I know how you feel (being scared about being without a thyroid). I wrestled with that one, too. And, I’m still nervous about it from time to time, even though I made the decision to go with RAI. I took PTU after being diagnosed. It is pretty much the same kind of medicine as Tapazole, I think. You could probably get a better answer from a pharmacist than from any one of us. The difference that I’ve heard about is that with PTU you have to take more frequent doses of medicine. I was on a strict, every eight hour schedule of two to three pills each time. It may give better flexibility with dosages, but it was like being on a leash. I found that if I spaced them correctly, I felt better than when I did not due to activities, etc. Anyway, the side effects of PTU are pretty much the same as Tapazole: you have to have your bloodwork done periodically, and if you get a high fever and sore throat you have to discontinue it IMMEDIATELY and call your doctor. It can supress your bone marrow. Permanently, in rare cases. Also, you are not supposed to get around people who have had flu shots, polio vaccinations or other “live” vaccines — or you might come down with the disease in question. I had to get my flu shot this year in partial dosages, because of PTU.
The only other “option” is surgery, which doctors do not prefer because there are dangers involved that are not involved with the RAI. There are instances where they cannot do RAI, pregnancy or severe Graves eye problems, but barring those situations, they prefer RAI. There are no detrimental aspects to the treatment, its been used for fifty years without subsequent problems showing up.