I am 56 years old and was healthy. I started Levothyroxine 50mcg and shortly afterwards was sick and very anxious. Within a few days I had a heart attack. I told the cardiologist I had just started Levothyroxine but she didn't say anything about it. They don't know why I had a heart attack but ever since I have been having palpitations and feeling anxious, depressed and with tremors. I rang my doctor for an appointment but couldn't get one. A doctor rang me and prescribed valium over the phone. My palpitations were so bad I had to call an ambulance but they said I was ok. I am still waiting for tests due to long waiting lists. I was telephoned from the doctor surgery yesterday who said I need to reduce my dose to 25mcg. My TSH was high at the start but my throid was within normal limits. I spoke to a naturopath yesterday who immediately said that I should have been started on 25mcg and not 50mcg. I am now doing some research on overdosing as I want to know why I had a heart attack as its worrying me. Today my tremors and anxious feeling has stopped. Has anyone else had this problem? My friend also had heart problems but I left it too long and it turned into a heart attack.