What is the most common cause of xerostomia?

Xerostomia is the medical term for a dry mouth. It happens when the salivary glands produce less than optimal amounts of saliva. Aging that leads to decreased salivary gland production, dehydration (not drinking enough fluids) and anxiety are the most common causes. Dry mouth is a side effect of many medications, and it may result from autoimmune diseases like Sjogren’s syndrome. Radiation treatments to the head and neck can damage the salivary glands.