Cytomel® (liothyronine sodium)

Liothyronine general information

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.

Liothyronine dosage and administration

Take this medication exactly as directed by your doctor. If you do not understand these directions, ask your doctor, nurse, or pharmacist to explain them to you.

Take each dose with a full glass (8 ounces) of water.

Take this medication at the same time each day. Thyroid hormone is usually taken in the morning to prevent insomnia at night

It is important to take liothyronine regularly to get the most benefit.

• Adults and teenagers—At first, 25 micrograms (mcg) a day. Some patients with very serious conditions caused by too little thyroid hormone may need to take only 2.5 to 5 mcg a day at first. Also, some patients with heart disease or the elderly may need lower doses at first. Then, your doctor may increase your dose a little at a time to up to 50 mcg a day if needed. Your doctor may want you to divide your dose into smaller amounts that are taken two or more times a day.

• Adults—At first, 5 mcg a day. Some patients with heart disease or the elderly may need lower doses at first. Then, your doctor may increase your dose a little at a time to 50 to 100 mcg a day.

Liothyronine 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.