Heat Stroke
Everything about the causes, prevention, prognosis, and first aid in response to a sudden increase in body temperature.
Symptoms and Causes
Heat stroke occurs when body temperature rises uncontrollably due to a failure in the body’s thermoregulatory mechanisms (such as sweating or redistribution of blood flow). As a result of this thermal collapse, the function of the brain, nervous system, lungs, kidneys, liver, or muscles becomes compromised. It is the most severe form of heat-related illness.
It can occur as a result of excessive and prolonged external heat exposure or from performing intense physical exercise in hot, humid environments.
Heat stroke is a serious condition that, if not treated promptly, can lead to multiorgan failure and death.
Symptoms
The most characteristic symptoms of heat stroke include:
- Fever above 40°C (104°F).
- Dehydration.
- Changes in sweating patterns.
- Loss of coordination.
- Altered level of consciousness: disorientation, confusion, drowsiness.
- Headache that worsens as dehydration progresses.
- Muscle weakness that may hinder movement.
- Muscle cramps.
- Hot, dry, and flushed skin—signs that sweating mechanisms are not functioning properly.
- Nausea and vomiting.
- Dizziness.
- Blurred vision.
- Increased heart rate.
- Rapid breathing.
- Fainting.
- Seizures.
- Coma.
Causes
The causes that may trigger heat stroke can be divided into two categories:
- Environmental:
- Excessively high temperatures, above body temperature.
- High humidity.
- Prolonged exposure to extreme heat.
- Endogenous:
- High fever.
- Excessive physical exertion.
- Exercise in hot climates.
Risk Factors
The risk of suffering a heat stroke increases under the following conditions:
- Age: children and older adults have a lower thermoregulatory capacity.
- Prolonged exposure to sunlight.
- Obesity.
- Dehydration: not drinking enough water to replace the fluid lost through sweating.
- Alcohol or caffeine consumption: these affect the body’s ability to regulate temperature.
- Wearing non-breathable clothing.
- Taking certain medications, such as antihistamines, antidepressants, antihypertensives, or antipsychotics.
- Workers who must wear heavy protective clothing in hot environments (foundry workers, firefighters, military personnel, beekeepers).
- Professional athletes.
Complications
The complications of heat stroke are severe. The most significant include:
- Head injuries resulting from a fall due to dizziness or loss of consciousness.
- Irreversible damage to vital organs.
- Disability.
- Death.
Prevention
To prevent heat stroke, it is recommended to follow these tips:
- Avoid exposure to the sun between 12 p.m. and 4 p.m.
- Stay hydrated: drink between two and three liters of water a day. It is important to drink water before feeling thirsty.
- Wear loose, breathable clothing in hot weather.
- Avoid alcohol consumption, especially when temperatures are high.
- Ventilate indoor spaces and keep them cool.
- Drink water before, during, and after physical activity.
- Do not remain inside vehicles when temperatures are high.
- If possible, avoid strenuous activity during the hottest hours of the day in summer.
- Increase physical effort gradually to allow the body to acclimate to the heat.
Which Doctor Treats Heat Stroke?
Heat stroke is a medical emergency that is treated in emergency medicine and intensive care medicine.
Diagnosis
Heat stroke is usually diagnosed clinically. In most cases, evaluating the symptoms along with the activity performed prior to onset—particularly if it occurred in a hot and humid environment—is sufficient.
To confirm the diagnosis, the following tests may be performed:
- Temperature measurement.
- Blood test: checks for electrolyte imbalances and measures oxygen and carbon dioxide levels in the blood, as these may indicate that the organs are not receiving sufficient oxygen.
Treatment
Heat stroke is a medical emergency, and emergency services (112 in the European Union, Switzerland, Norway, and Liechtenstein) should be called immediately if it is suspected. While waiting for medical teams to arrive, the following first aid measures are recommended:
- Stay in a cool, shaded area.
- Elevate the torso to facilitate breathing.
- Lower body temperature: remove clothing, fan the person, or place cool wet cloths on the forehead or neck.
- Offer small sips of water if the person is conscious.
- If the person loses consciousness but continues to breathe, place them in the recovery position.
The first objective of emergency specialists—even before arriving at the medical center—is to lower the patient’s body temperature to approximately 38°C (100.4°F), as this significantly reduces mortality risk. The following methods may be used:
- Remove clothing.
- Apply cold or ice compresses.
- Submerge the patient in lukewarm water to avoid excessive contrast.
- Use cooling blankets.
- Administer cold intravenous fluids.
If the cooling process triggers shivering—a physiological response to increase body temperature—muscle relaxants may be administered to prevent it.
Once normal body temperature is restored, physicians assess the impact of the heat stroke on the body and treat each resulting condition accordingly.
The prognosis after heat stroke varies depending on the patient’s age, the maximum temperature reached, and the degree of damage to vital organs. In many cases, patients can recover fully without severe complications, but others may experience long-term sequelae, such as chronic heart or kidney disease and neurological impairment. When body temperature rises excessively or medical care is delayed, the risk of death is very high. The World Health Organization (WHO) estimates that 85% of people over 65 who suffer a heat stroke die as a result of the damage caused to their body.
