Not Recommended. The main reason physicians will tell you not to use it, it that since 2002, the american association of clinical endocrinologists does not recommend the use of desiccated thyroid for thyroid replacement therapy for hypothyroidism (baskin, 2002). In general, desiccated thyroid hormone, does not provide a uniform amounts of levothyroxine.
Amour is just fine. Armour thyroid is one of the better medications for hypothyroidism, because it mimics natural thyroid hormone levels way better than synthroid (thyroxine) does. The company that made Armour did at one point change the formulation; people had to chew it to get absorption, but since then it has changed again, and the current formulation is just fine. Iron and magnesium can inhibit absorption. So take it alone.