Foaming or frothing at the mouth occurs when excess saliva pools in the mouth or lungs and mixes with air. Causes include drug overdose, seizures, pulmonary edema, and rabies. It is usually a medical emergency.
Unintentional foaming is usually a sign of a serious medical condition that requires emergency medical care. It is essential to seek immediate medical help if a person begins foaming at the mouth.
... Foaming at the mouth is normally associated with central nervous system problems with life threatening complications, including coma and death.
Colgate.com is less concerned, at least initially:
What Causes Foamy Saliva?
Foamy spit is usually the result of dry mouth. Dry mouth could be a short-term response to conditions like:
Dehydration Stress Nervousness Mouth-breathing Dry mouth could also be a symptom of many oral and whole-body conditions. The following health conditions could cause xerostomia (the fancy term for dry mouth):
Sjogren's Syndrome (an autoimmune disorder) Cancer of the salivary glands Diabetes Stroke Yeast infection (oral thrush) in your mouth Alzheimer's disease HIV/AIDS The Cleveland Clinic notes hundreds of medications, including over-the-counter medications, can also cause dry mouth, particularly the following:
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