underactive thyroid
"When I was first diagnoised the doctor gave me levothyroxine, which uses lactose as a binder for the chemicals.  I had a huge reaction to the pill.  I felt like I wanted to get out of my skin,  Bad stuff.  So I started taking the dessicated thyroid, which was much better and I have been on it for many years. Recently, one doctor changed to liothyroine .  I got huge headaches that would not go away no matter what I took.  In two days of taking the pills, I stopped taking it on my own and switched back to the one that I had been on for so long.  The dosage now has to be increased, but at least I will not get the headaches."