Heat stroke is the most serious form of heat injury and is considered a medical emergency. If you suspect that someone has heat stroke -- also known as sunstroke -- call 911 immediately and give first aid until paramedics arrive.

Heat stroke can kill or cause damage to the brain and other internal organs. Although heat stroke mainly affects people over age 50, it also takes a toll on healthy young athletes.

Heat stroke often occurs as a progression from milder heat-related illnesses such as heat cramps, heat syncope (fainting), and heat exhaustion. But it can strike even if you have no previous signs of heat injury.

Heat stroke results from prolonged exposure to high temperatures -- usually in combination with dehydration -- which leads to failure of the body's temperature control system. The medical definition of heat stroke is a core body temperature greater than 105 degrees Fahrenheit, with complications involving the central nervous system that occur after exposure to high temperatures. Other common symptoms include nausea, seizures, confusion, disorientation, and sometimes loss of consciousness or coma.


Symptoms of Heat Stroke
The hallmark symptom of heat stroke is a core body temperature above 105 degrees Fahrenheit. But fainting may be the first sign.

Other symptoms may include:

Throbbing headache
Dizziness and light-headedness
Lack of sweating despite the heat
Red, hot, and dry skin
Muscle weakness or cramps
Nausea and vomiting
Rapid heartbeat, which may be either strong or weak
Rapid, shallow breathing
Behavioral changes such as confusion, disorientation, or staggering
Seizures
Unconsciousness

Preventing Heat Stroke
When the heat index is high, it's best to stay in an air-conditioned environment. If you must go outdoors, you can prevent heat stroke by taking these steps:

Wear lightweight, light-colored, loose-fitting clothing, and a wide-brimmed hat.
Use a sunscreen with a sun protection factor (SPF) of 30 or more.
Drink extra fluids. To prevent dehydration, it's generally recommended to drink at least eight glasses of water, fruit juice, or vegetable juice per day. Because heat-related illness also can result from salt depletion, it may be advisable to substitute an electrolyte-rich sports drink for water during periods of extreme heat and humidity.
Take additional precautions when exercising or working outdoors.The general recommendation is to drink 24 ounces of fluid two hours before exercise, and consider adding another 8 ounces of water or sports drink right before exercise. During exercise, you should consume another 8 ounces of water every 20 minutes, even if you don't feel thirsty.
Reschedule or cancel outdoor activity. If possible, shift your time outdoors to the coolest times of the day, either early morning or after sunset.

Symptoms of heat stroke include flushed skin, rapid breathing, high body temperature etc. Heatstroke is a condition caused when your body overheats, which is often as a result of prolonged exposure to or an intense physical exertion in high temperatures. Click on the link below to read more.
http://www.gigihealth.com/symptoms-of-heat-stroke-what-causes-heat-stroke/