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.
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.
Levothyroxine is in the FDA pregnancy category A. This means that it is safe to use while you are pregnant. It is also safe to use while you are breast-feeding a baby. This drug does pass into breast milk, but it is not expected to be harmful to a nursing infant.
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.
Do not change brands or change to a generic levothyroxine drug product without first asking your doctor. Different brands of levothyroxine may not work the same. If you get a prescription refill and your new pills look different, talk with your pharmacist or doctor.
Avoid the following food products, which can make your body absorb less levothyroxine: infant soy formula, cotton seed meal, walnuts, and high-fiber foods.
Seek emergency medical attention if you think you have used too much of this medicine.
Overdose symptoms may include chest pain, pounding heartbeat, tremor, shortness of breath, leg cramps, confusion, vomiting, diarrhea, or seizures.
Take the missed dose as soon as you remember. If it is almost time for your next dose, skip the missed dose and take the medicine at the next regularly scheduled time. Do not take extra medicine to make up the missed dose.
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:
- 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. You may report side effects to FDA at 1-800-FDA-1088.
The following drugs may cause medical problems if you use them with levothyroxine: lithium, amiodarone, or antidepressants. Tell your doctor if you have recently received radiation therapy with iodine (such as I-131).
This list is not complete and there are many other drugs that can interact with 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.
Certain medicines can be continued, but they may make levothyroxine less effective if taken at the same time. If you use any of the following drugs, use them at least 4 hours before or 4 hours after you take levothyroxine:
- calcium carbonate (Caltrate, Citracal, Oystercal, and others);
- ferrous sulfate iron supplement;
- sucralfate (Carafate);
- sodium polystyrene sulfonate (Kayexalate, Kionex, and others);
- antacids that contain aluminum (Amphojel, Gaviscon, Maalox, Mylanta, Riopan, Rulox, Tums, and others); and
- cholesterol-lowering drugs cholestyramine (Questran) and colestipol (Colestid).
Eltroxin, Levo-T, Levotabs, Levothroid, Levoxyl, Synthroid, Unithroid, l-thyroxine, levothyroxine, Euthyrox, Eutroxsig, Evotrox, Levotec, LEVOTHYROX, L THYROXINE ROCHE, Oroxine, and Tirosint
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