Hashimoto's & Hyperthyroidism Does Hashimoto's Disease cause hyperthyroid symptoms? There may not be much in the medical journals on this yet but apparently Hashimoto's can cause hyperthyroid symptoms at first. I know I experienced more hyperthyroid symptoms at first than hypothyroidism. My early symptoms that I recall included intense nervousness as if my nervous system was on high alert but not accompanied by any stressful events or emotions. I had a tremor for probably at least 2-3 months until I started treatment and still had transient tremors for a few years afterward. I had a high energy level & continually stayed busy. I also had a goiter which eventually went away over a period of a few years. I noticed I was beginning to have a decline in cognitive abilities. Other than this I can't recall any additional symptoms. I didn't gain weight at that time. I wasn't tired. Actually I experience some transient fatigue now. I received an email from another person who experienced hyperthyroid symptoms. Hi! I read your information on Hashimoto's Disease. I was diagnosed with Hashimoto's Disease in December of 2000. But, I was also diagnosed as HyperThyroid not underactive (hypo) that normally is Hashimoto's Disease. So, I am backwards then anyone else. I have read so much about the Thyroid and it gets so confusing. Overactive (hyper) me - normally goes with Graves Disease but not me, I have got Hashimoto's Disease. I am so grumpy all the time with gaining 30 pounds so far. I am normally 125 - 130 and I am 150 now. IT's so upsetting to me. I am so tired all the time and I definately have the Couch Potato Syndrome that you mentioned. Anyways, just wanted to write someone who is dealing with thyroid problems. Anything else you can say about it is welcomed! Thanks so much! Tracy back