I have bought 3 bottles of Thyrovanz. I have taken 2 of the bottles. I have been on thyroid medication for quite a few years. When I went in for my 6 month check up, the doctor took blood to check my thyroid. It had gotten so low she changed my medication dosage. I haven't even opened the 3rd bottle of Thyrovanz, because I didn't want to take the chance of my thyroid count getting too low. But I recommend Thyrovanz, it works eell.