Dry mouth

Saliva

Saliva, or spit, is the fluid produced by the salivary glands, which are situated around the jaw and under the tongue. Saliva keeps the mouth clean and helps to prevent infection. It also protects your teeth, as a lack of saliva can increase your risk of developing tooth decay or gum disease.

When you eat, more saliva is produced to moisten the food, which makes it easier to chew and swallow, as well as beginning the process of digestion. A lack of saliva can change the taste of the food you eat and may also mean that you cannot swallow food so well.

Radiotherapy treatment to the head and neck, or mouth, can affect the salivary glands, so that less saliva is produced. The glands may recover over time (sometimes this takes several months), but for some people the dry mouth may be permanent.

How your doctor can help

Drugs to stimulate saliva It is important to tell your doctor if you have a dry mouth, as they may be able to prescribe medicines to help. Pilocarpine (Salagen®) is usually used. Sometimes a drug called bethanechol may be used instead of pilocarpine, although it's not licensed to treat dry mouth.

These drugs stimulate the salivary glands to produce saliva and will only work if the damage to the glands is temporary or partial. Two or three months of continuous treatment with pilocarpine may be needed before it is effective in stimulating temporarily damaged salivary glands to work again.

Unfortunately, pilocarpine does not work if the damage to the glands is permanent.

Like many drugs, pilocarpine has side effects. It can cause sweats, nausea and vomiting.

Artificial saliva

Artificial saliva products can also be helpful for moistening the mouth. As their effect may last only for a short time, it is best to use them just before meals and at night to prevent the dryness from disturbing your sleep. Several brands are available and they come in the form of a gel, spray, pastille or tablet. You may find it helpful to try more than one form of artificial saliva brand to find out which one suits you best.

How you can help yourself

Keeping your mouth clean As saliva helps to keep your mouth clean, it is important to brush your teeth with a soft toothbrush after each meal, and to use mouthwashes regularly. However, mouthwashes containing detergents or alcohol should be avoided as they can dry and irritate the lining of the mouth. Your doctor or nurse will be able to advise you about the best mouthwash to use. Regular dental check-ups are essential too, as the risk of developing tooth decay is increased by a lack of saliva.

Encouraging saliva production If your salivary glands are still able to produce some saliva, sucking sugar-free sweets or chewing sugar-free gum can encourage saliva production. Pineapple chunks, ice cubes, frozen tonic water, yoghurt and buttermilk can also be helpful, although some people find that very cold foods or drinks may be too uncomfortable to use.

Keeping your mouth moist To keep your mouth moist you can drink sips of water or sugar-free fizzy drinks regularly throughout the day. Rinsing your mouth with a little vegetable oil (about a teaspoonful), or a small amount of softened butter or margarine can also help, especially at night.

Cut down or avoid substances that can dry the mouth These include alcohol, caffeine and cigarettes. Some prescribed medicines can also cause a dry mouth and it can be helpful to ask your doctor or nurse to identify these, as it may be possible to reduce the dosage or change the drug.

It may also be helpful to try acupuncture as this may sometimes increase the amount of saliva that is produced.

Boosting appetite Many people can lose their appetite| due to a dry mouth, or may find that foods taste different, which can cause eating difficulties. Here are some tips that can make food more palatable:

• make sure you drink fluid with meals
• include plenty of sauces and gravy with meals
• include foods with a high fluid content, such as jelly, puréed fruits and soft puddings in your diet
• avoid dry and 'thick' foods such as biscuits, crackers and dry snacks.

References

This section has been compiled using information from a number of reliable sources including:

• Oxford Textbook of Oncology (2nd edition). Souhami et al. Oxford University Press, 2002.
• Cancer and Its Management (5th edition). Souhami and Tobias. Oxford Blackwell Scientific Publications, 2005.
• Oxford Textbook of Palliative Medicine (3rd edition). Doyle et al. Oxford University Press, 2005.

For further references, please see the general bibliography|.