Heavy sweating is one of the first signs of heat exhaustion, which, if not treated, can progress into the more serious heat stroke.
Kids who have heat exhaustion may have paleness in their skin -- it is especially evident on their face. Skin that is cool and moist also is another warning sign.
Muscle cramps can signal the onset of heat exhaustion. Cramps can occur when people lose too much fluid through sweating, especially when the weather is warm.
Kids who have heat exhaustion often complain about feeling tired.
Dehydration that is associated with heat exhaustion can cause dizziness. Kids also may complain about having a headache.
Nausea and vomiting
Kids who have heat exhaustion may complain about nausea that comes on rapidly. If the nausea progresses, the child may vomit.
Clear urine is a sign of adequate hydration, while dark urine is a sign that the body is not properly hydrated. Dehydration, which hinders the ability of the body to maintain its normal temperature, is considered one of the causes of heat exhaustion.
Pulse and breathing
A child with heat exhaustion will have a fast, but weak, pulse, along with fast and shallow breathing.
One of the most common reasons people faint is an increased or decreased heart rate. Since people with heat exhaustion often have an unusually high heart rate, fainting is a sign that the condition has set in.