Is Behcet's Disease Fatal?

Behcet' s disease is characterized by inflammation of the
blood vessels of entire body. Common symptoms of this disease are sores in mouth and on genital organs, Sores on other areas of skin, swelling of eye leading to blindness, and swelling and stiffness of joints. This disease can also affect brain leading to stroke, digestive system and vascular system causing blood clots and aneurysm.  
Exact cause of Behcet' s disease is not known. There are some researcher who support idea of autoimmune disease, genetical factors, environmental factors and bacterial or viral infection.
There are no proper treatments available for this disorder. Only symptomatic treatments are available. This disease is generally not fatal as symptoms come and go but if eye symptoms not treated can cause blindness.

Only if it kills you.   (You should be leery getting medical advice from people who are not doctors of medicine.)