Levothyroxine (Synthroid) is an oral medication used to treat hypothyroidism (underactive thyroid). It's a lab-made version of the T4 thyroid hormone. It's important to stick to the same levothyroxine ...

Levothyroxine is a generic drug prescribed for hypothyroidism (low thyroid hormone levels) and certain thyroid cancers. As with other drugs, levothyroxine can cause side effects, such as hair loss ...