Patient-friendly definition from the DentistsDirectory.org dental glossary.
Xerostomia is the medical term for dry mouth — the persistent sensation of insufficient saliva. While almost everyone experiences dry mouth occasionally (from nervousness, dehydration, or mouth breathing while exercising), chronic xerostomia results from genuine impairment of saliva-producing glands. Saliva is far more than just a lubricant — it is a complex biological fluid containing antimicrobial proteins, immunoglobulins, calcium, phosphate, and bicarbonate that actively protect teeth and oral tissues. When saliva production is reduced, oral health deteriorates rapidly.
Medications are by far the most common cause of chronic dry mouth — over 500 prescription and over-the-counter drugs list dry mouth as a side effect, particularly antidepressants, antihistamines, antihypertensives, diuretics, and medications for Parkinson's disease and anxiety. Radiation therapy to the head and neck can permanently damage the salivary glands — a serious, often irreversible complication of cancer treatment. Sjögren's syndrome is an autoimmune condition that attacks salivary and tear glands, causing severe, chronic dry mouth. Other causes include diabetes, HIV/AIDS, and systemic dehydration.
Without adequate saliva to neutralise acids and wash away plaque, patients with significant xerostomia experience dramatically accelerated tooth decay — often involving surfaces rarely affected in normal patients, such as the roots and the gum line. Gum disease also progresses more rapidly, and oral fungal infections (candidiasis) are more common. Management includes staying well hydrated, using alcohol-free fluoride mouthwash, applying prescription-strength fluoride gels, using sugar-free xylitol-containing products (gum, lozenges) to stimulate saliva, and more frequent dental check-ups (every 3–4 months rather than 6). Saliva substitute products and prescription salivary stimulants (pilocarpine, cevimeline) can help in more severe cases.