Safety During Hot Spring Bathing | Heat Stroke, Heat Shock & Soaking Time

Recommended Water Temperature & Soak Duration

Japan's Ministry of the Environment recommends keeping bath water at 41 °C or below. High-temperature baths (42 °C+) stimulate the sympathetic nervous system, raising blood pressure and stressing the heart. Limit each soak to 15 minutes, and take rest breaks between rounds.

Signs of Overheating / Heat Stroke

• Flushed or very red faceThis is a visible sign that your body is trying to cool itself down by increasing blood flow to the skin. While some redness is normal, intense flushing can indicate that your body temperature is rising too quickly, putting a strain on your circulatory system.
• Dizziness or light-headednessHot water dilates your blood vessels, which can cause a temporary drop in blood pressure. This may reduce blood flow to your brain, leading to feelings of dizziness and increasing the risk of fainting.
• NauseaFeeling sick to your stomach is a key symptom of your body becoming overheated. This is a sign that the heat is stressing your system, and you should exit the bath immediately to cool down.
• Rapid heartbeat (palpitations)High temperatures make your heart work harder to pump blood to the skin for cooling. This sensation of a racing heart indicates increased strain on your cardiovascular system, a risk highlighted in bathing guidelines.

1. 1

   Exit the bath immediately at the first sign

   Do not tough it out. Staying in while overheating risks loss of consciousness.

2. 2

   Lie down in a cool area

   Move to the changing room or rest area and lie flat to stabilise blood circulation.

3. 3

   Rehydrate

   Drink room-temperature water slowly to replace lost fluids and electrolytes.

4. 4

   Seek medical help if symptoms persist

   If you do not feel better within 10–15 minutes, notify facility staff and call emergency services if necessary.

Advice for Older Adults & Those with Medical Conditions

Older adults and those with hypertension, heart disease, or diabetes should consult their doctor before bathing. Avoid bathing alone — choose facilities with attendant supervision.