Dry mouth

Also know as xerostomia (sounds like ZEER-oh-STOH-mee-ah) or salivary hypofunction

Dry mouth is a condition where there is not enough saliva in your mouth. Dry mouth can contribute to dental decay, gum disease and infections, so you may need to take extra care of your oral health.


Dry mouth can be temporary. Many of us have experienced the ‘dry horrors’the morning after drinking a little too much alcohol – your mouth is like a desert, your tongue feels like cardboard and swallowing is almost impossible. Having a cold, or breathing through your mouth, can also cause dryness.In these cases, you know that once you get over the cause you and your mouth will be back to normal. However, if you live with these symptoms most of the time, then chances are you have dry mouth (salivary hypofunction). 

A persistently dry mouth is thought to affect at least 1 person in 10, and one in 5 older people. Sometimes a dry mouth can be a sign of more serious conditions like diabetes or Parkinson’s disease.

The many important functions of saliva

Saliva is produced by several types of salivary gland, which release saliva at numerous different positions in the mouth. Each type of gland makes a slightly different form of saliva. The result is a constantly changing composition of saliva in the mouth, to perform a range of essential functions.

  • Saliva cleans the mouth – saliva breaks down retained food particles or by-products and washes debris out towards the back of the throat, where it can be swallowed and digested.
  • Saliva lubricates the mouth – saliva prevents chafing and rubbing between the soft and hard tissues of the mouth, like the tongue and the teeth.
  • Saliva helps maintain the correct acid levels in the mouth – saliva acts as a buffer to prevent the pH levels (the measure of acidity/alkalinity) in the mouth from getting too low. When the pH level drops below 5.7 (meaning more acidity), the teeth can lose essential minerals such as calcium and phosphate. When a person eats food, the bacteria on our teeth start to digest the sugars in the food, producing acids. Saliva helps neutralise this acid (minimising the drop in pH) and helps prevent damage to the teeth from the acid.
  • Saliva remineralises the teeth – proteins in saliva bind calcium and phosphate together and coat the teeth with them, helping to maintain their enamel surface.
  • Saliva keeps harmful bugs in check – the antimicrobial properties of saliva fight unwanted bacteria, viruses and fungi.
  • Saliva allows taste and digestion – enzymes in saliva help break down the foods into a form that can both be digested and tasted. Unless food forms a solution (in this case blended with saliva), it cannot be tasted.
  • Saliva plays a part in mouth repair – saliva and mucus protect and allow regeneration of the membrane that lines the mouth, throat and nose.

Causes of dry mouth

It is important to see your doctor to explore any possible underlying causes of dry mouth. Some causes may include:

  • side effects of prescribed or illicit drugs – particularly antidepressants, antipsychotics, antihistamines, decongestants, cannabis or diuretics
  • diabetes
  • Parkinson's disease
  • psychological causes such as anxiety or depression
  • sarcoidosis (grainy lumps) affecting the salivary glands
  • infections that involve the salivary glands, such as mumps or HIV
  • Sjögren syndrome – a widespread inflammatory condition that also affects the salivary glands
  • liver cirrhosis
  • underdevelopment of the salivary glands (rare)
  • radiation therapy around the head and neck area
  • graft-versus-host disease following a bone marrow transplant.

Symptoms of dry mouth

When saliva is in short supply a number of problems can emerge, such as:

  • a need for frequent sips of water, particularly when speaking
  • more plaque forming on the teeth, leading to gingivitis and periodontal disease (affecting the tissue that supports the teeth)
  • tooth decay can increase
  • difficulty speaking and eating
  • bad breath (halitosis)
  • sores in and around the mouth
  • sore throat
  • stinging caused by strong tastes (such as minty, spicy or pungent foods)
  • wearing dentures becomes uncomfortable
  • oral thrush (a fungal infection) is more common
  • bacterial infections of the salivary glands occur more frequently
  • a burning sensation in the mouth (this is uncommon).

Self-care for dry mouth

Care for dry mouth

Your doctor may be able to prescribe a medicine to help stimulate saliva production. There are also a number of self-help measures you can try.

  • Sip water to temporarily moisten the mouth.
  • Avoid soft drinks and juices, which contain sugars and acids that are harmful to teeth. Even sugar-free soft drinks can be acidic and cause enamel erosion.
  • Suck sugar-free lollies to stimulate the production of saliva. Remember to limit their use, as too much of the sugar substitute can cause diarrhoea.
  • Chew sugar-free gum as a part of your daily oral care and to stimulate saliva production. Minty flavours may be too strong. If this is the case, try the milder fruity flavours.
  • Avoid alcohol, caffeine and smoking, all of which make a dry mouth worse.
  • Try over-the-counter saliva substitutes or oral moisturisers.

Care of your teeth and gums

Gingivitis and cavities are a greater problem for people with dry mouth, so good daily oral care is particularly important. It is also very important to see your dentist and dental hygienist regularly.

Learn more

Dry mouth NIH Seniors Health, USA, 2013
Dry mouth – range of resources MedlinePlus, USA, 2014

Credits: Reviewed by W Murray Thomson, Professor of Dental Epidemiology and Public Health, Department of Oral Sciences, University of Otago, September 2009. Reviewed By: Health Navigator