underactive thyroid
"I have been on Levothyroxin for four years.  I have no thyroid.  I have gained 60 pounds.  I am angry about the weight gain.  I have absolutely no energy when I used to have too much.  The major problem that I found with this drug is that it gives me bad heart burn.  I also have heart palpitations.  The doctor claims my levels are where they should be and refuse to switch me to anything else."