64% of dry mouth is associated with medication use. Most commonly prescribed medicines such as antidepressants, anticholinergic (for gut, bladder and lung issues), anxiety medication (sleeping pills sedatives), anticonvulsant, antihistamines (allergy medication), narcotic analgesics (pain medications), hypertensive drugs (blood pressure and diuretics) and anti-inflammatory agents. All cause dry mouth.
There is a direct correlation between your age and the number of different medications you are on. This has given rise to the term "polypharmacy". If you are young and only on one medication your chance of having dry mouth is 25%. However if you are over 50 years of age and you take six or more medications then your chances of having dry mouth are 70%.
Illness is also a major cause of dry mouth. Virtually all illness causes dry mouth (xerostomia). The illnesses are then compounded by the medications to treat the condition. So now we have polypharmacy and illness working in tandem to cause dry mouth. Specific illness that cause dry mouth are; cancer, diabetes, Sjogrens's syndrome, heart disease, high blood pressure, rheumatoid arthritis, hepatitis, sleep disorder, Gastro-oesophageal reflux disease (GERD), Chronic obstructive pulmonary disease (COPD), obesity,anxiety, lupus/scleroderma, pneumonia, asthma, allergies, depression, HIV/AIDS.
Sjogren's Syndrome is the most common dry mouth illness. Sjogren's syndrome (SS), is a chronic inflammatory autoimmune disease where the immune cells attack and destroy the function of glands that produce tears and saliva. Sjogren's occurs predominantly in postmenopausal women. It is estimated that as many as 3 percent of Americans suffer from Sjogrens's syndrome, with 90 percent of these patients being women with a mean age at diagnosis of 50 years.
Enlargement of major salivary glands occurs in about one-third of patients with SS. This is thought to occur due to the saliva cells confusing signals sent to them from the brain. There is no cure for Sjogren's syndrome. The goal of therapy is to manage the symptoms. Common symptoms associated with SS, in addition to xerostomia and xerophthalmia, include blurred vision, recurrent eye and mouth infections, dysphagia or difficulty swallowing, oral soreness, smell and taste alternations, fissures on the tongue and lips, fatigue, dry nasal passages and throat, constipation and vaginal dryness.