Dry mouth or xerostomia refers to any condition in which your mouth is unusually dry. Most often, dry mouth is the result of a decrease in saliva produced by the salivary glands in your mouth, and it's frequently a side effect of medication. Less often, dry mouth may be caused by a condition that directly affects the salivary glands.
Xerostomia is a very common symptom. A conservative estimate of prevalence is about 20% in the general population, with increased prevalence in females (up to 30%) and the elderly (up to 50%). Xerophthalmia usually affects children under nine years old and "accounts for 20,000-100,000 new cases of childhood blindness each year in the developing countries." The disease is largely found in developing countries like many of those in Africa and Southern Asia. The condition is not congenital and develops over the course of a few months as the lacrimal glands fail to produce tears.
Dry mouth has numerous causes. Hundreds of medications, including many over-the-counter drugs, produce dry mouth as a side effect. Some of them are antianxiety drugs, anti-depressants, antihistamines, decongestants, muscle relaxants and pain medications. Chemotherapy drugs can change the nature of saliva and the amount produced. This may be temporary, with normal salivary flow returning after treatment has been completed. An injury or surgery that causes nerve damage to your head and neck area can result in dry mouth. Dry mouth can be a consequence of certain health conditions, including the autoimmune disease Sjogren's syndrome or HIV/AIDS. Smoking or chewing tobacco can increase dry mouth symptoms. Methamphetamine use can cause severe dry mouth and damage to teeth, a condition also known as "meth mouth."
Treatment depends on the cause of your dry mouth. Changing the medications that cause dry mouth. Over-the-counter mouth rinses, artificial saliva or moisturizers are recommended to lubricate your mouth. Pilocarpine (Salagen) or cevimeline (Evoxac) are prescribed to stimulate saliva production.