Does Your Workforce Know the Signs and Symptoms of Heat Illness?

June 1, 2023

Symptoms of heat illness can vary from person to person, presenting at different times and in different ways. It’s critical for employees and supervisors to know the many signs of heat illness and understand their health implications; if left untreated, they can cause lasting damage.

The most common symptoms – headache, nausea, vomiting and cramps – can indicate both the most and least severe forms of heat illness, making it difficult to distinguish between them. Ensure your teams are aware of the following heat illnesses and their associated symptoms:

Heatstroke – the most severe form of heat illness:

  • Throbbing headache
  • Dizziness
  • Nausea or vomiting
  • Confusion or staggering
  • Rapid pulse
  • Rapid, shallow breathing
  • Unconsciousness
  • Red, hot and dry skin with no sweat
  • Body temperature above 103 F

Heat exhaustion – a milder form of heatstroke:

  • Headache
  • Dizziness
  • Nausea, vomiting or diarrhea
  • Confusion
  • Rapid pulse
  • Fatigue
  • Heavy sweating
  • Paleness
  • Muscle cramps

Heat cramps – muscle spasms that are:

  • Painful
  • Brief
  • Involuntary
  • The result of sweat reducing salt and fluids in the body


  • Red, painful skin
  • Blistering
  • Swelling
  • Fever

For information about heat illness prevention and response, download our heat illness prevention handout and heat exhaustion prevention program or view Cal/OSHA’s heat illness prevention page.

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