Heat Exhaustion
This is due to excessive sweating in an atmosphere of high temperature when there is both fluid and salt depletion and the subject has not taken enough fluid or salt to make good the loss. Heat exhaustion may be of two types:

Heat exhaustion due to loss of salts (heat cramps):

This is characterized by weakness, headache, giddiness, nausea, vomiting, cramps in the legs and irritability. Gradually the BP falls and the patient becomes pale. The pulse becomes weak and quick and the patient collapses. Chloride and sodium levels and the urinary choloride levels are very low.

Andydrotic heat exhaustion:

This is seen in association with prickly heat. The patient feels extremely weak, becomes irritable and the BP is low.

A little effort may cause the patient to collapse. There may be localized sweating in the axilla, hands and forehead. This condition may lead to heat stroke.

Treatment:

Keep the patient in a cool environment. Water replacement may be done by giving adequate water to drink. Bryonia, Glonine china, Natrum mur and Avena sat are good homoeopathic medicines to use.