Thyroxines are used to treat hypothyroidism, or a condition of low thyroid hormone levels in the body. They also have other uses, such as managing certain types of thyroid cancer after thyroid surgery. Thyroxines work by replacing or supplementing the thyroid hormone that your body normally produces, helping to regulate your metabolism and energy levels. These medications come in different forms, including oral pills and liquid solutions. Examples include levothyroxine (Synthroid, Unithroid, Levoxyl). You can choose the form that best fits your needs.