What is dry mouth (xerostomia)? What causes dry mouth?

September 11, 2018 by Dr. Andrew Smyth  •  Original Post

Xerostomia is a medical term used for dry mouth due to lack of saliva - there is not enough saliva to keep the mouth wet; there is reduced or absent saliva flow. It is also informally known as pasties, cottonmouth, drooth, doughmouth or des(from desert). It is usually a subjective complaint - the patient complains about it and subsequently sees the doctor. 

Experts say xerostomia is usually caused by the inadequate function of the salivary glands. 

Xerostomia can lead to speech and eating difficulties, halitosis (bad breath), an increase in the number of dental cavities (saliva helps prevent tooth decay), and infections in the mouth, such as thrush. An individual with xerostomia typically finds it harder to enjoy food. 

Xerostomia is a common problem. It is frequently a side effect of medication, which may improve with a new prescription or an adjustment of dosage. 

We all get a dry mouth sometimes - when we are upset, under stress or extremely frightened. Xerostomia is different - the individual's mouth is dry most of the time. 

Some patients may think dry mouth is a normal part of aging - it is not. It is, however, more commonly found among the elderly. Experts say the main reason is that elderly people take more medications compared to the rest of the population, and some of these medications cause xerostomia. 

Xerostomia may be a symptom of a serious systemic disease, such as systemic lupus erythematosus, rheumatoid arthritis,scleroderma, sarcoidosis, amyloidosis, Sjogren's syndrome and hypothyroidism. A systemic disease is one that affects the entire body. 

In fact, xerostomia is not a disease; it is a symptom, just like headache is a symptom and not a disease.

What are the signs and symptoms of Xerostomia (dry mouth)?

A symptom is something the patient senses and describes, while a sign is something other people, such as the doctor notice. For example, drowsiness may be a symptom while dilated pupils may be a sign. The signs and symptoms of xerostomia may include:

  • Bad breath
  • Cheilitis - inflammation and fissuring of the lips
  • Cracked lips
  • Cracking and fissuring of the oral mucosa (inner lining of the cheeks and lips)
  • Dryness in the mouth
  • Dysgeusia - taste disorders
  • Fungal infections in the mouth, such as thrush
  • Glossodynia - painful tongue
  • Increased need to drink water, especially at night
  • Inflammation of the tongue, tongue ulcers
  • Lipstick sticking to teeth
  • More frequent gum disease
  • More tooth decay and plaque
  • Problems speaking
  • Problems swallowing and chewing - especially dry and crumbly foods, such as crackers or cereals.
  • Problems wearing dentures - problems with denture retention, denture sores and the tongue sticking to the palate.
  • Sialadenitis - salivary gland infection
  • Sore throat
  • Sticky saliva
  • Stringy saliva
  • The skin at the corners of the mouth may split, or be sore.

What are the causes of xerostomia (dry mouth)?

Xerostomia may be a sign of an underlying disease or condition, such as Sjogren's syndrome, diabetes (poorly controlled), or Lambert-Eaton syndrome. It may also be caused by some medications. Some possible causes include: 

Medications - many prescription and OTC (over-the-counter, no prescription required) medications cause dry mouth, including antihistamines, hypertensive medications (for high blood pressure), anti-diarrheals, muscle relaxants, urinary continence drugs, someParkinson's disease medications, as well as a number of antidepressants. 

Age - even though old age is not a dry mouth risk factor, elderly individuals tend to take more medications than the rest of the population. Many of the medications taken by seniors cause dry mouth. 

Cancer treatment - radiotherapy (radiation therapy) to the head and neck can damage the salivary glands, resulting in less saliva being produced. Chemotherapy can alter the nature of the saliva, as well as how much of it the body produces. 

Injury or surgery - which results in nerve damage to the head and neck area, can result in dry mouth. 

Tobacco - either chewing or smoking tobacco increases the risk of dry mouth symptoms. 

Dehydration - caused by lack of sufficient fluids. 

Exercising or playing in the heat - the salivary glands may become dry as the bodily fluids are concentrated elsewhere in the body. Dry mouth symptoms are more likely if the exercise or playing continues for a long time. 

Some health conditions, illnesses and habits - such as:

  • Anxiety disorders
  • Depression
  • Parkinson's disease
  • Poorly controlled diabetes
  • Sjogren's syndromes
  • Sleeping with the mouth open
  • Snoring
  • Stroke and Alzheimer's disease - more likely to cause a perception of dry mouth.

Diagnosing xerostomia (dry mouth)

The doctor or dentist will probably examine the patient's mouth and review their medical history. Blood tests and imaging scans of the salivary glands may also be ordered. 

Sialometry - this is a simple office procedure that measures the flow rate of saliva. Collection devices are placed over the parotid gland or the submandibular/sublingual gland duct orifices, and saliva is stimulated with citric acid. 

Saliography - this is radiographic examination of the salivary glands and ducts after the introduction of a radiopaque material into the ducts. It may be useful in identifying salivary gland stones and masses. 

Biopsy - a small sample of salivary gland tissue is taken. Often used in the diagnosis of Sjogren's syndrome. If malignancy (cancer) is suspected the doctor may also order a biopsy. 

Many healthcare professionals report that often the visual condition of the oral mucosa (inner lining of the cheeks and lips) does not correlate to the subjective feeling of "dry mouth" by the patient - even though the patient complains of severe dry mouth, the oral mucosa appears to be moist. Less frequently, it may be the other way round; the oral mucosa appears dry but the patient does not complain of dry mouth symptoms.

What are the treatment options for xerostomia (dry mouth)?

Treatment for xerostomia depends on several factors, such as whether the patient has an underlying condition or disease, or is taking certain medications that may be causing dry mouth. 

Ideally, the underlying cause is found. This does not always happen. If it is found steps need to be taken to minimize its effect. 

Medications - if the dry mouth is thought to be caused by a medication, the doctor will either alter the dosage or prescribe another drug which is less likely to cause dry mouth. 

Stimulating saliva production - a medication may be prescribed, such as pilocarpine (Salagen) or cevimeline (Evoxac), to stimulate the production of saliva. 

Experts say that symptomatic treatment for dry mouth typically includes four areas:

  • Increasing the flow of saliva
  • Replacing lost secretions
  • Controlling dental caries
  • Some specific measures, such as treating infections.

A patient with xerostomia should pay special attention to oral/dental hygiene. This includes plaque removal and treatment of gingival infections, inflammation and dental caries. Brushing teeth and flossing regularly is important. 

Sipping fluids (non-carbonated, sugarless), chewing xylitol-containing gum, and using a carboxymethyl cellulose saliva substitute as a mouthwash may help. 

Mouthwashes which contain alcohol should be avoided, because they may worsen dry mouth symptoms. 

The patient should conduct a daily mouth examination, looking out for unusually colored patches, tooth decay or ulcers. Anything unusual should be reported to their doctor or dentist. 

The patient should not wear dentures during sleep. The dentures must be kept clean by overnight soaking. 

Individuals with xerostomia should avoid:

  • Sugary foods or drinks
  • Acidic foods or drinks
  • Dry foods
  • Spicy foods
  • Astringents
  • Excessively hot or cold drinks.

Alcohol consumption should be kept to a minimum or avoided altogether. 

Caffeine consumption should be kept to a minimum. 

Chewing or smoking tobacco should be avoided. 

Eating such foods as carrots or celery may help with residual salivary gland function. 

Breathing - breathing through the nose does not dry the mouth, while breathing through the mouth does. 

Humidity - a humidifier can add moisture to a bedroom. This may help reduce dry mouth symptoms that develop during sleep.
Written by Christian Nordqvist

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