Cytomel is the name brand for synthetic T3 med.
Synthroid is a name brand for synthetic T4 med.
Some people do better taking the name brands; however, some of us do fine on the generics. Still others do better on T4/T3 combo, dessicated, such as Armour, NatureThroid, etc. I'm on both T3 and T4 med, both generic and doing well.
Do you have symptoms? If so, what are they? What are your latest test results? Can you post them along with the lab's reference ranges?