Armour does not make a lot of money making their thyroid. They are a meat packing industry and use pig/cow thyroid. It does contain BOTH T3 and T4. The ratio is 80/20 or vice versa, not sure. Several years ago they were going to stop producing it and there was such an outcry, they reconsidered. You can go to the Armour site for more information.

There is quite a lot of money to be made in the synthetic drug market. The drug reps hate Armour and actually convince Drs. that it isn't any good.

In the past 15 years I have tried them all, synthetics that is, with not much luck. So I went to an endocronologist (sp) and he immediately put me on Armour.

BTW, some people cannot convert T4 to T3, so Synthroid won't work as well.

Good luck, hope it doesn't take you as long as it took me to figure it out.