In the treatment of hypothyroidism, thyroxine is preferred over liothyronine because of thyroxine:

Liothyronine (T3) as compared to thyroxine (T4) is: Fast acting More potent Short half-life An indication of liothyronine includes myxedema coma and for most of the indications, thyroxine is used because it has a long half-life thus can be used less frequently than T3.