I have been on 188 of Tirosint from para thyroid tumor surgery and found cancer in my thyroid and had spread to some lymph nodes. I felt so much better after surgery until radiation. I have felt awful for two years now since the radiation. I told my MD last week I was going nuts and had every condition of over dosing or allergies to this drug. She said to get off of it for a week. It is amazing at how much better I feel. I am allergic to another drug I was on for thyroid replacement. I just had a DNA test of my P450 as it metabolizes drugs fast and I have over 80 medications I cannot take. I AM LOSING HAIR, from using Tirosint. And I must of been on too high of a dose. I am seeing a second ENDO Wed to pick her mind as my ENDO said he should drop my dose but did not think I could take it because of my P450. I get the results this week. My RN is on 137 of Tirosint and has lost half of her hair just as I have.