No, there isn't anything you take as a substitute
med. Many "side effects" of the med are actually those of hypothyroid
ism. Being hypo can cause some of the symptoms of RA, such as the joint/muscle aches, etc.
Some people do react to fillers/binders/dyes in the levo. Have you tried a different manufacturer? Each manufacturer uses different fillers/binders, so you might find one that doesn't have those effects.