Hashi's is an auto
immune thyroid disease. when
you have Hashi's, your immune system is producing antibodies that attack the thyroid, eventually causing hypothyroidism.
"Thydroid deficiency" is also hypothyroidism, but from a cause other than auto
immune or an indeterminate cause.
There can be side effects
. By and large, it's well to
lerated since it's not a medicine, per se, but a replacement of the hormone your thyroid would produce if it could.