J.W.
Of course - it is prescription as well, and has not just the T4 but like Cytomel, also has the T3 which is what the cells actually use (has to convert T4 to T3. In addition, it also has some T1 and T2. Scientists used to think the body did not use the other forms of Thyroid - T1 and T2 but now they know something at least about T2 and YES - the body uses that as well.
Both my children who need both T3 and T4 (i.e. the equivalent of both prescriptions - Cytomel & Levothyroxine) take the prescription dessicated thyroid instead. Many who still felt fatigued and symptomatic on just T4 do much better on the combination.
Of course, since most dessicated thyroid is obtained from pigs, if a person is allergic to pork, they might not be able to take it. Also, although Armour brand of Thyroid does not have dairy in it, watch out - many of the generics have dairy fillers, and if you are allergic to casein, those may be contra-indicated.