The drug is available under the brand names Levothroid, Levoxyl, Levo-T, Synthroid, Tirosint, and Unithroid.
Thyroid hormones affect the metabolism of protein, fats, and carbohydrates. They also affect a person's growth and development.
If untreated, hypothyroidism can lead to poor growth, slow speech, loss of energy, weight gain, hair loss, dry skin, and increased sensitivity to cold temperatures.
Levothyroxine can help reverse these symptoms. The drug can also help treat the congenital form of hypothyroidism, as well as an enlarged thyroid gland (goiter) and thyroid cancer.
Levothyroxine has been available in the United States since the 1950s, but the Food and Drug Administration (FDA) didn't approve it until 2000.
