The number of patients suffering from heatstroke, the most fatal heat-related illness, has surged more than three times over the past five years.
According to the Health Insurance Review and Assessment Service, heatstroke patients increased by 208.4% from 1,073 in 2020 to 5,529 last year.
Over the same period, the total number of hospital visit days for heat-related illness patients rose by 163.6% from 4,068 to 10,725 days, and the total medical care benefit costs surged by 277.3% from 1.07 billion KRW to 4.04 billion KRW.
Heatstroke is classified as a severe condition among heat-related illnesses, which are acute diseases caused by heat.
It involves core body temperature, the temperature of internal body organs, exceeding 40°C (104°F), accompanied by central nervous system dysfunction such as altered mental status, delirium, or seizures.
Sometimes, heatstroke can be diagnosed even if the core body temperature is below 40°C (104°F), in which case the most crucial sign for recognition is a change in consciousness.
Between 2011 and 2025, about 44% of heatstroke patients exhibited changes in consciousness (31.1% impaired consciousness, 11.6% loss of consciousness, and 1.4% death).
In contrast, more than 90% of patients with heat exhaustion, heat cramps, and heat syncope remained fully conscious.
Heatstroke can lead to death if prompt action is not taken.
Among the 267 deaths recorded from 2011 to 2025 through the Korea Disease Control and Prevention Agency's emergency department surveillance system for heat-related illnesses, 95.8%, or 256 people, died due to heatstroke.
During this period, heatstroke patients accounted for 21.6% of all heat-related illness patients, and the mortality rate was high at 4.4%.
This is significantly higher than the mortality rate of heat exhaustion (0.04%), which is also a heat-related illness.
Heatstroke begins with mild symptoms initially, but can rapidly deteriorate depending on the person and the situation.
The first warning sign of heatstroke is excessive fatigue.
Patients tire more easily than usual, lose energy, and struggle with simple activities; taking appropriate rest and replenishing fluids at this stage can prevent the condition from worsening.
Headaches and dizziness are also important early symptoms.
Patients may complain that their "head feels heavy," they are "dizzy," or their "vision is blurred," and they may lose their sense of balance and stagger.
As body temperature subsequently rises in earnest, the skin becomes hot and red, and paradoxically, very little sweating occurs.
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