Liothyronine is a man-made form of a hormone that is normally produced by your thyroid gland to regulate the body's energy and metabolism. Liothyronine is given when the thyroid does not produce enough of this hormone on its own.

Liothyronine treats hypothyroidism (low thyroid hormone). Liothyronine is also used to treat or prevent goiter (enlarged thyroid gland), and is also given as part of a medical tests for thyroid disorders.

Liothyronine should not be used to treat obesity or weight problems.