What is liothyronine?

Liothyronine is a naturally occurring hormone produced by the thyroid. It is important for normal energy and metabolism. For a variety of reasons, the body may not produce enough of this hormone on its own. In these cases, liothyronine is taken to replace the body’s natural thyroid hormone.

Liothyronine is used to treat hypothyroidism (low thyroid function). Liothyronine is also used to prevent and treat goiter (growth or enlargement of the thyroid gland). Causes of goiter include hormonal imbalances, radiation, surgery, and cancer.

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


Since thyroid hormone occurs naturally in your body, almost anyone can take this drug. In general, liothyronine should not be taken if you have other hormonal problems that are not being adequately treated.

Before taking this medication, tell your doctor if you have heart diseases such as coronary artery disease, hypertension, and angina. These conditions may be affected by thyroid therapy, and closer monitoring may be necessary at the start of therapy.

Changes in blood sugar may also occur in diabetics, and special monitoring may be necessary.

Liothyronine is in the FDA pregnancy category A. This means that liothyronine is safe for use during pregnancy. It is also safe to take liothyronine if you are breast-feeding a baby. This drug does pass into breast milk but it not considered harmful to a nursing infant.

Do not change brands or change to a generic liothyronine drug product without first talking to your doctor. Some liothyronine products may not be interchangeable.

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Seek emergency medical treatment if an overdose is suspected.

Symptoms of a liothyronine overdose include chest pain, nervousness, trouble sleeping, tremor, rapid heartbeat, nausea, headache, fever, sweating, shortness of breath, heat intolerance, irregular menses, increased appetite, decreased weight, diarrhea, and abdominal pain.

Take the missed dose as soon as you remember. However, if it is almost time for the next dose, skip the missed dose and take only the next regularly scheduled dose. Do not take a double dose of this medication.

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Side effects

If you experience any of the following serious side effects, stop taking liothyronine and seek emergency medical attention or contact your doctor immediately:

  • an allergic reaction (difficulty breathing; closing of the throat; swelling of the lips, tongue, or face; or hives);
  • vomiting; or
  • chest pain, irregular heartbeat, or shortness of breath.

Other, less serious side effects may be more likely to occur. Continue to take liothyronine and talk to your doctor or try another similar medication if you experience:

  • tremor, nervousness, or irritability;
  • headache;
  • insomnia;
  • diarrhea, changes in appetite, or weight loss;
  • leg cramps;
  • menstrual irregularities; or
  • fever, sweating, or heat sensitivity.

Side effects other than those listed here may also occur. Talk to your doctor about any side effect that seems unusual or that is especially bothersome. You may report side effects to FDA at 1-800-FDA-1088.

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Other drugs may bind to liothyronine and reduce the amount that is available in the body, making it less effective. Separate liothyronine doses from the following medicines:

  • antacids that contain aluminum,
  • the prescription ulcer medicine sucralfate (Carafate),
  • the cholesterol-lowering drugs cholestyramine (Questran) and colestipol (Colestid), and
  • ferrous sulfate (a type of iron supplement).

Drugs other than those listed here may also interact with liothyronine or affect your condition. Talk to your doctor and pharmacist before taking any prescription or over-the-counter medicines, including vitamins, minerals, and herbal products.

Other Names

Cytomel, Triostat, and liothyronine

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Every effort has been made to ensure that the information provided by Cerner Multum, Inc. ('Multum') is accurate, up-to-date, and complete, but no guarantee is made to that effect. Drug information contained herein may be time sensitive. Multum information has been compiled for use by healthcare practitioners and consumers in the United States and therefore Multum does not warrant that uses outside of the United States are appropriate, unless specifically indicated otherwise. Multum's drug information does not endorse drugs, diagnose patients or recommend therapy. Multum's drug information is an informational resource designed to assist licensed healthcare practitioners in caring for their patients and/or to serve consumers viewing this service as a supplement to, and not a substitute for, the expertise, skill, knowledge and judgment of healthcare practitioners. The absence of a warning for a given drug or drug combination in no way should be construed to indicate that the drug or drug combination is safe, effective or appropriate for any given patient. Multum does not assume any responsibility for any aspect of healthcare administered with the aid of information Multum provides. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the drugs you are taking, check with your doctor, nurse or pharmacist.

Copyright 1996-2004 Cerner Multum, Inc. Version 2.05. Revision date 8/23/04

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