Sjogren's syndrome is an autoimmune disease, characterized by the abnormal production of extra antibodies in the blood that are directed against various tissues of the body. This autoimmune illness is caused by inflammation in the glands of the body. Inflammation of the glands that produce tears leads to decreased water production for tears and eye dryness. Inflammation of the glands that produce the saliva in the mouth, which leads to mouth dryness.

Sjogren's syndrome that effects the gland inflammation (resulting in dryness of the eyes and mouth, etc.), but not associated with a connective tissue disease, is referred to as primary Sjogren's syndrome. Secondary Sjogren's syndrome involves not only gland inflammation, but is associated with a connective tissue disease, such as rheumatoid arthritis, systemic lupus erythematosus or scleroderma.

While the exact cause of Sjogren's syndrome is not known, there is growing scientific support for genetic factors. The illness is sometimes found in other family members. It is also found more commonly in families that have members with other autoimmune illnesses, such as systemic lupus erythematosus, autoimmune thyroid disease, juvenile diabetes, etc. 90% of Sjogren's syndrome patients are female.