Symptoms - "Must Read"

When exposed to very hot temperatures you may suffer first from heat exhaustion, which manifests itself as one or several of the following :

If heat exhaustion is not treated effectively then the condition can progress to the potentially fatal heat stroke whose symptoms are one or several of the following :

In fit people and athletes sweating will probably be present during heat stroke if it is bought on by exercise / hard work. This is because the stroke may be due to heat generated inside the body by exercise, and not by dehydration.

In the case of dehydration induced heat stroke sweating is very unlikely to be present.

Extra information

The above is the normal way in which heat illnesses are described. Some medical authorities do not see a division in the symptoms in this way. The alternative view sees them as a whole set of symptoms which represent increasing severity of the condition. Any one or combination of them could indicate progression towards the most serious of the heat conditions ie heat stroke. This alternative is a much safer approach when away from medical support, since it prompts treatment and action based on the most serious possible situation. No significant harm would be done by treating a minor heat illness as a serious one. On the other hand someone could be at risk of death if treated for the minor heat exhaustion when the symptom was an indication of heat stroke.

To quote the American College of Sports Medicine

"Heat stroke is regarded as a medical emergency that might be fatal if not immediately diagnosed and properly treated.

Early diagnosis is of the utmost importance and time consuming investigation should be postponed until body temperature is corrected and the patient is evacuated to a nearby medical facility that is aware of such conditions."

The only certain way of checking if the heat illness is serious is to take the body's temperature with a rectal thermometer.

Mouth and Ear measurements have been affected by the external temperature and skin temperature, and have not indicated the temperature at the core of the body. Recent technical developments suggest that new ear thermometers will be capable of giving the correct body temperature. In the mean time :-

If you do not have immediate access to a rectal thermometer you will not know absolutely whether the symptoms arise from dangerous internal temperatures or a more minor condition. For this reason it is best to treat the symptoms as signs of heat stroke requiring vigorous field first aid.

The next best indication of heat illness is the person's mental condition, because the brain is the organ which is most sensitive to the body's internal temperature. Mild confusion is a concern, however major confusion, disruptive behaviour, and unconsciousness should be considerd as showing a life threatening condition.

Speed is vital since for heat stroke the mortality rate and organ damage are proportional to the length of time the body's core temperature has been too high. The sooner cooling is initiated the better.

The more rapidly treatment is given, the more likely a full recovery is to be made.

The sufferer should be cooled down as quickly as possible with whole body cooling, and then taken straight to hospital.

Heat stroke occurs when the body's temperature is at a level which causes damage to the body's tissues. This is at about 40.6 oC [ 105 oF ] in the conscious, and may be as high as 42-43 oC [ 107.6 - 109.4 oF ] in the unconscious.

As the heat effects progress there can be a breakdown in the body's ability to reduce its own temperature through sweating, ie sweating reduces or stops and body temperature can reach as much as 107F. In some cases people have been known to start shivering producing even more heat internally, because their body's heat control mechanism gets confused by the wrong messages from the cold nerve endings on the skin and their body "thinks" it is too cold!

If untreated it is possible that multiple organ failure occurs, such as the heart, lungs, kidney and brain. The sufferer can fall into shock and unconsciousness.

Factors giving even greater risk and danger :

Significance of symptoms

If you are in a hot environment, and you do not have immediate access to medical support and a cool environment then even the apparently milder heat exhaustion symptoms should be treated with urgent and vigorous first aid cooling because time is critical. The symptoms may be of heat stroke, however heat exhaustion can become heat stroke if vigorous cooling isn't initiated causing brain damage and/or death faster than you might imagine.

There is a more minor condition Heat Syncope - fainting - which happens without a rise in core body temperature, and probably results from there being insufficient blood to service the brain. Unfortunately it's symptoms can be very like some of those for heat exhaustion / stroke and without a rectal thermometer to check the patient's temperature it can be dangerous to assume that the condition is just fainting.

Inappropriate urination: If you should find you have gone to the lavatory several times during the night in a very hot climate, this is very unusual. You should get yourself checked, and avoid exercise until the salt situation is clear.