I had RAI treatment 3 years ago, with very minimal side effects, much like those stated above. However, it has been difficult for my doctor to find that "sweet spot" continually increasing my synthroid (I’m up to 225mcg which is fairly high). I’ve suffered with symptoms of hypotyroidism since about 8 months to a year after my RAI, with no real relief, and gained a lot of weight during year 2. I may very well be an unusual case, however, my point for telling you is this … at times I regret the RAI, only in that I have taken away any other treatment options for myself forever. I rushed to RAI soon after my diagnosis due to outside issues, but now wish that I had explored medication therapy more first. Just one opinion …