Here in the U.S., thyroid replacement medication is marketed under a brand named Synthroid, but still a variant of thyroxine. I've taken 75mcg daily of Synthroid for over 20 years and also take 400 mg of natural Echinacea purpurea daily. Other than an uncontrollable tic, walking pigeon toed and sudden desire for Ben & Jerry's Chocolate Chip Cookie Dough ice cream, no noticeable side affects.