Causes and complications of dry mouth

The subjective feeling of dry mouth (xerostomia) is a relatively common condition that may or may not occur in the context of salivary gland hypofunction (an objective reduction in the quantity and the quality of saliva).

Many physiological and pathological conditions and drugs can cause salivary gland hypofunction or dry mouth. Common causes of dry mouth include:

• dehydration
• alcohol
• anxiety
• mouth breathing
• drugs (see Drugs frequently associated with dry mouth).

If common causes have been excluded, investigate for less common medical conditions associated with dry mouth (eg Sjögren syndrome).

Dry mouth is a debilitating adverse effect of head and neck radiotherapy, with the degree of salivary flow reduction dependent on the dose and region of the radiation (see also Head and neck radiotherapy: dental considerations).

Chronic dry mouth can have a profound effect on the oral environment and can contribute to:

• tooth decay (dental caries) and erosion
• periodontal disease (eg gingivitis, periodontitis)
• oral mucosal disease
• oral candidiasis
• difficulty with the retention of dentures
• difficulty with chewing, swallowing and speech
• altered sense of taste.