Posted August 20, 2022 by Anusha ‐ 6 min read

Xerostomia, commonly known as dry mouth, is a condition in which the person’s salivary glands don't make enough saliva to keep the mouth wet. It is generally seen as a side-effect of certain medications, symptom of some medical disorders or as an adverse effect of radiation in cancer therapy. Rarely, the cause may be directly related to the salivary gland itself.

Other names

Also known as Dry Mouth, Xerotos and Waterlessness



This is the most common cause of xerostomia. Many medications that are sold over-the-counter mention dry mouth as the side-effect. Some medicines that are known to cause xerostomia are:

  • Medications for anxiety and depression

  • Drugs like anticholinergics that are used in the treatment of urinary incontinence, overactive bladder, and chronic obstructive pulmonary disorder

  • Decongestants and antihistamines used in allergies and cold

  • Some pain medicines

  • Some drugs are used in the treatment of high blood pressure

  • Certain bronchodilators used to treat asthma

  • Some medicines used in treatment of diarrhea

  • Certain muscle relaxants

  • Medications for Parkinson’s disease

  • Drugs used in chemotherapy for the treatment of cancer

Radiation therapy

Radiation treatments to the head and neck region for treatment of cancer can cause irreversible damage to the salivary glands. This can lead to a significant decrease in salivary production.


Dehydration occurs when the body loses a lot of fluids without getting replenished. This can happen during hot summer months or conditions like vomiting, diarrhea, fever, excessive sweating, blood loss, or burns. When the body is dehydrated, production of saliva is reduced leading to dry mouth.

Mouth-breathing or snoring

Breathing through the mouth due to nasal congestion or snoring while sleeping causes saliva to evaporate. This leads to dryness in the mouth.

Medical conditions

Xerostomia can be a sign of medical conditions like:

  • Sjogren’s disease (formerly known as Sjogren syndrome)

  • Acquired immunodeficiency syndrome (AIDS)

  • Poorly controlled diabetes

  • Uncontrolled hypertension (high blood pressure)

  • Anemia

  • Hypothyroidism

  • Sinusitis

  • Sleep apnea

  • Cystic fibrosis

  • Mumps

  • Yeast infections

  • Rheumatoid arthritis

  • Systemic lupus erythematosus

  • Parkinson’s disease

  • Alzheimer’s disease


People might experience xerostomia as they age. The factors contributing to it can be the use of certain medications, changes in the body’s ability to process medication, inadequate or improper nutrition, or long-term health problems.

Nerve damage

Any injury, infection, or surgery that causes damage to the nerves of the head or the neck region can result in xerostomia.

Smoking and drinking

Alcohol acts as a diuretic, meaning, as the body breaks down alcohol, it removes the water from the blood through urine. Also, smoking reduces the salivary flow rate leading to dryness of the mouth or xerostomia.

Use of recreational drugs

Meth mouth is a condition due to the use of methamphetamine that causes severe xerostomia and damage to teeth. Other drugs such as marijuana also can cause xerostomia.

Stress and anxiety

Cortisol (also called the stress hormone) is produced in excess when a person is under stress or is anxious. Increased levels of cortisol in saliva can change the composition of the saliva causing the mouth to become dry.

Risk factors

  • Medications like antidepressants and anxiolytics (anti-anxiety)

  • Autoimmune conditions like Sjogren’s disease and AIDS

  • Old age

  • Bulimia or anorexia

  • Blockage of major salivary duct such as from a salivary stone or infection

  • Smoking

  • Chemotherapy and radiation to the head and neck

  • Mouth breathing

  • Patients with mental or nervous disorders

  • Individuals wearing dentures

  • Pregnancy or breastfeeding


Medical history

Details about duration, frequency, and severity of dry mouth are documented. The history of dryness at other sites (eyes, nose, throat, skin & vagina) along with complete prescription drug history, health conditions, and any other symptoms along with it are obtained.

Physical examination

Major salivary glands are examined for the presence of any pain, firmness, or enlargement. The amount and quality of saliva coming from the ducts inside the mouth is assessed.

Examination of the mouth

  • There may be very little or no pooled saliva on the floor of the mouth. The saliva may appear stringy, ropy, or foamy.

  • The presence of dry, sticky or reddish oral mucosa is inspected.

  • Occasionally, fungal or yeast infections will be present, appearing as removable white plaques on the inner mucosal surface of the mouth.

  • Several office tests and techniques can be utilized to detect the abnormal functioning of the salivary glands.

These tests are as follows:


  • Also known as salivary flow measurement, it is a simple test or procedure that measures the flow rate of saliva.

  • In this test, collection devices are placed over the parotid gland or the submandibular/sublingual salivary gland at the opening of the duct, and saliva is stimulated with citric acid.

  • The normal salivary flow rate for the parotid gland when it is not stimulated is 0.4 to 1.5 mL/min/gland.

  • The normal flow rate for resting the whole saliva is 0.3 to 0.5 mL/min; for stimulated saliva, 1 to 2 mL/min.

  • Values less than 0.1 mL/min are generally considered xerostomic.


It is an imaging technique that may be used to detect any masses or stones in the salivary gland. It involves the injection of radio-opaque dye into the salivary glands.

Salivary scintigraphy

It can be useful in assessing salivary gland function. Technetium-99m sodium pertechnate is injected intravenously to ascertain the rate and density of uptake and the time of excretion in the mouth.


Minor salivary gland biopsy is often used in the diagnosis of Sjögren’s syndrome (SS), HIV-salivary gland disease, sarcoidosis, amyloidosis, and graft-versus-host disease (GVHD). Biopsy of major salivary glands is an option when malignancy (cancer) is suspected.

Blood tests

In addition to accessing the salivary glands, some blood tests may also help in detecting any underlying infection or disease. The tests are:

  • Complete blood count (CBC)

  • Blood sugar tests

  • Electrolyte levels


Saliva substitutes

  • These can be used as artificial saliva that help replace the lost moisture and lubricate the mouth.

  • These substitutes are available commercially, but they can also be compounded.

  • Artificial salivas do not stimulate salivary gland production but are designed to mimic natural saliva.

  • Thus, they are considered as replacement therapy rather than a cure.

  • These salivary substitutes are available commercially as solutions, sprays, gels, and lozenges.

  • In general, they contain an agent to increase viscosity such as carboxymethylcellulose or hydroxyethylcellulose, minerals such as calcium and phosphate ions and fluoride, preservatives such as methylparaben or propylparaben, and flavoring and related agents.

Saliva stimulants

  • A recently developed product called natrol dry mouth relief, which has a patented pharmaceutical grade of anhydrous crystalline maltose (ACM) is used to stimulate saliva production.

  • It has been used in a clinical study of patients with Sjogren’s syndrome and ACM was shown to increase secretions.

  • Natrol dry mouth relief is formulated as lozenges that can be dissolved in the mouth three times daily.

  • As its effect is to stimulate salivary glands, it is not recommended for patients whose salivary gland function has been lost through radiation therapy.


Pilocarpine: Pilocarpine is a muscarinic (M3) agonist which stimulates the secretion of saliva. It is indicated for the treatment of symptoms of xerostomia due to salivary gland hypofunction caused by Sjogren’s syndrome or by radiotherapy for cancer of the head and neck area.

Cevimeline: Cevimeline is a cholinergic agonist with a high affinity towards the muscarinic M3 receptors located on lacrimal and salivary gland epithelium, leading to an increase in the secretions of the exocrine glands. It is used to relieve the symptoms of xerostomia in patients with Sjogren’s syndrome.

dentistry dry-mouth xerostomia diseases disorders

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