I have been on it since 1989. I did not have any troubles at all until some yahoo Dr adjusted my dosage and increased a lot. I didn't notice anything for a little while but slowly I was becoming anxious, nervous and soon was not able to sleep. I would be wide awake until 3-4am and would get up a 530. I was also feeling so out of control and it was making me feel depressed. I went to a different Dr who wanted to put me on meds for depression and I told her to please look at my thyroid levels first. She did not think my symptoms had anything to do with my thyroid but tested it any way. Well my results came back revealing I was taking way too much...I think I was at .2 and she has decreased it mulitlple times and now I am at .137 I feel far better, am happy again and actually sleep.