what are the causes of a dry mouth all the time?
 Dry mouth can be a result of nerve damage to the head and neck area from an injury or surgery. 2 Dehydration. 3 Conditions that lead to dehydration, such as fever, excessive sweating, vomiting, diarrhea, blood loss, and burns can cause dry mouth. 4 Surgical removal of the salivary glands. 5 Lifestyle. 