Sjogren's Syndrome

My wife has been diagnosed with Sjogren's Syndrome. Her only sympton is the extreme dry mouth. Her Dr. prescribed Prednisone for her. I have read that it does not do a very good job. Gamma-linolenic acid, which is a plant derivitive has shown the best results. Do you know anything about this, and is it available without a prescription?

Sjogren's syndrome is an autoimmune disorder (one where the immune system attacks the body's own cells) affecting the salivary and lacrimal (tear) glands, often associated with Rheumatoid Arthritis.
Evening Primrose Oil is rich in gamma-linolenic acid, has shown to be effective in autoimmune disorders, and is recommended in Sjogren's Syndrome. It is easily available in capsule form in health food stores.