Drooling (Sialorrhea)  refers to the unintentional loss of saliva from the mouth, typically resulting from impaired salivary control. This may stem from:

• Failure to swallow (e.g., due to neurological or muscular disorders),

• Excessive salivation (e.g., drug-induced or toxin-related),

• Inability to retain saliva due to facial weakness, pain, or anatomical disruption.

Severity may range from mild (scant) to severe (copious, up to 1L/day), often resulting in perioral skin irritation and posing a significant aspiration risk.

Pathophysiology of Drooling (Sialorrhea)

Drooling occurs due to an imbalance between saliva production, clearance, and swallowing capacity. It is often multifactorial, involving neuromuscular, anatomical, or pharmacological components. The main mechanisms include:

1. Impaired swallowing Reflex (Dysphagia)

• Normal swallowing is a complex process involving cranial nerves (V, VII, IX, X, XII), coordinated muscle activity, and intact brainstem centers.

• Disruption due to:

  • Neurological conditions (e.g., cerebral palsy, Parkinson's disease, stroke, ALS)

  • Muscular diseases (e.g., myasthenia gravis, myotonic dystrophy)

  • Brainstem lesions (affecting central pattern generators for swallowing)

• This leads to pooling of saliva in the oropharynx and unintentional spillage from the mouth.

2. Excessive Saliva Production (Hypersalivation)

• Normally, adults produce ~1–1.5 L of saliva daily, mainly from:

  • Parotid (serous),

  • Submandibular (mixed),

  • Sublingual and minor glands (mucous).

• Stimulation of parasympathetic cholinergic pathways increases saliva secretion.

• Causes of hypersecretion:

  • Toxins or drugs (e.g., organophosphates, pilocarpine, clozapine)

  • Pregnancy or GERD

  • Nausea or oral infections

3. Poor Oral Motor Control / Neuromuscular Dysfunction

• Weakness, incoordination, or sensory loss in facial, labial, lingual, or palatal muscles can impair the ability to retain and manipulate saliva within the mouth.

• Seen in:

  • Cerebral palsy

  • Stroke or Bell’s palsy

  • Parkinson’s disease (bradykinesia, rigidity of oral muscles)

  • Bulbar palsy or pseudobulbar palsy

• Open mouth posture and reduced lip seal promote drooling.

4. Anatomical or Mechanical Obstruction

• Oral or oropharyngeal structural abnormalities can disrupt the flow or clearance of saliva.

• Examples:

  • Macroglossia

  • Dental malocclusion

  • Tumors (e.g., esophageal or oropharyngeal cancers)

  • Obstructive infections (e.g., peritonsillar abscess, epiglottitis)

5. Decreased Sensory Feedback or Cognitive Impairment

• Normal salivation is modulated by sensory stimuli and cortical awareness.

• In conditions such as intellectual disability, dementia, or coma, individuals may lack the awareness or coordination to swallow, resulting in accumulation and drooling.

6. Medication-Induced Sialorrhea

• Cholinergic agonists (e.g., pilocarpine, used in Sjögren’s)

• Antipsychotics (e.g., clozapine → paradoxical sialorrhea despite anticholinergic effects)

• Heavy metal toxicity (e.g., mercury, arsenic)

Clinical Assessment

History

• Onset and duration: When did drooling begin? Is it constant or episodic?

• Severity: Pillow wetting at night? Need for constant wiping?

• Associated symptoms:

  • Dysphagia, odynophagia

  • Dysarthria or anarthria

  • Facial or limb weakness

  • Cognitive changes (e.g., drowsiness, agitation)

  • Sensory deficits (vision, hearing, taste)

  • Respiratory compromise (stridor, difficulty handling secretions)

• Systemic symptoms: Fever, weight loss, nausea, vomiting

• Environmental exposure: Recent infections, bites (animal or insect), chemical/pesticide exposure

• Medication history: Especially cholinergic agents, antiepileptics, antipsychotics

Physical Examination

• General: Vital signs, hydration status

• Head and neck: Facial symmetry, oral inspection for edema, lesions, exudates

• Cranial nerves (II–VII, IX–X): Motor and sensory deficits

• Neurological: Gag reflex, swallowing ability, tone/reflexes, ataxia, Babinski sign

• Musculoskeletal: Muscle tone, strength, myotonia

• Skin and lymphatics: Rash, lesions, lymphadenopathy, signs of infection

Medical causes of drooling

Pediatric considerations

• Physiological: Normal in infants <1 year due to immature swallowing reflexes

• Developmental triggers: Teething, anticipation of feeding

• Pathologic causes:

  • Infectious: Epiglottitis, stomatitis, herpetic lesions, tonsillitis

  • Structural: Esophageal atresia, foreign body

  • Neurological: Cerebral palsy, intellectual disability

  • Neonatal: Drug withdrawal (maternal substance use)

Special clinical considerations

• Aspiration Risk: Maintain upright or side-lying position, frequent suctioning, prepare for airway support

• Skin Integrity: Prevent maceration with cornstarch; clean and dry perioral area regularly

• Oral Hygiene: Provide frequent oral care; use covered containers for secretions to limit infection and odor

• Functional Support: Encourage facial muscle exercises where appropriate

Patient Education & Counseling

• Educate patient and family on the cause of drooling and potential complications.

• Instruct on home management: swallowing techniques, hygiene routines, posture.

• Discuss therapeutic options, including:

  • Anticholinergic medications (e.g., glycopyrrolate)

  • Botulinum toxin injections

  • Speech and swallowing therapy

  • Surgical interventions (in refractory cases)