The first thing people often mention about hot springs and the respiratory system is the comfort of breathing warm, moist air. In dry seasons, or when your nose or throat feels irritated, many people find it easier to breathe in the steamy atmosphere of a hot spring area. This is not unique to hot springs; it is a common sensation in humid environments.

In short, it is not appropriate to think that hot springs cure respiratory diseases themselves. The Ministry of the Environment lists mild asthma or emphysema as one of the general indications for bathing in all therapeutic hot springs, but this is a general description based on physical effects such as warming the body, not proof that a particular spring type has curative powers. It also assumes repeated use over a period of time. Individual responses vary widely.

This article explains what you can reasonably expect from hot spring steam, what you should not expect too much from, and what people with respiratory conditions such as asthma should keep in mind, based on the Ministry of the Environment’s standards.

This article provides general information and is not medical advice. If you have bronchitis, asthma, chronic obstructive pulmonary disease (COPD), or any other respiratory condition, or if you have shortness of breath or a persistent severe cough, do not push yourself. Consult your regular doctor. Hot spring steam is not treatment, and its effects or mechanisms are not necessarily established for each individual. If your doctor has restricted bathing, their instructions take priority.

Why steam can feel easier to breathe in

What people usually notice first in hot spring steam is that the dryness in their airways feels relieved. When you breathe humid air, the lining of your nose and throat is less likely to dry out, and breathing may feel easier. Some people also feel that warm steam helps mucus or nasal discharge come out more easily.

That said, this is temporary comfort caused by humidity and temperature, and it should be distinguished from any therapeutic effect of the spring minerals themselves. The same feeling can often be obtained from a humidifier or steam in a bathroom. The value of a hot spring area is not only the steam; it is also that the whole stay, including rest, sleep, and reduced stress, can help the body relax. Those environmental factors may also be part of why respiratory discomfort feels milder.

How to read the Ministry of the Environment’s indications

What is often called an indication for hot springs is a concept defined by the Ministry of the Environment under the Hot Springs Act. There are two kinds: general indications, which apply to all therapeutic hot springs, and spring-type indications, which are defined according to the mineral composition.

For the respiratory system, the general bathing indications include mild asthma or emphysema. The important point is that this is a general description based on physical factors such as warming effects, not a statement that a specific spring type, such as sulfur springs, is effective for respiratory disease. In fact, there are no respiratory-specific items in the spring-type indications.

In addition, indications are meant to be considered with repeated use over a certain period of time, such as a spa-style stay, and do not promise results from a single bath. Because symptoms and body types vary greatly, it is best to avoid saying that hot springs cure asthma. A broader classification of spring types is covered in Hot Spring Types Guide for Beginners.

Sulfur springs and hydrogen sulfide can be irritating instead

One of the most misunderstood cases in relation to the respiratory system is sulfur springs. People sometimes say that the sulfur smell is good for the throat, but hydrogen sulfide, the gas responsible for that smell, can irritate the eyes and airways even at low concentrations. While some people find it pleasant, others may cough or feel uncomfortable because of the irritation.

Safety is even more important. Hydrogen sulfide is heavier than air and tends to accumulate in poorly ventilated indoor areas or low-lying places such as depressions. At high concentrations it strongly irritates the respiratory system, and at even higher concentrations it can paralyze the respiratory center and become life-threatening. Regular commercial bath facilities are managed with ventilation and other safety measures, so there is no need to worry excessively, but you should always obey warning signs and no-entry notices around spring sources and fumarolic areas. More detail on sulfur springs and hydrogen sulfide is covered in The Smell and Color of Sulfur Springs.

It is also not appropriate to call the act of deeply inhaling steam or mist a form of treatment. Treat hot spring steam only as a source of supplementary comfort, and rather than trying to inhale it on purpose with deep breaths, it is safer to simply breathe naturally and observe how you feel.

Cautions for people with asthma or other respiratory diseases

People with asthma, a persistent severe cough, or shortness of breath may actually feel worse in hot, humid environments. Some people suit hot spring steam well, while others may find the heat or hydrogen sulfide irritating, and reactions vary greatly from person to person.

There are also views saying that it has not been confirmed that people with asthma are especially likely to trigger attacks at low concentrations of hydrogen sulfide. However, the fact that it is an irritating gas and that a hot bath environment can burden the respiratory system does not change. If you are prone to attacks or use inhalers, do not take long steam baths on your own judgment. If you feel short of breath, palpitations, or overheating, leave immediately. If your respiratory symptoms are severe, medical evaluation should come before visiting a hot spring. For general bathing safety, refer to Precautions Before Entering a Hot Spring.

If you try it, keep it within a reasonable range

If you want to enjoy a hot spring steam environment, start with a short time. Do not stay too long in places that are too hot, and check ventilation in enclosed bathing areas. For general guidance on bathing time and frequency, see How Long and How Often to Use a Hot Spring.

Hydration is just as important as bathing. In a steamy environment, you may sweat more than you realize and tire yourself out. If you start feeling unwell, prioritize your condition over enjoying the minerals, and do not forget to rest in a cool place.

FAQ

Does bathing in a hot spring cure asthma?

No, it cannot be said to cure it. The Ministry of the Environment lists mild asthma or emphysema as a general bathing indication, but this is a general description based on warming effects and assumes repeated use over time. Effects and mechanisms vary widely from person to person, so if your symptoms are severe, consult a doctor.

Are sulfur springs good for the respiratory system?

You cannot say that sulfur springs are good for the respiratory system simply because they are sulfur springs. There are no respiratory-specific items in the spring-type indications, and hydrogen sulfide, the gas behind the sulfur smell, can irritate the airways even at low concentrations. Some people find it pleasant, while others cough because of the irritation.

Does deeply inhaling the steam make it more effective?

It is not appropriate to think of intentionally taking deep breaths as treatment. In environments that contain hydrogen sulfide, it can be irritating. Breathe naturally, see how you feel, and leave the area if you become short of breath.

Can I go to a hot spring if I have asthma?

It may not suit you in hot, humid environments. People who use inhalers or are prone to attacks should avoid long steam baths, and if you are worried, consult your doctor in advance. If your doctor has placed bathing restrictions on you, those instructions take priority.

Can I get the same effect from a home humidifier?

You can get a similar level of comfort. The relief from dryness comes from humidity and temperature, so a humidifier or bathroom steam may also make your throat and nose feel easier. The unique value of a hot spring area lies not only in the steam but in the entire stay, including rest.

Conclusion

A hot spring steam environment can make dry airways feel easier and may relieve discomfort in the nose and throat. However, this is only temporary comfort caused by humidity and temperature, not a treatment for respiratory disease. The Ministry of the Environment lists mild asthma or emphysema as a general bathing indication, but this is a general note based on warming effects, not a spring-type benefit, and it assumes repeated use while individual responses vary greatly.

Because hydrogen sulfide in sulfur springs can irritate the airways even at low concentrations, it is a mistake to think simply that hot springs are good for the respiratory system. People with asthma or other respiratory diseases may actually feel worse in hot, humid environments, and if symptoms are severe, medical care should come first. It is best to enjoy hot spring steam as a supplementary comfort, within reasonable limits.

Sources

• Ministry of the Environment: Guideline for Mineral Spring Analysis Methods (Revised in 2014)
• Ministry of the Environment: Contraindications and Precautions for Bathing or Drinking Based on Article 18, Paragraph 1 of the Hot Springs Act
• Ministry of the Environment: Guide to Safe and Secure Hot Spring Use
• International Volcanic Health Hazard Network (IVHHN): Volcanic gases: hydrogen sulfide (H2S)