What causes xerostomia (dry mouth)?

Causes of Dry Mouth (Xerostomia)

Xerostomia (dry mouth) is primarily caused by medications, systemic diseases, and salivary gland dysfunction, with medication side effects being the most common cause in clinical practice. 1

Medication-Related Causes

Medications represent the most frequent cause of xerostomia, particularly in older adults who often take multiple medications:

• Anticholinergic medications:

  • Antidepressants (particularly tricyclics)
  • Antimuscarinics
  • Antihistamines
  • Antipsychotics
  • Antiparkinsonians 1

• Other common xerogenic medications:

  • Anxiolytics
  • Decongestants
  • Certain pain medicines
  • Diuretics
  • Calcium channel blockers
  • Lithium
  • Prolonged use of nonsteroidal anti-inflammatory drugs 1

• Polypharmacy: Taking multiple medications simultaneously significantly increases the risk of xerostomia 1

Disease-Related Causes

Several medical conditions can cause or contribute to xerostomia:

• Autoimmune disorders:

  • Sjögren's syndrome (primary or secondary) - characterized by lymphocytic infiltration of salivary and lacrimal glands 1
  • Rheumatoid arthritis (often associated with secondary Sjögren's) 1

• Salivary gland disorders:

  • Salivary gland hypofunction
  • Minor salivary gland parenchymal fibrosis and atrophy 1

• Systemic conditions:

  • Chronic kidney disease (CKD) and patients on hemodialysis 1
  • Diabetes mellitus
  • Dehydration
  • Cancer, particularly after radiation therapy to head and neck 1

Other Contributing Factors

• Age-related changes: Salivary flow rate (SFR) naturally declines with age 1

• Fluid intake restriction: Common in patients with certain medical conditions like CKD 1

• Lifestyle factors:

  • Alcohol consumption (diuretic effect)
  • Caffeine intake (diuretic effect) 1
  • Mouth breathing
  • Tobacco use

• Cancer therapy:

  • Immunotherapy-related sicca syndrome (occurs in 2-11% of patients receiving immune checkpoint inhibitors) 1
  • Radiation therapy to head and neck region

Clinical Implications

Xerostomia can lead to significant complications:

• Difficulty with chewing, swallowing, speaking, and taste perception
• Increased risk of dental caries and oral infections (particularly candidiasis)
• Denture discomfort and poor fit
• Reduced quality of life
• Poor nutrition due to eating difficulties 1

Management Considerations

For patients with xerostomia, treatment depends on the underlying cause:

• Medication-induced: Consider medication review and possible alternatives
• Disease-related: Treat underlying condition when possible
• Symptomatic treatment:
  • Saliva substitutes and moisture-preserving mouth rinses
  • Systemic sialagogues like pilocarpine (5mg three times daily) or cevimeline for moderate to severe cases 1, 2
  • Dietary modifications and increased hydration 1

Important Clinical Pitfalls

• Xerostomia may be underreported by patients unless specifically asked about
• Severe untreated xerostomia can lead to dental caries and tooth loss 1
• Patients with xerostomia often require multidisciplinary care involving dentistry and potentially rheumatology 1
• The subjective feeling of dry mouth may not always correlate with measurable decreased salivary flow

Understanding the specific cause of xerostomia is essential for effective management and preventing complications that can significantly impact a patient's quality of life and oral health.