Onsen contraindications refer to illnesses or physical conditions for which bathing in an onsen, or drinking its water, is said to be best avoided. They are the opposite of “therapeutic indications,” which describe conditions for which use may be suitable. In short, contraindications summarize situations in which bathing may place extra strain on the body or increase risk. The Ministry of the Environment sets this framework under Japan’s Hot Springs Act, and it was revised in 2014 to reflect the latest medical knowledge. For that reason, it is safer to rely on the current framework rather than outdated information.

This article serves as a hub for understanding onsen contraindications correctly. It covers general bathing contraindications, cautions by spring type, the difference from therapeutic indications, how to read onsen analysis sheets and bathhouse notices, and where people with chronic conditions should seek advice. For a broader safety overview, including dangerous ways to bathe and heat shock, see Onsen Safety Tips.

This article provides general information and is not medical advice. Whether a condition counts as a contraindication depends on the illness and the individual. If you have a chronic condition, are pregnant, or are feeling unwell, do not push yourself; consult your regular doctor if needed. If a physician has restricted bathing, that instruction takes priority. Also follow facility notices and staff guidance.

What Are Contraindications? How They Differ from Therapeutic Indications

When people talk about hot springs, both “benefits” and “conditions to avoid” belong to the same official framework set by the Ministry of the Environment. The former are therapeutic indications—symptoms or conditions for which use is considered suitable. The latter are contraindications—illnesses or conditions for which use should be avoided. They are two sides of the same coin, and not confusing them is the starting point for understanding onsen safely.

The relationship between therapeutic indications and contraindications can be summarized as follows.

Therapeutic indications do not guarantee a benefit. They are based on repeated use over a certain period. A detailed explanation of how to read them and how to think about them scientifically is covered in The Science of Onsen Health Benefits. Contraindications, by contrast, are a safety guideline that says, “Avoid this if you are in this condition.” Remember that therapeutic indications and contraindications are not the same thing. Even if a hot spring has benefits, that does not mean everyone should enter it regardless of their condition.

There are two kinds of contraindications: general contraindications, which apply to all hot springs, and spring-type-specific contraindications, which vary by spring quality. First, let’s look at the general ones.

General Bathing Contraindications in Onsen (Ministry of the Environment, 2014 Revision)

Under Japan’s Hot Springs Act, the Ministry of the Environment provides the framework of contraindications that onsen facilities must display. The 2014 revision of the “Guidelines for the Analysis of Mineral Springs” updated the contents in line with current medical knowledge and removed items with little scientific basis. The table below summarizes the conditions commonly listed as general bathing contraindications and why they are considered reasons to avoid bathing. This is a general explanation only; individual decisions should be left to a doctor.

The main idea is simple: avoid acute, unstable conditions and situations in which the whole body is severely weakened. Fever is especially important because bathing can raise body temperature further and make symptoms worse. People with serious heart or lung disease may find that heat and water pressure put extra strain on blood pressure and heart rate. These points are also covered in Onsen Safety Tips, which explains who should generally avoid bathing, so be sure to review it along with safe bathing practices.

The 2014 Revision Removed Pregnancy from General Contraindications

In the past, pregnancy was included among the general contraindications. In the 2014 revision, however, it was removed. The reason was that no scientific evidence had been confirmed linking bathing in simple hot springs to miscarriage or premature birth. Because older notices and sources may still reflect the previous standard, it is important to understand the current framework accurately.

That said, being removed from the list does not mean there are no limits at all. You still need to be careful about feeling faint, dehydration, and slips or falls in the bath area. Judgments also vary depending on your condition and stage of pregnancy. For more on onsen during pregnancy, see Pregnancy and Onsen, and if you have concerns, prioritize consulting your obstetrician.

Contraindications to Watch by Spring Type

In addition to the general contraindications, some spring types are said to be unsuitable for certain people. The basic idea is that stronger springs can feel more burdensome for people with sensitive skin or mucous membranes, as well as for older adults with dry skin. The following are only general tendencies, not absolute rules.

If a strongly stimulating spring stings, turns the skin red, or causes itching, do not force yourself to stay in. Get out early and rinse with fresh water. Onsen use for people with skin conditions such as atopic dermatitis or psoriasis is covered in Atopic Dermatitis, Psoriasis, and Onsen. The next section explains how to check spring names and ingredients.

Contraindications Are Listed on Notices and Analysis Sheets

Contraindications and therapeutic indications are not something you judge only from memory. Onsen facilities are required to display an onsen analysis sheet and a summary of it, and those documents list the spring type, therapeutic indications, contraindications, and bathing precautions. They are often posted in the changing room or at the entrance to the bath area.

