Both levothyroxine and liothyronine (Cytomel) are synthetic (lab-made) thyroid hormone replacement medications. Levothyroxine is T4, which is a nonactive thyroid hormone. It gets turned into T3, the active form of the thyroid hormone, once it's in the body. Liothyronine (Cytomel) itself is T3. Speak with your prescriber to learn more about comparing between levothyroxine and liothyronine (Cytomel)

Liothyronine (Cytomel) is a lab-made version of the T3 thyroid hormone that's normally made by your thyroid gland. It's the active form of the thyroid hormone that helps regulate many functions of the body.

There isn't much evidence showing that taking levothyroxine and liothyronine (Cytomel) together is beneficial, so clinical guidelines typically don't recommend43030-7/fulltext#:~:text=RECOMMENDATION%2022.2%20The-,evidence%20does%20not%20support,-using%20L%2Dthyroxine) taking them together. But some studies found that some people have preferred this combination and some people might need both medications if one isn't enough to bring thyroid hormone levels back to normal. Speak with your prescriber if taking levothyroxine and liothyronine (Cytomel) together is appropriate for you.