The clinical term for dry mouth is xerostomia. Xerostomia is a common side effect of several medications and can also be caused by dehydration, chemotherapy, and many kinds of diseases; its cause may also be unidentifiable. Xerostomia can contribute to a variety of oral health issues, including dental cavities, demineralization of the teeth, yeast infection in the mouth, salivary-gland infection, an altered sense of taste or smell, bad breath, a burning or tingling sensation in the mouth, thick saliva, difficulty swallowing or chewing, sticky tongue or lips, fissures on the tongue, mouth soreness, sticky teeth, thirst, and sore or cracked lips and mouth.


Xerostomia can lead to tooth decay because saliva neutralizes acids that are formed when bacteria combines with residual sugars and starches in food debris. In the absence of sufficient amounts of saliva, it becomes more challenging to wash away acids and food debris. It is therefore far more important that people with dry mouths exercise excellent oral health care routines. Xerostomia can also affect a person’s ability to chew and swallow, as well as the ability to taste food and to digest, as saliva aids in these processes as well. While none of these things are necessarily life-threatening, they can greatly diminish quality of life and can contribute to larger, more systemic health concerns, including malnutrition and gastrointestinal distress and disorders.


Xerostomia may correlate with hyposalivation, or the reduced excretion of saliva, but it may not; sometimes, it is more related to a change in the consistency of the saliva, rather than a reduction in the amount. Xerostomia may also correlate with extraoral symptoms, or symptoms that occur outside of the mouth. These include dry eyes and the inability to cry, blurred vision, intolerance to light, a general burning sensation, changes in the voice, and dryness of systemic mucosa, possibly including the nose, throat, and genitals. If xerostomia is caused by an underlying illness, symptoms indicative of that illness may also occur.


Xerostomia is common upon waking, as the rate of salivary emission slows during sleep; this is the primary reason for bad breath upon waking. Xerostomia is also common when experiencing anxiety and when dehydrated. While elderly people experience higher rates of xerostomia, this is believed to have more correlation with the increased number of medications used by this population, many of which induce xerostomia. Medications that may induce xerostomia include psychoactive medications like antidepressants, blood pressure medications, anti-asthmatics, antihistamines, and diuretics.


Certain autoimmune disorders may also adversely affect the production of saliva. Sjögren’s syndrome and celiac disease are two common autoimmune disorders that can cause xerostomia, which can also be associated with hepatitis C and HIV. Radiation therapy in the area of the head and neck may also lead to xerostomia; dry mouth can also be caused by mouth breathing, alcohol use, smoking, recreational drug use, and certain hormone disorders.


To treat xerostomia, its cause must first be determined. In many cases, as it is often a symptom of underlying disorders or habits, xerostomia cannot be effectively treated, and instead, the goal is to prevent and treat the tooth decay it can cause, and to relieve the symptoms with saliva substitutes and saliva stimulators.