This extract from a 2000 booklet from Greenlane Hospital (now clinical centre) has some useful information on dry mouth, something we struggle with in so many ways after head and neck cancer. Some of you may have been given the book “Cooking Solutions for People with Dry Mouths” written by Greenlane Oral Health staff in 2000. The food advice and recipes are a bit out dated now and we have links to recipe books under Resources on this site. However, the information on dry mouth is useful so is reproduced here. 

Dry mouth/xerostomia

Dry mouth is caused by a number of conditions that affect the salivary glands in some way or another resulting in a diminished salivary flow. The severity of dry mouth differs greatly between individuals depending on which salivary glands are affected and how they are affected. Decrease in quality of saliva as well as quantity may occur in association with a dry mouth..


Saliva is a vital body fluid containing over 40 different enzymes and proteins as well as various buffers that play a variety of roles essential to oral health. Saliva is a natural cleansing agent of the teeth and gums and also lubricates the soft tissues of the mouth and throat enabling functions such as speaking, eating and swallowing to be performed easily.

The buffers contained in saliva help to soak up acids produced by bacteria that cause dental decay. Saliva contains immunoglobulins (part of the immune system) which counteract  infections and calcium and phosphates that help to remineralise teeth, making them less susceptible to dental decay.

 Causes of dry mouth

There are several causes but I have only included material relevant to head and neck cancer

Radiation therapy for head and neck cancer can result in damage to the salivary glands if the glands are within the radiotherapy fields. This damage can result in a diminished saliva flow.

 Some of the problems associated with dry mouth

A person suffering from a dry mouth may find that their lips become dry, sore and cracked. A common complaint is a dry and burning tongue. Swollen, tender salivary glands and angular cheilitis (cracking of the corners of the mouth) can also be unpleasant.

Taste sensation is commonly altered which in combination with the challenges of chewing and swallowing may result in a reduced interest in food. It is not uncommon for people with dry mouth to become malnourished and experience weight loss.

The soft tissues in the mouth may have a thinner layer of cells than normal and, therefore, may be more susceptible to damage. These soft tissues may also be more prone to infections such as candida (thrush).

Candida may present in a variety of forms but the most common appearance involves areas of the soft tissues within the mouth which have small white patches surrounded by red patches. Often if the white patches are rubbed off a red area will remain underneath which bleeds easily. Candidiasis may be associated with a tender/burning sensation, which can be aggravated by hot or spicy foods.

Denture wearing may become more difficult as a dry mouth significantly adds to the problem of retaining and eating with the dentures, which invariably become loose.

Of particular importance for people who have their own natural teeth is the problem of greatly increased dental decay.

Dental decay
Acids produced by bacteria that live in our mouths cause dental decay. Bacteria feed on the food and debris and then produce acids as waste products. These acids can dissolve our teeth through a process called demineralization . In people who have adequate saliva two key actions help prevent decay.

Firstly the cleaning action which removes the debris from the teeth and surfaces within the mouth. Secondly the minerals contained in saliva such as calcium and phosphate help to reverse the demineralisation (dissolving) of the teeth, ie they remineralise or strengthen the teeth. .

 There is a delicate balance between demineralisation and remineralisation within tooth structure and scales are greatly tipped towards demineralisation in people who have dry mouths due to lack of saliva. Careful attention to oral and tooth hygiene is important for everybody but it is mandatory in those who have xerostomia.

 Plaque control may be enhanced by regular use of antiseptic mouth rinses (eg chlorhexidine gluconate 0.2% (Brand names: Savacol by Colgate or Chlorhexidine Mouthwash by Delta West).

Pilocarpine is a useful stimulant of the salivary glands but has side effects and this is not a solution for everyone.

 Artificial saliva or lubricants may be used (eg Oral 7 gel, Xerostom gel). However, some people have  commented that these feel unpleasantly greasy and that price is off putting*. For people with dry mouths who wear dentures and find them difficult to retain, sticky products can be applied to the denture to help keep it in such as Poligrip and Fixydent.

The use of fluoride containing toothpaste is also recommended

Another very important consideration is that acidic drinks and foods will increase the rate of tooth decay in the mouth. All carbonated fizzy drinks (e.g. Coke, Fanta, lemonade, L&P etc) and commercially available fruit juices (e.g. Fresh Up, Just Juice etc) are very acidic. When coping with dry mouth it is common to want to sip drinks or suck sweets to reduce the “cotton wool” feeling. It is extremely important not to sip these acidic drinks but instead sip water.

There are also many sugar-free sweets and chewing gums which can be used to suck and these will not cause dental decay (in fact sugar free chewing gum may help stimulate saliva and hence reduce decay).

 Chewing of gum increases the salivary flow by at least three times in normal mouths and distributes saliva to the hard-to-reach areas of the mouth. The chewing of gum is, therefore, a very convenient way to help nature protect your teeth. The benefit comes from the chewing action which generates and distributes more saliva around the mouth. The best time to chew gum is immediately after a meal or snack so that the acid is neutralised as quickly as possible. To ensure that teeth obtain the full benefit, the gum should be chewed for 20 minutes (something most users do already).

If there is some part of the salivary gland still working, this may be stimulated by chewing gums or sucking sweets (sugar free).

In order to prevent dental decay, excellent oral hygiene must be maintained combined with chlorhexidine mouthwashes, fluoride toothpaste, and regular check ups with a dentist.

Since this handout was written there has been evidence that non-sugar sweetener Xylitol can prevent dental decay and this is now added to chewing gum and dry mouth products like Oral 7 and Biotene. Oral 7 and some other dry mouth products (gel, toothpaste, mouthwash) also contain enzymes to mimic natural saliva. Our group favours Oral 7 products as well as Xylimelts which can be purchased overseas or through Fishpond. These are round lozenges with gum on one side to adhere to your back teeth or gums. They release a nice tasting somewhat sticky moisture into your mouth for several hours. Good for the teeth too!

 *One aim of our charity is to provide some of the more expensive products to people who struggle to afford them. The arrival of the Chemist Warehouse in New Zealand has also given us access to lower prices.