Karen,
I have been on Cellcept for about a year. Initially it was prescribed at a relatively low dose for chronic pulmonary vasculitis, but my rheumy says it is a good drug to "layer" with Plaquenil for relief of my UCTD symptoms.
The only side effect I have is fatigue, though it is hard to know to what degree the fatigue is caused by Cellcept and what is just part of the autoimmune disease. As a precaution against infection I take low-dose antibiotics thre times a week, and I have blood drawn every six months to make sure the Cellcept is not affecting my white blood cell count. So far it has done a great job of keeping the lung inflammation under control.
I know not much is known about the effects of taking this long-term, but I would be quite ill without Cellcept so I try to focus on my health today instead of worrying about what may happen down the road.
Laura