There are many causes of dry mouth. Dry mouth most commonly occurs as a side effect of medications that cause decreased saliva production, including high blood pressure medications, antihistamines, antidepressants, diuretics, nonsteroidal anti-inflammatories, narcotics, and many others.
Liquid diet: The Liquid diet is the restriction of solid food intake, and replacement of solid food with liquids. In hospitals, liquid diets are prescribed by doctors for a number of reasons for patients who are unable to consume solid foods. Liquid diets may be prescribed following surgery or as a preparation for certain medical procedures.
Like the name suggests, liquid diets mean you're getting all, or at least most, of your calories from drinks. Some liquid diets are limited to fruit or vegetable juices, or shakes, that replace all of your meals, taken three or four times a day. You do some of these diets on your own. Others need medical supervision.