Side effect of anti thyroid drug?

Lots to know. Usual GI upset, possible rash, but the ones you need to know about are the rare idisyncratic reaction you can get that may cause liver failure or bone marrow suppression. There are rare occurrances and as long as you stop med. Immediately if symptoms occur, you are safe. Discontinue med if you develop yellow eyes or unexplained fever and call your doc. It may be unrelated but you will be safer.