Dry mouth [xerostomia] may result from one of a number of causes. The mouth is supplied with saliva by pairs of major salivary glands and hundreds of tiny minor salivary glands scattered all over the lining of the mouth. There may be damage to or disease of these salivary glands. Alternatively the glands themselves may be normal, but the rate at which saliva is produced is low. Dry mouth may also occur with diabetes, stress or depression. It may follow radiotherapy to the head and neck. The most common reason for a dry mouth is as a side-effect of prescribed medicines.
The main disease causing a dry mouth is Sjögren’s syndrome (pronounced ‘show-grunz’). This condition can either occur by itself, when it is known as primary Sjögren’s syndrome, or in secondary form alongside conditions such as rheumatoid arthritis. Because it will affect all salivary glands, both major and minor, the whole mouth will be drier. In both conditions, there is associated dryness of the eyes, and there may be other symptoms such as tiredness. Both types of Sjögren’s syndrome can be investigated with blood tests, and sometimes a small biopsy of the minor salivary glands in the lower lip.
The most commonly prescribed medicines that cause a dry mouth are tablets used for treatment of blood pressure. The next most common are those used to treat anxiety and depression, and antihistamines taken for hay fever and treatment of allergies. In younger people, inhalers used to treat asthma may also cause a dry mouth.
A dry mouth is often quite uncomfortable and may make eating difficult. One of the functions of saliva is to help prevent tooth decay and gum disease so if you have a dry mouth you will be more at risk of getting these diseases. It is especially important for sufferers:
If the sufferer wears dentures there is an increased risk of developing thrush in the mouth. To avoid this it is important to take the dentures out at night and clean them regularly. It may occasionally be necessary for the dentist or doctor to prescribe a medication to treat or prevent oral thrush.
If there is some salivary gland function, then the flow of saliva can be increased by chewing gum or sucking a sweet - they should be sugar free.
Regular sips of water throughout the day may help to keep the mouth comfortable and it is helpful to take sips of water while eating.
There are a number of saliva substitutes that may be bought from a pharmacy or prescribed by a dentist or doctor. Other saliva stimulants are available; these are mainly sprays, gels, tablets or pastilles to suck.
There is a medication available (pilocarpine) which can stimulate salivary glands that still have some saliva-producing ability left. A doctor or hospital specialist can prescribe this. However, it has a number of side-effects which some people may find unpleasant.
If in doubt, consult a dentist or doctor.