Euthyrox 150 mcgs 50 tab tablets contain the active ingredient Levothyroxine, which is a synthetic form of the naturally occurring thyroid hormone, thyroxine (T4). It is used to replace thyroxine when the body does not produce enough of this hormone. It is used for the treatment of hypothyroidism and to help promote weight loss in people with obesity. It has also been used to help treat polycystic ovarian syndrome, fibromylagia, depression, congestive heart failure, and some other medical conditions. It regulates metabolic rate and is necessary for normal growth and development.