs That Are Effective For Diabetes

Sulfur springs

Sulfur springs are said to cover a wide number of ailments, from lifestyle diseases such as diabetes, to other ailments such as chronic skin conditions and chronic gynecological diseases. Due to the high sulfur content, this type of onsen might smell like rotten eggs. It might be good to keep in mind that you should remove your accessories before entering a sulfur spring, as metals such as iron, bronze, and tin get oxidized by the spring water and turn black.
Sulfur springs can be found in places such as Takayu Onsen (Fukushima), Nikko Yumoto Onsen (Tochigi), Manza Onsen (Gunma), and Tsukioka Onsen (Niigata).

※Picture below is of Manza Onsen (Gunma)

Types of Springs That Are Effective For Skin Conditions

For skin diseases, acidic springs. For chronic skin diseases, chloride springs, sulfate springs, and radium springs.

While many different types of springs are said to be good for skin conditions, acidic springs are famed to have the best effect. The acidic nature of the spring water gives it disinfectant properties, which is why it is believed to be good for skin conditions. If you have sensitive skin, don't forget to take a shower after you have taken a dip in this type of onsen!
Acidic springs can be found in places such as Sukayu Onsen (Aomori), Zao Onsen (Yamagata), Kusatsu Onsen (Gunma), and Tateshina Onsen (Nagano).

※Picture below is of Kusatsu Onsen (Gunma)

Types of Onsen That Are Effective For Gout and Other General Illnesses

Radium springs

A special characteristic of barium springs is that it contains trace amounts of radioactive materials such as radium and radon. Believed to help in improving blood circulation and kidney functions, radium springs are effective for gout. Radium springs are also believed to be a panacea of sorts, as they are effective on a wide number of ailments.
Radium springs can be found in places such as Karurusu Onsen (Hokkaido), Geto Onsen (Iwate), Yunohana Onsen (Kyoto), and Misasa Onsen (Tottori).

※Picture below is of Misasa Onsen (Tottori)

Types of Onsen That Are Effective For High Cholesterol (For Drinking Only)

Iodide ion springs

Spring water containing more than 10mg of iodide ion per kilogram is defined as an iodide ion spring. While bathing in an iodide ion onsen has the general health benefits of other onsen, drinking from an iodide ion onsen can have good effects on patients with high cholesterol.
Iodide ion springs can be found in places such as Araya Onsen (Akita), Ogata Onsen (Akita), Otemachi Onsen (Tokyo), and Shirako Onsen (Chiba).

Did this help you know a little more about the different types of onsen? While these are the types and effects of onsen, the effectiveness and results may vary according to the individual, so it is best to take this as a guideline and explore and find the onsen that best suits your tastes!

*Please note that the information in this article is from the time of writing or publication and may differ from the latest information.

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