Heat stroke is a very serious condition, the most dangerous form of heat injury. Caused by the body overheating to an extreme temperature, it can cause serious, lasting damage and even be fatal if not treated immediately.
Also known as sun stroke, this condition is a type of heat exhaustion. You should always be on the lookout for signs of heat injury when spending time in high temperatures, especially when physical activity is taking place, whether play or exercise — it may be possible to prevent heat stroke from occurring by catching earlier signs of the heat exhaustion from which it progresses. A headache, as well as nausea that may or may not result in vomiting, are some of the earliest signs. Heat cramps in the abdomen and other muscles, as well as lethargy also indicate heat exhaustion is setting in; encourage someone with these symptoms to get out of the sun and heat for a rest. Fainting is a definite sign you should get out of the heat.
Dehydration is almost always involved in, and contributes to, heat stroke, so be on the lookout for it. Changes in sweat levels are one sign of this: if you’re not able to sweat quickly enough to cool yourself, it can lead to the overheating that causes heat stroke, so someone who is not sweating, and whose skin is hot and dry to the touch despite being in high heat may be at risk. Skin may also become clammy despite the lack of sweat, and will often become flushed and red. You may also experience dizziness and lightheadedness.
The heart is one of the organs that is most affected by, and at risk for damage from, sun stroke. Changes in heart rate and breathing are important indications: a rapid heartbeat, which may start out weak or become very strong is a dangerous symptom. Breathing also becomes rapid and shallow.
Changes in mental state, such as confusion, agitation, and disorientation, are serious signs of heat stroke; slurring words and staggering steps can indicate these. A seizure is obviously another serious symptom.
Heat stroke requires emergency medical attention, so if you suspect someone of having one, take first aid steps of removing them to a cool, shady area and attempting to cool them by applying ice or cold water — but call 911 immediately.