... thyroid function. I read that my hair will fall out, although my hair is already thinning, and I am suffering from chronic fatique and I wonder how many of my symptoms are from the wrong thyroid medication and how much is from my having fibromyalsia. I have sweats during the day and night. I am really worried about the hair thing... I'm hoping that will stop and maybe regrow in the thinning area. I am just confused with the differant reports on this medication weather to take it or not. I have been taking synthroid for 15 years or so and my numbers with my recent blood work are very low and even the ones I don't understand (other than t3 and t4) are way off. Does it take long for any side effects to start and can they be reversed if I change back to synthroid?