Drooling

There are some frequent and harmless cases of drooling – for instance, a numbed mouth from either benzocaine, or when going to the dentist's office.

Isolated drooling in healthy infants and toddlers is normal and may be associated with teething. It is unlikely to be a sign of disease or complications. Drooling in infants and young children may be exacerbated by upper respiratory infections and nasal allergies.

Some people with drooling problems are at increased risk of inhaling saliva, food, or fluids into the lungs, especially if drooling is secondary to a neurological problem. However, if the body's normal reflex mechanisms (such as gagging and coughing) are not impaired, this is not life-threatening.

Causes

Drooling or sialorrhea can occur during sleep. It is often the result of open-mouth posture from CNS depressants intake or sleeping on one's side. Sometimes while sleeping, saliva does not build up at the back of the throat and does not trigger the normal swallow reflex, leading to the condition. Freud conjectured that drooling occurs during deep sleep, and within the first few hours of falling asleep, since those who are affected by the symptom experience the most severe harm while napping, rather than during overnight sleep.

A sudden onset of drooling may indicate poisoning – especially by pesticides or mercury – or reaction to snake or insect venom. Excess capsaicin can cause drooling as well, an example being the ingestion of particularly high Scoville Unit chili peppers. Some neurological problems cause drooling. Medication can cause drooling, either due to primary action or side-effects; for example the pain-relief medication Orajel can numb the mucosa.

Causes include:

• exercise, especially cardiovascular exercise
• stroke and other neurological pathologies
• intellectual disability
• adenoid hypertrophy
• cerebral palsy
• amyotrophic lateral sclerosis
• tumors of the upper aerodigestive tract
• Parkinson's disease
• rabies
• mercury poisoning

Drooling associated with fever or trouble swallowing may be a sign of an infectious disease including:

• retropharyngeal abscess
• peritonsillar abscess
• tonsilitis
• mononucleosis
• strep throat
• obstructive diseases (tumors, stenosis)
• inability to swallow due to neurodegenerative diseases (amyotrophic lateral sclerosis)