Generic Name: levothyroxine

What is the most important information I should know about levothyroxine?

There are many other medicines that can affect levothyroxine. Tell your doctor about all the prescription and over-the-counter medications you use. This includes vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start using a new medication without telling your doctor.

What is levothyroxine?

Levothyroxine is a replacement for a hormone that is normally produced by your thyroid gland to regulate the body's energy and metabolism. Levothyroxine is given when the thyroid does not produce enough of this hormone on its own.

Levothyroxine treats hypothyroidism (low thyroid hormone). Levothyroxine is also used to treat or prevent goiter (enlarged thyroid gland), which can be caused by hormone imbalances, radiation treatment, surgery, or cancer.

Levothyroxine should not be used to treat obesity or weight problems.

Levothyroxine may also be used for purposes other than those listed in this medication guide.

What should I discuss with my healthcare provider before taking levothyroxine?

Since thyroid hormone occurs naturally in the body, almost anyone can take levothyroxine. You should not use this medication if you have had a heart attack, a thyroid disorder called thyrotoxicosis, or an adrenal gland problem that is not controlled by treatment.

Before taking this medication, tell your doctor if you have heart disease, coronary artery disease, anemia (lack of red blood cells), diabetes, problems with your pituitary or adrenal glands, or a history of blood clots. You may not be able to take levothyroxine, or you may need a dosage adjustment or special monitoring.

If you use insulin or take diabetes medicine by mouth, ask your doctor if your dose needs to be changed when you start using levothyroxine.

Tell your doctor if you become pregnant during treatment. You may need to increase your dose during pregnancy or if you plan to breast-feed.

In most cases, you will need to take levothyroxine for the rest of your life. Taking levothyroxine over long periods of time may cause bone loss, which can lead to osteoporosis. Talk with your doctor about how this could affect you.