What causes an increase in saliva production?

Causes of Increased Saliva Production

Medications, foods, and certain medical conditions can cause increased saliva production (sialorrhea), with cholinergic medications like pilocarpine being the most potent stimulants of salivary flow. 1, 2

Pharmacological Causes

Medications That Directly Stimulate Salivary Flow

• Cholinergic medications:
  • Acetylcholinesterase (AChE) inhibitors: Commonly used for Alzheimer's disease treatment, these are notable causes of increased saliva production 1
  • Pilocarpine: A direct cholinergic parasympathomimetic agent that significantly increases salivary gland secretion 2
    • Clinical studies show dose-dependent increases in salivary flow with pilocarpine (63% increase with 5mg dose and 90% increase with 10mg dose) 2
    • Peak effect occurs at approximately 1 hour with duration of 3-5 hours 2

Other Medications Associated with Sialorrhea

• Sedatives (benzodiazepines)
• Neuroleptics/antipsychotics
• Certain antibiotics
• Analgesics and antipyretics
• Opioids
• Vaccines 1, 3

Physiological and Dietary Stimulants

Food-Related Factors

• Acidic foods: Stimulate saliva production more effectively than other food types 1
• Foods with high sugar content: Increase salivary secretion 1
• Caffeine-containing beverages: Stimulate salivary flow 1
• Chewing: Mechanical stimulation significantly increases salivary flow (up to 1.41 ± 0.61 mL/min compared to resting flow of 0.52 ± 0.22 mL/min) 1

Neurological and Medical Conditions

Neurological Disorders

• Dysphagia: Common in neurological disorders like Parkinson's disease and post-stroke conditions - increases saliva in the mouth due to reduced swallowing frequency rather than increased production 1, 3
• Parkinson's disease: Often presents with drooling due to reduced swallowing frequency 1

Other Medical Factors

• Oral/gum diseases: Can stimulate increased salivary flow as a protective mechanism 1, 4
• Acute infections: May trigger increased salivary production 1
• Psychological factors: Stress can affect salivary composition, though typically anxiety causes dry mouth rather than increased production 5

Physiological Variables Affecting Salivary Flow

Demographic Factors

• Sex differences: Men typically have higher salivary flow rates than women 1
• Age: Salivary flow rate typically declines with age (important to note as a baseline) 1

Stimulation Methods

• Unstimulated (resting) saliva: Baseline flow rate averages 0.52 ± 0.22 mL/min 1
• Mechanically stimulated saliva: Highest flow rate at 1.41 ± 0.61 mL/min 1
• Acid-stimulated saliva: Intermediate flow rate of 0.79 ± 0.34 mL/min 1

Clinical Implications and Management

When evaluating a patient with increased salivation:

1. Review medication list: Particularly focus on cholinergic medications, AChE inhibitors, sedatives, and neuroleptics
2. Assess swallowing function: Determine if the issue is truly increased production or reduced clearance
3. Consider dietary factors: Recent consumption of acidic, sugary, or caffeine-containing foods/drinks
4. Evaluate for neurological disorders: Especially if accompanied by other neurological symptoms

Potential Complications

• Social implications: Patients with excessive salivation may face social embarrassment 3
• Medical risks: Increased risk of aspiration pneumonia in patients with both increased production and impaired swallowing 3
• Oral health impact: While appropriate salivary flow is protective against dental caries, excessive saliva can create management challenges 4

When managing a patient with sialorrhea, identifying the underlying cause is essential for appropriate treatment, with medication review being the most immediately actionable intervention.