I have only been taking Levoxyl for about two weeks, following RAI treatment in May. I'm on 100 mcg. I had gone from being hyperthyroid to hypothyroid - with walking or much movement, it felt like the muscles in my back were being stretched from each side and held up to a sunlamp to the burning point. I was also having upper back pain and a stiff neck.
After a little over a week of taking Levoxyl, the stiff neck is still there, but the back pain has eased off a little. There is just one spot that feels like a sunburn from the inside out. The biggest problem I'm having is with the sodium content - it feels like I've eaten an entire shaker of salt. I suspect that my blood pressure is increasing on this med. I'm noticing restless leg syndrome and while I always have tinnitus, it has worsened in the past week. I'm also noticing fluid retention all over, puffy eyes, puffy fingers, and calves. I'm also having more headaches.
On the plus side, the unbearable muscle pain has eased up some, as I mentioned. I'm less depressed. It's too soon to tell about weight but I think I've stopped gaining for the moment.