Levothyroxine general information
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 may also be used for other purposes not listed in this medication guide.
Levothyroxine dosage and administration
Take levothyroxine exactly as your doctor has prescribed it for you. Do not use more of the medication than recommended. Do not take levothyroxine for longer than your doctor has prescribed.
Your doctor may occasionally change your dose to make sure you get the best results from this medication.
It is very important to take levothyroxine with a full glass (8 ounces) of water. The levothyroxine tablet can dissolve very quickly and swell in the throat, possibly causing choking or gagging. Take this medicine on an empty stomach, 30 minutes before eating. Levothyroxine is usually taken in the morning. Follow your doctor's dosing instructions and try to take this medication at the same time each day.
It may take several weeks before your body starts to respond to this medication. Do not stop taking this medication suddenly. Even if you feel well, you may still need to take this medicine every day for the rest of your life to replace the thyroid hormone your body cannot produce.
For replacing the thyroid hormone:
- Adults and teenagers—At first, 0.0125 to 0.05 milligrams (mg) once a day. Then, your doctor may increase your dose a little at a time to 0.075 to 0.125 mg a day. The dose is usually no higher than 0.15 mg once a day.
- Children less than 6 months of age—The dose is based on body weight and must be determined by your doctor. The usual dose is 0.025 to 0.05 mg once a day.
- Children 6 months to 12 months of age—The dose is based on body weight and must be determined by your doctor. The usual dose is 0.05 to 0.075 mg once a day.
- Children 1 to 5 years of age—The dose is based on body weight and must be determined by your doctor. The usual dose is 0.075 to 0.1 mg once a day.
- Children 6 to 10 years of age—The dose is based on body weight and must be determined by your doctor. The usual dose is 0.1 to 0.15 mg once a day.
- Children over 10 years of age—The dose is based on body weight and must be determined by your doctor. The usual dose is 0.15 to 0.2 mg once a day.
Levothyroxine side effects
Stop using levothyroxine and get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat. Call your doctor at once if you have any of these serious side effects:
- headache;
- sleep problems (insomnia);
- nervous or irritable feeling;
- fever, hot flashes, sweating;
- changes in your menstrual periods;
- appetite changes, weight changes;
Less serious side effects may include mild hair loss.
This is not a complete list of side effects and others may occur. Tell your doctor about any unusual or bothersome side effect.
