Hey there
well I don't know about you but I find sex very painful at times with lupus, I can't get anything up there without pain so I don't like or use tampons.
I haven't heard from my doc that tampons are a no no with lupus, although for me too i'm so heavy with my period that a tampon wouldn't be enough anyway.
I would ask your doc or gyno why it is bad, it could just be that it's because of the pain most people have using them with lupus or fibro.
Take care