When Plaquenil with accompanying Prednisone (like Bill says, lower dosage, longer term) doesn't do the trick, the next level of medications most commonly used are Imuran, Cellcept, and MTX.
It is not known which of these 3 will help any individual patient or why, it's trial and error to see which might work for you. (For instance, Imuran did nothing for me, Cellcept put me into remission, while other patients have different results.) These medications are used in conjunction with Plaquenil and Prednisone, not in place of them.
Then there is a 3rd level of treatment, Benylsta and IvIG. I don't know as much about
when they are used, but I think it's after Imuran/Cellcept/MTX have been used to no effect.
One thing I recommend, which may not be helpful in your area, is to check out
www.lupus.org, and find the closest local chapter. The Drs who are active on the local chapter's advisory board are often the most Lupus knowledgeable in the area. If you are outside the US, try to find the Lupus organization that covers your area.
Best wishes,