Heat syncope or fainting is a mild form of heat illness that often results from physical exertion when it is hot. It occurs when your body, in an effort to cool itself, causes the blood vessels to dilate to such an extent that blood flow to the brain is reduced. Inadequate fluid replacement, which leads to dehydration, usually contributes greatly to this illness.


  • Faintness
  • Dizziness
  • Headache
  • Increased pulse rate
  • Restlessness
  • Nausea
  • Vomiting
  • Brief loss of consciousness


  • Lie or sit down in the shade or a cool area
  • Elevate the feet
  • Drink fluids containing salt
  • Refrain from vigorous activity