Hi - can anyone help me? I was diagnosed with underactive thyroid a year ago but felt absolutely fine. Doctors put me on thyroxine and ever since then I have terrible breathlessness on exertion and every day have a really rough bad inflamed throat. I have gone on and off the thyroxine because of this and when I go off it I get better and can breathe again but when I go back on it the same thing happens within hours. I used to be really fit, mountaineering and mountain biking, but now I feel like a cripple. The doctors tell me I have to be on thyroxine but it seems to be killing me. I have tried different brands, levothyroxine, tablets and liquid, and also natural thyroxine, Erfa, but they all affect me like this. So now I'm taking nothing but I'm scared as the doctors say I have to take it and it's dangerous not to. Has anyone got the same thing or any ideas of how I can get better?