Dry mouth, or xerostomia, is a dryness of mucous membranes of the mouth that occurs when saliva production is inadequate or absent. This symptom is often accompanied by taste alterations or loss of appetite.
The major cause of inadequate saliva production is exposure of the salivary glands to radiation. The dose of radiation, the duration of treatment, and the size of the treatment field determine the degree and duration of xerostomia. Decreased saliva begins seven to ten days after the start of therapy, reaches its peak within two to three weeks, and continues for a period after therapy. The absence or inadequate production of saliva may be a permanent side effect of radiation therapy. Even if the disruption is temporary, production may not reach a normal level for six months to a year.
Other causes of inadequate saliva production include the presence of a tumor in the salivary region, dehydration, administration of antihistamines, narcotics, or drugs containing atropine, infections inside the mouth, and the use of tobacco and alcohol.
Inadequate saliva results in inadequate digestion of starches, risk of irritation or damage to the mucous membranes, acceleration of the development of mouth sores, decreased taste acuity (since food must be in solution to be tasted), difficulty in chewing solid food, increased potential for the development of dental caries and oral infections, and difficulty in speaking, since dryness of the membranes hampers the usual speech patterns.
If saliva production is severely impaired or ceases permanently, artificial saliva, available by prescription, may be necessary. For temporary or moderate reduction of saliva, simpler measures may be sufficient.
The person should:
- Drink water and other nonirritating liquids such as apple juice, grape juice, or fruit ades several times each hour.
- Use a thermos with a special spout for sipping if a convenient water source is not available.
- Lubricate the lips with K-Y Jelly, cocoa butter, or a lip balm (such as Chap Stick).
- Suck on smooth, flat, sugarless candy or lozenges. Sour substances usually stimulate saliva production.
- Humidify the air with a pan of water near the source of heat, a cold-water vaporizer, or a humidifier installed as part of the central heating system.
- Since saliva digests starch and helps prevent dental caries, people with inadequate saliva should avoid starchy foods and take special precautions to avoid caries. The oncologist can prescribe a fluoride gel and special apparatus for using it which is very effective in preventing dental caries. In addition, the person should take the special precautions for brushing the teeth and rinsing the mouth that are listed in the section on mouth sores.
To summarize, tobacco and alcohol should be avoided, as well as foods that are highly spiced, carbonated, very hot or very cold, difficult to chew, or acidic (such as citrus fruits and juices). If the person has difficulty in swallowing, liquids and semi liquids such as gravies, sauces, or mayonnaise can be added to food. Food should be thoroughly cooked and cut into small pieces, or pureed if necessary.