As has been pointed out in our previous article, xerostomia or “dry mouth” is the feeling of lack of saliva due to malfunction of the salivary glands. We have also noted above the relevant function of saliva in bucal hygiene and as moisturer, which is required for chewing, swallowing and even speaking.
We keep refering to xerostomia and “dry mouth” as synonymous and we will use these terms interchangeably.
Although xerostomia is caused by an abnormal function of the salivary glands, lack of saliva has an important subjective component. Not everyone perceives “dry mouth” the same way. Furthermore there are environmental or personal factors (like some foods consumption, hygiene habits, tabaquism, alcoholism or aging) involved level of moisture level in the mouth.
Beyond any subjective perception, the real lack of saliva has many causes and depending on the specific cause, xerostomia can be total or partial and reversible or irreversible.
The different classes of xerostomia will be discussed at length in next articles.
What causes xerostomia or dry mouth?
Xerostomia commonly occurs as a side effect of some medications but it can also be caused by autoimmune disorders, salivary gland diseases or some cancer therapies, among other causes that we will examine below.
Xerostomia as side effect of drugs
Xerostomia is a common side effect of hundred of drugs such as antihistamines, antidepressants, anti-inflammatories, etc.
If you start to use a drug and you feel “dry mouth”, keep calm and read carefully the package leaflet of the drug and check if xerostomia is a possible side effect and contact your doctor.
This type of xerostomia is usually reversible and dissapears when the drug treatment finishes.
Xerostomia due to autoimmune diseases
Some systemic disorders (affecting the entire body) as autoimmune diseases or Diabetes cause the destruction of gland parenchyma (functional tissues) which decreases salivary secretion. This class of xerostomia is usually irreversible because the glands cannot recover their functionality.
Autoimmune diseases that commonly cause mucosal dryness and thus xerostomia are:
- Sjögren’s syndrome
- Rheumatoid arthritis
- Systemic lupus erythematosus
Other systemic disorders that can cause xerostomía include:
- Diabetes mellitus
- Cystic fibrosis
- Endocrine disorders
- Thyroid disfunction
- Nutritional deficiencies
- Neurological disorders as stroke, Alzheimer’s, Parkinson’s, Bell’s palsy…)
In most of these diseases xerostomia is temporary or reversible. For example, in hypertension or depression, the dry mouth is the result of a temporary problem of nerves and blood vessels.
Xerostomia due to salivary gland disorders
Dry mouth is one of the most common symptoms of salivary gland disorders. Other symptoms are altered taste, problems in opening the mouth, facial pain, face or neck swelling…
-Xerostomia may be caused by stones or calculi (sialoliths) inside the salivary ducts that block the flow of saliva. Sialoliths are the most common diseases of the salivary glands but they are self-limiting and not dangerous.
-Some viral or bacterial infections (such as mumps) can cause inflammation of salivary glands and decrease the production of saliva.
-Salivary glands or ductal tumors. They are usually benign and very slow-growing.
Salivary gland disorders will be exposed in a more extensive way in next articles.
Xerostomia due to chemotherapy or radiation therapy
Application of chemotherapy or radiotherapy to the head, face or neck may also cause dry mouth due to damage to the salivary glands.
Xerostomia caused by chemotherapy is usually temporary and disappears about 2-8 weeks after finishing treatment.
After radiation therapy, it can take up to 6 months or longer for salivary gland to recover. Although many people experience some level of dry mouth permanently (especially if the treatment was directed at the salivary glands)