Dry mouth

Dry mouth

The facial nerve is responsible for facial movement and facial expression, but it also has a branch which stimulates saliva production called the chorda tympani. When the facial nerve is damaged, the chorda tympani can no longer stimulate the salivary glands to produce saliva.  This happens on the affected side only but people with facial palsy can experience problems with a dry mouth because there is not enough saliva being produced.

Saliva has the following functions:

  • It cleanses the mouth and in doing so protects teeth from plaque and tooth decay.  It also protects the gums and so prevents tooth loss.
  • It helps keep the mouth moist when speaking so the lips and tongue can glide easily over the teeth.
  • It helps us chew and prepare food ready for swallowing.  It acts like a binding agent helping to hold the food together into a ball which is passed to the back of the mouth where it is swallowed.
  • There are several enzymes in saliva that kick start the digestion of food.
  • Saliva can help us taste our food by carrying tiny food particles to the taste buds on the tongue.


The chorda tympani stimulates two of the three pairs of salivary glands to produce saliva.  These glands are named according to their position in the mouth – the submandibular gland (below the jaw), and the sublingual gland (under the tongue).

The medical term for a dry mouth is xerostomia (pronounced z-era-sto-mia).

What can help 

    • Brush your teeth regularly especially after eating to try and limit tooth decay.  You may also find that you have more food residue in your mouth after eating so brushing your teeth can help clear this residue and limit the build-up of bacteria in the mouth.
    • Regular dental check-ups will be essential, and your dentist may be able to prescribe you some products that can help with dry mouth.
    • Adding extra gravy, sauces, or butter to your food can help lubricate it so that chewing and swallowing your food is easier.
    • Regular sipping of water will help keep your mouth moist.  Avoid sugary drinks as these increase the risk of tooth decay.
    • Avoid becoming dehydrated so drink plenty of water and avoid drinks which contain caffeine and alcohol, as these can lead to dehydration.  Try decaffeinated tea and coffee.
    • Smoking can cause a dry mouth.
    • Certain medications, for example, some anti-depressants, can cause dry mouth so you may benefit from the products listed below.

You can obtain dry mouth products from your GP or dentist.  However, you can also buy these online without a prescription or sometimes over the counter at your local pharmacy.  The following products may be useful:

    • Artificial saliva in the form of gels, sprays, and chewing gum
    • Specialist toothpaste which does not contain a frothing agent, as this chemical can cause a dry mouth
    • Mouthwashes which do not contain alcohol

Common brands which are widely used in the health sector are BioXtra and Biotene.  For competitive prices consider using online retailers such as eBay or Amazon.

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Eating and drinking