Levothyroxine is a thyroid medicine that replaces a hormone normally produced by your thyroid gland to regulate the bodys energy and metabolism. Levothyroxine is given when the thyroid does not produce enough of this hormone on its own.
Levothyroxine treats hypothyroidism (low thyroid hormone). It is also used to treat or prevent goiter (enlarged thyroid gland), which can be caused by hormone imbalances, radiation treatment, surgery, or cancer.