Taking extra fluids by mouth is the obvious treatment for dehydration and the drinking of water or other liquids is recommended.
A solution consisting of half a teaspoon of salt and eight teaspoons of sugar in a litre of previously boiled water is easily made and suitable for mild cases of dehydration. Rehydration salts in packets are also available.
If the person is unconsciousness or unable to drink, fluids can be administered via a tube inserted into the stomach.
If vomiting is constant and the situation more serious, intravenous rehydration may be necessary. Electrolytes (sodium and potassium) are also lost when someone has become dehydrated and acid-base balance is disturbed. These imbalances also need to be corrected.
In the case of sports people taking part in strenuous sporting activities, rehydration should be a priority. Many balanced solutions containing the correct amounts of carbohydrate and electrolytes suitable for athletes are available commercially.