Thyroid hormones are sometimes prescribed to patients who have low thyroid levels due to a hypoactive thyroid gland. This medication may also be prescribed to patients who have thyroid cancer to stop abnormal growth of thyroid tissue.
This medication should only be prescribed to patients who have hypothyroidism or another thyroid disease that necessitates its use. It should not be prescribed as a treatment for obesity. Taking thyroid medication unnecessarily can cause thyroid toxicity, which can make people very ill; in addition, patients who take this medication along with amphetamines–i.e. weight loss pills–risk a potentially fatal drug interaction.