What are the causes and workup for dry mouth (xerostomia) and dry eyes (xerophthalmia) at night?

Causes and Workup for Dry Mouth and Dry Eyes at Night

The most common causes of dry mouth (xerostomia) and dry eyes (xerophthalmia) at night include medications with anticholinergic effects, systemic autoimmune conditions (particularly Sjögren's syndrome), and sleep disorders, which should be systematically evaluated through a comprehensive history, medication review, physical examination, and targeted laboratory testing. 1

Common Causes

Medication-Related Causes

• Systemic medications with anticholinergic effects including antihistamines, diuretics, antidepressants, cardiac antiarrhythmic drugs, beta-adrenergic antagonists, and chemotherapy agents 1
• NSAIDs, calcium channel blockers, and lithium can contribute to xerostomia 1
• Medication side effects may account for up to 62% of sicca symptoms (dry eyes and dry mouth) in elderly populations 2

Systemic Conditions

• Autoimmune diseases, particularly Sjögren's syndrome (primary or secondary), which presents with the classic "sicca complex" of dry eyes and dry mouth 3
• Other autoimmune conditions: rheumatoid arthritis, systemic lupus erythematosus, scleroderma 1
• Endocrine disorders: diabetes mellitus, thyroid dysfunction (both hyper- and hypothyroidism) 1
• Chronic kidney disease can cause both xerostomia and xerophthalmia 1

Sleep-Related and Neurological Causes

• Obstructive sleep apnea (OSA) and other sleep disorders 1
• Neurological conditions including Parkinson's disease, Bell's palsy, trigeminal neuralgia 1
• Aging-related changes in salivary and lacrimal gland function 2

Comprehensive Workup

Detailed History

• Symptom assessment: severity, timing (worse at night), exacerbating factors, and duration 1
• Associated symptoms: joint pain, fatigue, oral ulcers, dental cavities 1
• Sleep patterns: difficulty falling or staying asleep, snoring, gasping during sleep 1
• Complete medication review, including over-the-counter medications and supplements 1

Physical Examination

• Ocular examination: tear film quality and quantity, corneal staining, conjunctival redness 1
• Oral examination: salivary flow, oral mucosa condition, dental status 1
• Eyelid examination: incomplete closure, abnormal blinking patterns, eyelid malposition 1
• Systemic examination: joint deformities, skin changes (scleroderma, rosacea), cranial nerve function 1

Laboratory and Diagnostic Testing

• Blood tests: electrolytes, renal function, thyroid function, HbA1c, calcium levels 1
• Autoimmune markers when Sjögren's syndrome is suspected: antinuclear antibody (ANA), rheumatoid factor (RF), anti-Ro/SS-A and anti-La/SS-B antibodies 3, 4
• Tear film assessment: Schirmer test to measure tear production 5
• Salivary flow measurement: unstimulated salivary flow rate 5

Special Considerations

Sjögren's Syndrome Evaluation

• Consider Sjögren's syndrome particularly when both dry eyes and dry mouth are present (occurs in approximately 14% of patients with sicca symptoms) 5
• Note that there is only a weak association between subjective symptoms and objective test results in the general population 5
• Autoantibody testing may not be helpful in all cases, as many patients with sicca symptoms do not have detectable autoantibodies 2

Age-Related Factors

• Prevalence of dry mouth symptoms increases with age, female sex, and white race 2
• Associations between symptoms and objective findings are stronger in patients under 55 years of age 5

Treatment Considerations

• For medication-induced symptoms, consider medication adjustment when possible 2
• For Sjögren's syndrome, pilocarpine has high-quality evidence for reducing dry mouth symptoms and increasing salivary flow 4
• Pilocarpine dosing typically starts at 5 mg three times daily, with common side effects including sweating, nausea, rhinitis, and diarrhea 6

Common Pitfalls to Avoid

• Failing to review all medications, including over-the-counter products 1
• Overlooking sleep disorders as potential contributors to nocturnal symptoms 1
• Assuming all sicca symptoms indicate autoimmune disease, when medication effects are more common 2
• Relying solely on subjective symptoms without objective testing, as correlation between symptoms and test results can be weak 5