Why does dry mouth occur?

Everyone has experienced the sensation of the mouth watering. Smelling, seeing or tasting something delicious immediately triggers saliva production. Saliva flow also increases when chewing.

However, some people have undoubtedly experienced the opposite - a dry mouth caused by nerves or fear. The tongue sticks to the gums and speaking and swallowing becomes much more difficult.

Causes of dry mouth

Various causes can lead to these symptoms and therefore to a disruption of saliva production and dry mouth (xerostomia).

A side effect of many medications, including medication for depression, high blood pressure, asthma or Parkinson's disease is reduced saliva production. Since the flow of saliva is reduced in more than 30% of over 65-year-olds due to old age, this is exacerbated by the additional intake of medication.

Acute or chronic inflammation of the salivary glands (sialadenitis) leads to the reduced secretion of saliva. It can also be caused by bacteria or viruses (e.g. mumps). Salivary gland stones that can block the salivary glands lead to inflammation and reduce the flow of saliva. Both benign and malignant tumours can cause reduced salvia production. Furthermore, systemic illnesses, such as diabetes mellitus, thyroid gland or kidney disease, can affect the saliva content in the mouth. Sjögren's syndrome (an autoimmune disease) can also lead to a dry mouth. Radiation therapy to the head for cancer in the mouth, jaw and face can permanently damage the salivary glands.

Consequences of dry mouth

Due to the variety of possible causes, it is assumed that almost 50% of the population suffers from dry mouth.

Inflammation in the salivary glands, various illnesses, medication, radiation or old age can reduce the flow of saliva, which leads to dry mouth (xerostomia). Since elderly people often take various medications, this can exacerbate the effect of dry mouth. There are various consequences of xerostomia and can lead to a significant restriction in quality of life.
Reduced moisture of the oral mucosa makes speaking, chewing and swallowing more difficult. A lack of saliva makes it difficult to tear up food and reduces the smoothness of biting. This results in pain when chewing and swallowing. In addition, hard food can cause injuries in the oral cavity. If food is not predigested in the mouth with salivary enzymes, this can lead to digestion problems. Dry mouth can also cause taste impairments. 
If the rinsing effect of saliva is not produced due to a reduced flow of saliva, harmful bacteria cannot be completely transported out of the mouth. The protective antibacterial and antiviral effect is also weakened. This can lead to inflammation of the oral mucosa, such as on the gums, burning mouth syndrome or bad breath.

Negative impacts on dental health

Dry mouth can also have negative impacts on dental health. Not only is the self-cleaning function reduced due to a lack of the rinsing effect, saliva no longer supplies the minerals and the teeth are not protected against acid attacks. Both the metabolic products of various bacteria and the acids from foodstuffs and drinks remove minerals from the teeth. When the flow of saliva is normal, saliva can act as a buffer against these acids while providing mineral salts to the teeth for remineralisation. If saliva production is reduced, acids cannot be neutralised and the teeth are not provided with the required minerals. Therefore, a lack of saliva significantly increases the risk of caries. 

Symptoms of dry mouth

If you answer yes to the questions below, it is highly likely that you suffer from dry mouth (Villa et al. 2015, van der Putten et al. 2011).

  • My mouth and/or throat feel dry.
  • My lips feel dry and/or are often cracked.
  • I feel like I do not have enough saliva.
  • I am always thirsty.
  • I need a drink when I wake up during the night.
  • I have difficulties eating dry food.
  • I cannot eat anything without drinking something at the same time.
  • I often eat boiled sweets or chew gum.
  • I have difficulties swallowing.
  • I often breathe through my mouth.
  • I do not drink enough (i.e. less than 1 litre per day).
  • I am often stressed.
  • I take medication on a regular basis.

- Villa, A., Connell, C. L. & Abati, S. Diagnosis and management of xerostomia and hyposalivation. Ther. Clin. Risk Manag. 11, 45-51 (2015).
- Putten, G. J. v. d., Brand, H. S., Schols, J. M. & Baat, C. d. The diagnostic suitability of a xerostomia questionnaire and the association between xerostomia, hyposalivation and medication use in a group of nursing home residents. Clin. Oral Investig. 15, 185-192 (2011).