I have been on Snythroid for 20 years. I had radiation treatment. I have experienced weight gain and most recently I think my hair is thinning. I take 1 0.15mg everyday except Sunday.I was reading a book that said the medication can cause loss of bone mass. I have been taking 1000 mg of Calcium a day. If you don't get those levels checked you will feel terrible! Take it from me! Thanks for sharing snythroid family