Causes of Dry Mouth

Causes of dry mouth (xerostomia) vary. Often, dry mouth results from blockage of or damage to the major salivary glands: the sublingual, submandibular, and parotid glands. Problems with the minor salivary glands can also cause xerostomia.

Medication and Dry Mouth

Dry mouth is not a natural consequence of aging. Often the causes of dry mouth can be traced to medication. Over 1,800 medications list dry mouth as a possible side effect. In general, we use more medications as we age, increasing the chances of xerostomia.

Pharmacological causes of dry mouth include many common medications:

antidepressants (especially tricyclic antidepressants)
anti-diarrhea medication
antihistamines
blood pressure medication
muscle relaxants
Parkinson's Disease medications
urinary incontinence medication.

Chemotherapy and Radiation Therapy

Chemotherapy drugs reduce salivary gland production and thicken saliva. The salivary glands should begin to function normally once chemotherapy treatment ends.

Radiation therapy for head and neck cancers can also damage the salivary glands. The damage is usually temporary, but can be permanent.

Infection of Salivary Glands

Salivary gland infections are common causes of dry mouth. When a bacterial or viral outbreak infects a salivary gland, the condition is called sialadenitis. Bacterial causes of dry mouth include Staphylococcus, Streptococcus, and E. coli. If a salivary gland is blocked or obstructed, bacteria accumulate in the gland.

Viral salivary gland infections are mainly seen in children who have not received the full program of vaccinations. People with suppressed immune systems, including people with HIV, are also susceptible to salivary gland viral infections.

Mumps ca infect the parotid gland, causing xerostomia. The mumps virus that affects the parotid gland is called paramyxovirus. A type of herpes virus known as cytomegalovirus can also affect the parotid gland and the other major salivary glands.

Salivary Stones and Xerostomia

Salivary stones (sialothiasis) can block saliva flow. Salivary stones are mineral deposits that build up in a salivary gland. Salivary stones are more common in the submandibular glands than the sublingual or parotid glands.

Mucoceles and Ranulas

Damage to a minor salivary gland in the lower lip area causes swelling of the lower lip, a condition known as a mucocele. Ranulas are mucus cysts that occur in the sublingual and submandibular glands and are causes of dry mouth. Medical causes of ranulas include:

Alzheimer's disease
anxiety
depression
diabetes mellitus
Sjogren's syndrome
stroke
thyroid dysfunction.

Dry Mouth and Nerve Damage

An injury or surgical trauma can damage the nerves responsible for salivary gland stimulation. The resulting lack of salivary gland stimulation can cause dry mouth.

Salivary Gland Tumors

Salivary gland tumors are abnormal growths that can cause dry mouth. Benign salivary tumors are more common than malignant growths, but both can be causes of dry mouth, and both require special treatment.