That will depend on your body’s response to treatment. Although Levothyroxine is a more modern treatment, it only carries one of the two main thyroid hormones the thyroid gland produces, T4, also known as thyroxine. However, natural desiccated thyroid contains T3 (triiodothyronine), which is the active thyroid hormone used to control metabolism. Some patients who use Levothyroxine may have difficulty increasing their necessary T3 levels, leading them to switch to NDT. Most patients who previously used Levothyroxine saw their hypothyroidism symptoms and overall health massively improve after switching to natural desiccated thyroid medication.