When checking the notice, look first at the spring type, second at the therapeutic indications and contraindications, and third at usage details such as whether the water is diluted, heated, recirculated and filtered, or mixed with bath additives. Reading this information gives you the material you need to decide whether bathing is appropriate for your condition and medical history. For a detailed explanation of the items on an onsen analysis sheet and how to interpret them, see How to Read an Onsen Analysis Sheet. If the posted contraindications differ from your doctor’s instructions, follow the doctor’s instructions.

Do Not Self-Judge If You Have a Chronic Condition

The contraindication framework is a general guideline, not an answer for every individual medical condition. Even with the same diagnosis, bathing may or may not be appropriate depending on symptom severity and treatment stage. If you have a chronic condition, do not assume that “it’s fine because it’s not listed as a contraindication.” Consult your doctor first, and use lukewarm water and short bathing times as a basic rule.

We have separate articles covering the main chronic conditions and their specific cautions.

• If you have high blood pressure: High Blood Pressure and Onsen
• If you have diabetes: Diabetes and Onsen
• If you have heart disease: Heart Disease and Onsen
• If you have skin conditions such as atopic dermatitis or psoriasis: Atopic Dermatitis, Psoriasis, and Onsen
• If you are recovering from surgery or have wounds: After Surgery, Wounds, and Onsen

For a general safety overview to help you avoid dangerous bathing practices and heat shock, see Onsen Safety Tips. For a scientific look at therapeutic benefits, see The Science of Onsen Health Benefits. Separating contraindications, which describe conditions to avoid, from therapeutic indications, which describe conditions thought to be suitable, is the foundation of safe onsen use. If you are unsure, follow your doctor and the guidance at the facility.

Frequently Asked Questions

What Are Onsen Contraindications?

They are illnesses or physical conditions for which bathing in or drinking an onsen is said to be best avoided. The Ministry of the Environment sets the framework under Japan’s Hot Springs Act, and it includes general contraindications that apply to all hot springs as well as spring-type-specific contraindications. They are the opposite of therapeutic indications, which describe beneficial uses.

Can I Go to an Onsen When I Have a Fever?

No. Please avoid it. Fever and other active phases of illness are included in the general contraindications. Bathing may raise your body temperature further and worsen symptoms or drain your energy, so the basic rule is to use the hot spring after you have recovered.

Can I Use an Onsen During Pregnancy?

The Ministry of the Environment removed pregnancy from the general contraindications in the 2014 revision because no scientific evidence had been confirmed linking bathing in simple hot springs to miscarriage or premature birth. However, that does not mean there are no restrictions. You still need to be careful about feeling faint, dehydration, and falls. For details, see Pregnancy and Onsen, and if you are concerned, consult your obstetrician.

If I Have a Chronic Condition, Am I Not Allowed to Use an Onsen?

Not necessarily. However, contraindications are only general guidelines, and even with the same diagnosis, the decision can change depending on symptoms and treatment stage. Do not self-diagnose; consult your doctor, and use lukewarm water and short bathing times as a rule. Condition-specific cautions are covered in High Blood Pressure and Onsen, Diabetes and Onsen, Heart Disease and Onsen, and others.

Where Can I Check Contraindications?

Onsen facilities post an onsen analysis sheet and summary in the changing room or at the entrance to the bath area. These list the spring type, therapeutic indications, contraindications, and bathing precautions. For how to read them, see How to Read an Onsen Analysis Sheet. If the notice and your doctor’s instructions differ, follow your doctor’s instructions.

Conclusion

Onsen contraindications are the Ministry of the Environment’s official framework that summarizes illnesses and physical conditions for which bathing or drinking should be avoided. General bathing contraindications include the active phase of illness, especially fever; active tuberculosis; advanced malignant tumors, severe anemia, and other states of marked weakness; serious heart, lung, or kidney disease; gastrointestinal bleeding or visible bleeding; and acute exacerbation of chronic disease. Pregnancy was removed from the general contraindications in the 2014 revision, but that does not mean there are no limits.

Contraindications are a different concept from therapeutic indications, and they can be checked on onsen analysis sheets and bathhouse notices. For strongly stimulating spring types such as acidic or sulfur springs, people with sensitive or dry skin should be cautious. In all cases, no one can be said to be “absolutely safe,” so if you have a chronic condition, consult your doctor rather than relying on your own judgment, and follow the posted guidance and instructions from staff.

Sources

• Ministry of the Environment, “Guidelines for the Analysis of Mineral Springs (2014 Revision)”
• Ministry of the Environment, “Protection and Use of Hot Springs” (Therapeutic indications, contraindications, and more)
• Ministry of the Environment, “Definition and Classification of Therapeutic Hot Springs”