I have been on thyroid hormone for 45 yrs. I switched to a generic; levoxyl once for about 2 yrs and never want to do that again. I didn't attribute it to the switch because me loosing my mind didn't happen immediately. I couldn't understand what was wrong, I felt like my mind was not there, not me, crazy. Then read in a pill book that levoxyl had difference dosages of ingredients
then Synthroid did. I remember there being significant differences.