Parasympathomimetic drugs (saliva stimulants) such as pilocarpine may improve xerostomia symptoms and other problems associated with salivary gland dysfunction, but the evidence for treatment of radiation-induced xerostomia is limited. Both stimulants and substitutes relieve symptoms to some extent. Salivary stimulants are probably only useful in people with some remaining detectable salivary function. A systematic review compromising of 36 randomised controlled trials for the treatment of dry mouth found that there was no strong evidence to suggest that a specific topical therapy is effective. This review also states that topical therapies can be expected to provide only short-term effects, which are reversible. The review reported limited evidence that oxygenated glycerol triester spray was more effective than electrolyte sprays. Sugar free chewing gum increases saliva production but there is no strong evidence that it improves symptoms. Plus, there is no clear evidence to suggest whether chewing gum is more or less effective as a treatment. There is a suggestion that intraoral devices and integrated mouthcare systems may be effective in reducing symptoms, but there was a lack of strong evidence. A systematic review of the management of radiotherapy-induced xerostomia with parasympathomimetic drugs found that there was limited evidence to support the use of pilocarpine in the treatment of radiation-induced salivary gland dysfunction. It was suggested that, barring any contraindications, a trial of the drug be offered in the above group (at a dose of five mg three times per day to minimize side effects). Improvements can take up to twelve weeks.
However, polypharmacy is thought to be the major cause in this group, with no significant decreases in salivary flow rate being likely to occur through aging alone. Drug induced
Aside from physiologic causes of xerostomia, iatrogenic effects of medications are the most common cause. A medication which is known to cause xerostomia may be termed xerogenic. Over 400 medications are associated with xerostomia. Although drug induced xerostomia is commonly reversible, the conditions for which these medications are prescribed are frequently chronic. The likelihood of xerostomia increases in relation to the total number of medications taken, whether the individual medications are xerogenic or not. The sensation of dryness usually starts shortly after starting the offending medication or after increasing the dose. Anticholinergic, sympathomimetic, or diuretic drugs are usually responsible. Sjögrens syndrome
Xerostomia may be caused by autoimmune conditions which damage saliva-producing cells. Sjögrens syndrome is one such disease, and it is associated with symptoms including fatigue, myalgia and arthralgia. The disease is characterised by inflammatory changes in the moisture-producing glands throughout the body, leading to reduced secretions from glands that produce saliva, tears and other secretions throughout the body. Primary Sjögrens syndrome is the combination of dry eyes and xerostomia. Secondary Sjögrens syndrome is identical to primary form but with the addition of a combination of other connective tissue disorders such as systemic lupus erythematosus or rheumatoid arthritis. Celiac disease
Xerostomia may be the only symptom of celiac disease, especially in adults, who often have no obvious digestive symptoms.