Synthroid (levothyroxine) is a replacement for a hormone that is normally produced by the thyroid gland to regulate the body’s energy and metabolism.
Doctors prescribe Synthroid to patients whose thyroids do not produce enough of the hormone on its own. Synthroid is the most-prescribed thyroid medication for the past 42 years.
Synthroid also may help decrease the size of enlarged thyroid glands (known as goiter) and treat thyroid cancer.
Synthroid has been linked to adverse side effects, including severe headache in children, skin rash or hives.