Taught by a Traditional Chinese Medicine Pharmacist: The 2 Types of Indoor Heatstroke in the Elderly and Infants, and How to Properly Treat Them

Introduction

I received this question during a TikTok Live session.

"Why do elderly people and infants get heatstroke indoors on cloudy days?"

When we think of heatstroke, we often imagine it happening during outdoor work or exercise under the blazing sun. However, the elderly and infants can suffer from heatstroke even on cloudy days or while indoors. From the perspective of Traditional Chinese Medicine, there are two types of heatstroke, and the treatment methods differ for each.

Conclusion

There are two types of heatstroke: dry sauna type and steam sauna type.

If you mistake the type, the treatment method can have the opposite effect. It is important to observe the symptoms carefully and provide the correct treatment.

Reason

The difference between the two types

Dry sauna type is heatstroke that occurs under the blazing sun or in high-temperature outdoor environments. Heat enters from outside the body, causing body temperature to rise rapidly. The basic treatment is to move the person to the shade, cool the body, and provide hydration.

Steam sauna type is heatstroke that occurs indoors or on cloudy days. Even if the temperature is not very high, heat becomes trapped inside the body due to high humidity and poor ventilation. This is the type most common in the elderly and infants.

Why is it common in the elderly and infants?

The elderly have reduced thermoregulatory function. They are less sensitive to heat and their ability to sweat is weakened, so they may not notice that heat is building up inside their bodies.

Infants have immature thermoregulatory function. Because their bodies are small, their body temperature rises easily relative to their body surface area, making them susceptible to environmental influences.

In Traditional Chinese Medicine, heat generated inside the body by food is called "internal heat." If stomach acid is diluted by excessive water intake, indigestion occurs, which generates heat within the body.

On rainy or cloudy days, humidity is high, making it difficult to sweat. The combination of internal heat and swelling on the skin's surface causes heat to become trapped inside the body. This is the mechanism behind heatstroke that occurs on cloudy days or indoors.

From a Western medical perspective, in high-humidity environments, sweat does not evaporate easily, which hinders the dissipation of body heat. The elderly and infants, who have weak thermoregulatory functions, are particularly susceptible to this effect.

Difficulty in noticing symptoms

Symptoms of the steam sauna type are more likely to appear from the evening until bedtime.

• Lethargy

• Feeling heavy in the body

• Having a slight fever

At first glance, it is difficult to distinguish from fatigue or the onset of a cold, and it can worsen without being noticed. If you experience a slight fever starting in the evening during this season, consider it a sign that heat is trapped inside your body.

Correct way to handle the steam sauna type

It is important not to cool the body down rapidly, but to gently release the heat and moisture trapped inside the body.

Soak slowly in a lukewarm bath (about 38–39 degrees Celsius) to induce a gentle sweat. This helps release heat and excess moisture from the body along with the sweat. Afterward, replenish lost fluids and electrolytes with an oral rehydration solution or similar.

Medicinal food recipe

Homemade oral rehydration solution

Instead of store-bought oral rehydration solutions, you can easily make one with ingredients you have at home.

Ingredients (for 1 person)

• Water 500ml

• Lemon juice 1 tablespoon

• Salt a pinch (approx. 1g)

• Brown sugar or cane sugar 1 teaspoon

Instructions

1. Add salt and brown sugar to the water and mix well.

2. Add lemon juice and mix further.

3. Drink little by little frequently.

Medicinal food point

• Lemon: Cools excess body heat and replenishes body fluids. It regulates the flow of Qi and is also useful for fatigue recovery.

• Salt: Replenishes minerals necessary for the body. It helps with water absorption and balances body fluids.

• Brown sugar/Cane sugar: Less refined than white sugar and rich in minerals. It replenishes Qi and provides energy to the body. Because it is less taxing on the body than white sugar, brown sugar or cane sugar is chosen in medicinal cooking.

Summary

• There are two types of heatstroke: the dry sauna type and the steam sauna type.

• The steam sauna type is common in the elderly and infants. Lethargy and a slight fever starting in the evening are signs.

• The treatment is to have them sweat gently in a lukewarm bath and replenish fluids with a homemade oral rehydration solution.

It is not the illness that is scary, but the lack of knowledge. By knowing the type of heatstroke, you can take the correct action. To protect your precious family, please start being aware of this from today.

Course Information

The 6-month Traditional Chinese Medicine Medicinal Cooking Technique Introductory Course will start on the second Monday of September 2026.

This is an introductory course that even beginners can learn with peace of mind. You will spend 6 months carefully learning the basics of medicinal cooking that are easy to incorporate into your daily meals.

• Course format: Zoom/Archive attendance

• Time: 20:00–21:00

• Tuition fee: 54,000 yen

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