Heat stress can cause several conditions such as heat fatigue, heat rashes, heat cramps, heat collapse, heat exhaustion, and heat stroke. Heat stroke is the most serious condition and can be fatal if not treated promptly by moving the person to a cool place, removing excess clothing, fanning air over their body, and wetting their skin with cool water while calling for medical help. People should take steps to prevent heat illness by staying hydrated, limiting time outdoors during peak heat, and monitoring their body for signs of distress.