What is levothyroxine?

Here are some examples of levothyroxine. For each item in the list, the generic name is first, followed by any brand names.

• levothyroxine (T4) (Levothroid, Levoxyl, Synthroid, Tirosint, Unithroid)

This is not a complete list of medicines for low thyroid.

Levothyroxine replaces a hormone that the thyroid gland usually makes.

Cautions for levothyroxine include the following:

• If your dose of medicine is too high, you may feel nervous, have irregular heartbeats, or have problems sleeping. You may also have tremors (shaking). And over time, you may develop osteoporosis. If you have heart disease, too much medicine can cause pain (angina) and irregular heartbeats.
• If your dose is too low, you may have symptoms of hypothyroidism. These include constipation, confusion, feeling sluggish or cold, and gaining weight.

Levothyroxine is used to treat hypothyroidism. It's also used to treat an enlarged thyroid gland (goiter). You may use this medicine if your thyroid gland doesn't make enough thyroid hormone. Your body needs this hormone to work as it should.