Heat exhaustion is a more severe condition than heat cramps. It often affects athletes, fire construction workers, and workers, as well as those who heavy clothing in a hot, humid environment. Its signals include cool, moist, pale, or flushed skin, headache, nausea, dizziness, weakness, and exhaustion.

Heat stroke is the least common but most severe heat emergency. It most often occurs when people ignore the signals of heat exhaustion.
Heat stroke develops when the body systems are overwhelmed by heat and begin to stop functioning. Heat stroke is a serious medical emergency. The signals of heat stroke include red, hot, dry skin; changes in consciousness; rapid, weak pulse, and rapid, shallow breathing.

When you recognize heat-related illness in its early stages, you can usually reverse it. Get the victim out of the heat. Loosen any tight clothing and apply cool, wet cloths, such as towels or sheets.
If the victim is Conscious, give cool water to drink.
Do not let the Conscious victim drink too quickly. Give about one glass (4 ounces) of water every 15 minutes. Let the victim rest in a comfortable position, and watch carefully for changes in his or her condition. The victim should not resume normal activities the same day.

Refusing water, vomiting, and changes in consciousness mean that the victim's condition is getting worse. Call for an ambulance immediately if you have not already done so.