underactive thyroid
"i have been on levothyroxine for several years.  my dosage has been adjusted several times.  I had a terrible experience with the higher dosage...migraine headaches, palputations, night sweats.  come to find out that i was actually having a reaction to the dye in the higher dosage.  Once that was figured out my doctor put me back on the 50 mcg and had me take two pills each day.  so far its been great."