I took synthroid for several years and became progressively more arthritic, with horrendous tooth problems and congestive heart failure. My doctor switched me to the lowest possible dose of generic levothyroxine for nearly two years, and during that time, I progressively felt better. Then they stopped making the generic 25 mcg, so I was switched to levoxyl 50 mcg (was told to split in half). Since then, the symptoms of aching joints and emotional rollercoastering has returned, along with sleep disruption and heart trouble. There is NO DOUBT that these thyroid hormones cause serious problems in many people. I am now trying accupressure to stimulate the gland, and slowly withdrawing the levoxyl. Already feel much better!!!