Synthyroid for low thyroid seemed to give me an internal tremor when taken in a dose that brought my levels up to what the doctor said it should be. I told him I couldn't take that much and I would rather be alittle low. Synthyroid also caused lumps to develop in chest...which was not great. When I found out there was a natural precription called Armour Thyroid (animal thyroid dried/ ground and made into a pill form.)..I made the switch and immediately felt better. I can't take as much of it as they want me to either (taking the lowest dose available 3 mornings a week to get by). Too much of it will make tremor also for me. Everybody is different ...what works well for one person will go against someone else's metabolism. I try to stay away from doctors and do herbs as much as possible to keep well. Hope this helps.