Symptoms of Heat Stroke
Heat stroke is a life-threatening emergency characterized by core body temperature ≥104°F (≥40°C) combined with central nervous system dysfunction, including altered mental status, delirium, convulsions, or coma. 1
Cardinal Diagnostic Features
The diagnosis requires two essential components:
- Severe hyperthermia: Core body temperature exceeding 104°F (40°C), though this threshold may occasionally be lower in some cases 1, 2
- Central nervous system abnormalities: This is the defining feature that distinguishes heat stroke from heat exhaustion and includes delirium, convulsions, altered mental status, or coma 1, 3
Neurological Manifestations
Heat stroke presents with profound neurological dysfunction that differentiates it from milder heat illness:
- Altered consciousness: Ranging from confusion and disorientation to profound coma 1, 3
- Combativeness and delirium: Patients may be agitated, combative, or exhibit bizarre behavior 3
- Seizures: Can occur acutely or develop days after initial presentation (status epilepticus has been reported) 4, 3
- Profound mental changes: Including inability to recognize surroundings or people 1
Associated Systemic Symptoms
Beyond the core diagnostic criteria, heat stroke commonly presents with:
- Cardiovascular collapse: Inability to maintain blood pressure and adequate cardiac output, potentially progressing to cardiac arrest 1, 2
- Gastrointestinal symptoms: Nausea and vomiting (though these are more prominent in heat exhaustion) 1
- Weakness and collapse: Inability to continue activity or maintain upright posture 5
Multi-Organ Dysfunction
Heat stroke triggers systemic inflammatory response syndrome leading to:
- Rhabdomyolysis: Muscle breakdown causing myoglobinuria and potential acute kidney injury 2, 4
- Hepatic injury: Liver damage and dysfunction 6
- Renal failure: Acute kidney injury requiring potential dialysis 6, 4
- Coagulopathy: Disseminated intravascular coagulation can develop 7
- Hematological abnormalities: Blood system dysfunction 6
Critical Distinction from Heat Exhaustion
Understanding the difference is essential for appropriate management:
- Heat exhaustion presents with weakness, dizziness, nausea, syncope, headache, and heavy sweating, but core temperature remains below 104°F (40°C) and no CNS dysfunction occurs 1, 5
- Heat stroke always involves CNS abnormalities (altered mental status, seizures, coma) with temperature ≥104°F 1
Common Pitfall
The most critical error is delaying treatment while waiting for temperature verification. If a patient exhibits moderate to severe CNS dysfunction after heat exposure or exertion, assume heat stroke and initiate immediate cooling—do not wait for rectal temperature confirmation 1. The American Academy of Pediatrics explicitly states that appropriate treatment should not be delayed if rectal temperature cannot be assessed in patients with clinical signs suggestive of severe heat stress 1.
When to Activate Emergency Services
Immediate emergency activation is required for: