Xerostomia · What Is It, Causes, Treatment, and More

Xerostomia, also known as dry mouth, can be a consequence of decreased saliva production or flow but may also arise in the absence of a measurable decrease in saliva quantity or flow. Saliva lubricates and cleans the oral cavity, including the oral mucosa. It aids in enhancing an individual’s ability to taste and makes it easier to chew and swallow food. It also helps maintain oral health by neutralizing acids produced by bacteria and preventing dental caries. Xerostomia has several associated symptoms, including a burning sensation in the mouth, dysphagia (i.e., difficulty swallowing), and decreased taste perception. Individuals with xerostomia may be at higher risk for dental caries and secondary oral fungal infections. 

Xerostomia is commonly caused by medications as a common side effect. Medications known to cause dry mouth include anticholinergics (e.g., oxybutynin, atropine), antidepressants (e.g., citalopram, haloperidol), opioids (e.g., morphine), muscle relaxants (e.g., tizanidine, cyclobenzaprine), and antihistamines (e.g., diphenhydramine). It is commonly seen in older adults due to polypharmacy and the increase in comorbidities in this population.

Other causes of xerostomia include radiation therapy, especially to the head and neck area; chemotherapy; head and neck surgeries; autoimmune conditions (e.g., Sjögren syndrome, rheumatoid arthritis); dehydration; and oral cavity infections. For example, Sjögren syndrome is an autoimmune disease that causes chronic lacrimal and salivary gland inflammation and fibrosis; this leads to decreased production of and flow of saliva, ultimately causing chronic xerostomia.

Non-modifiable risk factors for xerostomia include certain comorbid medical conditions like cancer of the salivary gland and rheumatologic or autoimmune conditions (e.g., Sjögren syndrome). Modifiable risk factors include alcohol use, tobacco smoking, and vitamin or nutrient deficiencies (e.g., vitamin A or riboflavin deficiency).

The most common clinical manifestations of xerostomia include dry mouth or a feeling of stickiness in the mouth due to altered consistency of saliva (often colloquially referred to as “cottonmouth”). Other symptoms of dry mouth include foul breath; sore throat and hoarseness; changes in taste perception; and difficulty chewing, speaking, or swallowing. Individuals may also experience difficulty wearing dentures and have a higher risk of dental caries. Individuals with Sjögren syndrome may also have oral thrush (i.e., fungal infection of the mouth) from decreased saliva production and its associated protective properties. 

The diagnosis of xerostomia is clinical and begins with a thorough medical history and physical examination. The history may include questions evaluating the frequency and severity of symptoms (e.g., whether the individual wakes up throughout the night to drink liquids). Further history includes evaluating medication-related causes of xerostomia; comorbid conditions; and assessing all of an individual’s prescription, over-the-counter, and herbal medications. Physical examination may also aid in diagnosing xerostomia. For example, in individuals with Sjögren syndrome, there may be salivary gland enlargement and signs of saliva underproduction, including dental caries and the absence of saliva pooling underneath the tongue.

Further techniques may be used to diagnose xerostomia, including sialometry, sialography, or biopsy (if a systemic cause is suspected). Sialometry and sialography measure the flow of saliva and provide a radiographic image of the salivary glands, respectively. If there is a palpable mass on physical examination, a biopsy may be performed to determine the underlying etiology and pathology. 

The initial treatment of xerostomia includes supportive care to alleviate symptoms, such as increased hydration,  tobacco cessation, and chewing gums to increase salivary flow. Artificial saliva or a saliva substitute may also be used as it comes in multiple topical dosage forms (e.g., sprays, lozenges, gels). If symptoms persist with conservative treatment, pharmacologic options include sialogogue medications, such as pilocarpine (i.e., cholinergic agonist) or physostigmine (i.e., cholinesterase inhibitor), both of which stimulate saliva flow and production. Individuals may also be educated on nonpharmacologic strategies that may alleviate symptoms, such as maintaining good oral hygiene (e.g., brushing teeth gently twice daily with toothpaste), sipping sugarless or caffeine-free drinks, sucking on ice chips, and using lip lubricants.

Xerostomia, also known as dry mouth, can be a consequence of decreased saliva production or flow but may also occur in the absence of a measurable decrease in saliva quantity or flow. Common causes of xerostomia include use of certain medications, prior radiation or surgery to the head and neck area, chemotherapy, and autoimmune conditions. Risk factors include polypharmacy and  tobacco and alcohol use. Xerostomia is primarily a clinical diagnosis; however, several tests, such as sialography and sialometry, may aid in the diagnosis. Treatment includes supportive care measures to alleviate symptoms, such as maintaining good oral hygiene and topical agents such as artificial saliva. If symptoms persist, pharmacologic therapy with cholinergic agents and cholinesterase inhibitors may be beneficial in increasing saliva production and saliva flow rates.