s not usually the levothyroxine (the active ingredient in replacement thyroid hormone medications) that causes people to have trouble taking them. Typically, the problem is fillers, binders
or dyes. There are a number of manufacturers of
Levothyroxine and each one uses different ingredients, except for the levo, itself. For instance, Synthroid uses acacia and corn starch, either of which bothers many people... I didn't do well on Synthroid, but I do well on Levoxyl.