What causes xerostomia?

Causes of Xerostomia

Xerostomia is most commonly caused by medications with anticholinergic properties, followed by autoimmune diseases affecting salivary glands, chronic systemic diseases (diabetes mellitus, chronic kidney disease), and polypharmacy. 1

Medication-Induced Xerostomia

The most prevalent cause of xerostomia is medication use, particularly in elderly patients who are typically on multiple drugs. 1, 2, 3

High-Risk Medication Classes:

• Anxiolytics and antidepressants (particularly tricyclic antidepressants) 1
• Antimuscarinics 1
• Antihistamines 1, 4
• Decongestants 1
• Antiparkinsonians 1
• Some pain medicines and antipsychotics 1
• Diuretics 1, 4
• Calcium channel blockers 1, 4
• Lithium 1, 4
• Cardiac antiarrhythmic drugs and beta-adrenergic antagonists 4
• Chemotherapy agents 4

Xerostomia is particularly common in polypharmacy, where the cumulative anticholinergic burden from multiple medications compounds the effect. 1

Medical Conditions Causing Xerostomia

Autoimmune Diseases:

• Sjögren's syndrome presents with the classic "sicca complex" of dry eyes and dry mouth 1, 4
• Other autoimmune conditions including rheumatoid arthritis, systemic lupus erythematosus, and scleroderma 4
• Primary biliary cholangitis can present with sicca symptoms 1

Endocrine Disorders:

• Diabetes mellitus (both through direct glandular effects and as part of systemic disease) 1, 4, 5
• Thyroid dysfunction (both overactive and profoundly underactive thyroid) 1, 4, 6

Renal Disease:

• Chronic kidney disease affects salivary gland function and can cause xerostomia 1, 4, 3

Neurological Conditions:

• Parkinson's disease 4
• Bell's palsy 4
• Trigeminal neuralgia 4
• Most neurological diseases are potentially relevant to xerostomia 1

Sleep Disorders:

• Obstructive sleep apnea and other sleep disorders can contribute to dry mouth, particularly at night 4

Other Contributing Factors

Radiation Therapy:

• High doses of radiation to the head and neck can permanently damage salivary glands 2, 5, 6

Systemic Conditions:

• Dehydration 5, 3
• Chronic mouth breathing 6
• Nephritis 6

Age-Related Changes:

• While salivary gland function is generally well-preserved in healthy elderly individuals, saliva undergoes chemical changes with aging (decreased ptyalin, increased mucin), making it thick and viscous 6
• Aging itself is not a direct cause, but elderly patients are at greater risk due to increased medication use 2, 6

Clinical Pitfalls to Avoid

Failing to review all medications, including over-the-counter products and supplements, is a common diagnostic error that leads to missed medication-induced xerostomia. 4

Overlooking sleep disorders as contributors to nocturnal dry mouth can result in inadequate treatment, as mouth breathing during sleep apnea episodes significantly worsens xerostomia. 4

Not distinguishing between true xerostomia and compensatory increased fluid intake due to other conditions (such as diabetes insipidus or poorly controlled diabetes mellitus) is important for appropriate management. 1