Heat exhaustion is a milder form of heat-related illness that can develop after several days of exposure to high temperatures and inadequate or unbalanced replacement of fluids. Its signs and symptoms include heavy sweating, paleness, muscle cramps, tiredness, weakness, dizziness, headache, nausea or vomiting, and fainting. In heat exhaustion, the body’s temperature is usually normal.
Heat stroke is a more serious form of heat-related illness that can occur if your body temperature rises to 104 F (40 C) or higher. Heat stroke can cause damage to your brain and other internal organs. Its signs and symptoms include high body temperature, hot, dry skin or profuse sweating, rapid pulse, difficulty breathing, confusion, loss of consciousness, and seizures.