If it is a hot desert, the patient is likely to be both hyperthermic and dehydrated, and both require treatment.

Oral Rehydration Salts, either commercial or homemade using the WHO formula, is the ideal fluid for oral rehydration. Water is of course okay, too. Personally, I'd let the patient drink up to a liter initially at their own pace, followed by an additional liter per hour as needed. Plain water should be followed by small amounts of food whenever the patient can tolerate eating, mostly for the minerals like sodium. A little *heavily diluted* sports drink or fruit juice can accomplish much the same thing.

But these patients really don't need to be loaded up with sodium, potassium and other electrolytes; they are called "trace" minerals for a reason. Too much fluid too rapidly also will cause vomiting, which would only make things worse. Alcohol, soda, coffee and tea are diuretics and will also worsen dehydration. It should go without saying that these patients also require a medical follow-up ASAP, even if they appear fully recovered. Acute dehydration can lead to organ damage or failure, notably in the kidneys, and a host of other medical consequences.