What Are Signs of Heat Stroke?

Heat stroke happens in hot conditions when the body's cooling system fails. Heat stroke, characterized by confusion, panting, hot skin, vomiting and other signs, is a medical emergency.

Heat stroke (also called sun stroke) is a life-threatening medical condition that occurs when the body's cooling system stops working and the body’s core temperature increases to a point at which brain damage or damage to internal organs can occur (105° F [40.5° C] or greater).

Older people and people who have health problems can be more prone to developing heat stroke, even without exercising in the heat.

Heat stroke is a medical emergency that can lead to death if it is not treated promptly.

11 Symptoms and signs of heat stroke include:

1. Body temperature of 104°F (40°C) or higher
2. Brain symptoms 
   • Confusion or problems thinking clearly
   • Seeing or hearing things that aren't real (hallucinations)
   • Trouble walking
   • Seizures
   • Fainting
   • Coma
3. Fast breathing (hyperventilation)
4. Fast heartbeat
5. Skin redness (flushing) and warmth or heat
6. Dry skin
7. Vomiting or diarrhea
8. Muscle cramps or weakness
9. Headaches
10. Absence of sweating due to dehydration
11. Changes in blood pressure (maybe high or low)

Heat stroke occurs when heat exhaustion – a condition that precedes heat stroke -- is not treated right away. Heat stroke is a medical emergency that can lead to death if it is not treated promptly.

Heat stroke frequently occurs when people exercise, work, or play in very hot and humid weather. Inadequate fluid intake, wearing too many layers of clothing, and alcohol consumption can also contribute to developing heat stroke. 

Heat stroke can also occur without activity from prolonged exposure to very hot and humid environments. This more commonly occurs in the elderly or people who have an underlying medical condition. 

Risk factors that can make people more likely to develop heat stroke include: 

• Age (toddlers and young children, the elderly) 
• Diuretic use 
• Low potassium levels (hypokalemia) 
• Alcohol use
• Inadequate heat acclimatization
• Low fitness levels
• Being overweight or obese
• Lack of sleep
• Stomach illness

Heat stroke is a medical emergency. Seek medical care at a hospital’s emergency department right away if heat stroke is suspected or if the person has the following symptoms: 

• Inability to keep fluids down (vomiting) 
• Deterioration of mental status (confusion or delirium)
• Shortness of breath
• Chest pain
• Abdominal pain 

Heat stroke is diagnosed with a physical exam and a temperature reading. Other tests that may be indicated to determine if the heat stroke has affected other organs in in the body may include:

• Blood tests
• Urine tests
• Chest X-ray
• Electrocardiogram (ECG) of the heart

Heat stroke is a medical emergency. There is no home treatment for heat stroke. 

Heat stroke must be treated medically and treatment involves cooling the body as soon as possible. Methods used to reduce a person’s body temperature may include: 

• Immersion techniques, such as placing the patient into an ice bath
• Evaporative techniques, such as using a fan to blow air on wet skin 
• Invasive cooling techniques, such as chilled intravenous (IV) fluids
• Additionally, ice packs applied to the body or cooling blankets may be used as adjuncts to the methods above

Treatment continues until the patient’s core body temperature is 101.3°-102.2° F (38.5°-39° C). 

Patients may be admitted to the hospital for observation and additional testing if needed. 

Heat stroke can affect almost every organ system and can lead to complications such as:

• Brain damage
  • Cerebellar deficits
  • Dementia
  • Paralysis on one side of the body (hemiplegia)
  • Weakness of arms and legs (quadriparesis)
  • Personality changes
• Muscle damage
  • Breakdown of muscle tissue (rhabdomyolysis)
  • Compartment syndrome
• Acute kidney injury 
• Acute liver failure 
• Disseminated intravascular coagulation (DIC) (rare)
• Acute respiratory distress syndrome (ARDS)

When it is hot or humid, steps to prevent heat stroke include:

• Don’t exercise outdoors
• If you exercise outdoors, keep activity levels low and take frequent breaks
• Drink enough fluids, such as water or sports drinks
• Avoid drinking large amounts in a short time, which can be harmful
• Exercise early in the day, before it gets too hot 
• Wear loose, lightweight clothing

Pay attention to symptoms of heat cramps or heat exhaustion and stop activity and cool down right away so symptoms do not progress to heat stroke, which is a medical emergency. 

• Heat cramps cause painful muscle cramps
• Heat exhaustion can cause headaches, dizziness, nausea, vomiting, thirst, or tiredness

To cool down quickly:

• Move into the shade or go into an air-conditioned building or car
• Take a cool shower or bath
• Drink water or a sports drink; avoid caffeine and alcohol
• Remove excess clothing
• Spray yourself with cool water and sit in front of a fan
• Place a cold pack or cool compress on the neck, armpits, or groin