Cellcept does have side effects and not everyone is able to tolerate the drug. However, the successes with Cellcept outnumber the failures (especially for treating Lupus Nephritis and preventing it from turning into chronic kidney failure). Cellcept has been found to have less toxic side effects than either azathioprine or cyclophosphamide.
I do hope that it works for you. Keep us posted on how you are doing with the drug!
Peace and Blessings