The most obvious first sign of heat exhaustion or dehydration is usually intense thirst and a desperation to drink. But it is important to be aware that this symptom may not always appear with certain people or situations, such as where water is not available so the person's sub conscience masks the sensation; or else in people suffering from some types of diabetes or kidney failure. Further symptoms of dangerous level of dehydration or heat exhaustion affecting somebody include:-
2. Lips very dry
3. Very dry tongue
4. Dizziness
5. Very confused
6. Heart rate and breathing rate up and noticeably very fast
7. Skin pale and very dry and loss of elasticity.
8. Very dark colored urine
9. Lethargy
10 Headaches
11 Cramps all over body.
These symptoms will usually soon lead to him or her going into a coma.

After dehydration has developed to possibly avoid need for hospitalization, the replacement of both lost fluids and when applicable of salt is absolutely vital. This will need to be done at greater rate than that which would be needed just to prevent dehyration before it has occurred. It may be necessary for fluids to be replaced intravenously if coma has occurred.

Usually people that are at most high risk is alcoholics, elderly and people taking medications that warn against being in the sun when taking those meds. All this information and a lot more on this subject can be found at www.webmd.com This is a very informative site.
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