Oral care delivered by healthcare professionals should be guided by best available scientific evidence. Xerostomia (pronounced zeer oh stomia) is a rapidly growing problem in an aging U.S. population and a condition that has a variety of possible causes including the use of xerogenic medications, tobacco smoking, alcohol use (including alcohol-containing mouthrinses), the use of beverages that contain caffeine and certain chronic health conditions like Sjögren’s syndrome, head and neck cancer therapy, HIV-associated salivary gland disease, blood and marrow transplants, bulimia, diabetes, nutritional deficiencies in the elderly and mouth breathing. Clinical guidelines for oral treatment and dental caries prevention in patients with chronic xerostomia are complicated by new products and therapies and need to be assessed by dental teams on a regular basis. Interdisciplinary collaboration between the dental and medical community is important, particularly when treating individuals with complex chronic conditions that may induce chronic hyposalivation. Xerostomia is considered a subjective sensation of dry mouth by some individuals whereas chronic hyposalivation is defined by assessing salivary flow rate.