Sjögren syndrome is a complex disorder in which exocrine organs are infiltrated by lymphocytes. It is characterized by sicca symptoms and is frequently associated with systemic lupus erythematosus, rheumatoid arthritis, or scleroderma.

The estimated incidence of Sjögren syndrome is 0.1% to 3%, with the wide estimated range being the result of absence of uniform diagnostic criteria. Females are affected more often than males by a 9:1 ratio.

The etiology of Sjögren syndrome is not truly known. Theoretically there appear to be interactions between major histocompatibility complex (MHC) genetic factors and non-MHC genetic factors, along with still-undelineated environmental factors. Sex hormones are theorized to play a role because of the overwhelming tendency of this disease to affect women.