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Liothyronine (By mouth)

Liothyronine Sodium (lye-oh-THYE-roe-neen SOE-dee-um)

Treats hypothyroidism, an enlarged thyroid gland (goiter), and thyroid cancer. Also helps diagnose problems of the thyroid gland.

Brand Name(s):

Cytomel

There may be other brand names for this medicine.

When This Medicine Should Not Be Used:

This medicine is not right for everyone. Do not use it if you had an allergic reaction to liothyronine, or if you have uncorrected adrenal gland problems. Do not use this medicine to treat obesity or to lose weight.

How to Use This Medicine:

Tablet

  • Take your medicine as directed. Your dose may need to be changed several times to find what works best for you.
  • Missed dose: Take a dose as soon as you remember. If it is almost time for your next dose, wait until then and take a regular dose. Do not take extra medicine to make up for a missed dose.
  • Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.

Drugs and Foods to Avoid:

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

  • Many medicines can affect how liothyronine works. Make sure your doctor knows about all other medicines you are using, especially the following:
    • Amiodarone, asparaginase, carbamazepine, clofibrate, digitalis, fluorouracil, furosemide, heroin, imatinib, ketamine, methadone, mitotane, nicotinic acid, phenobarbital, phenytoin, rifampin, salicylate, tamoxifen
    • Beta blockers (including propranolol)
    • Birth control pills (including estrogen)
    • Blood thinner (including heparin, warfarin)
    • Insulin or oral diabetes medicine
    • Medicine to treat depression
    • NSAID pain medicine (including mefenamic acid)
    • Steroid medicine (including dexamethasone)
  • If you use medicine to treat high cholesterol (including cholestyramine, colesevelam, colestipol), or sevelamer, or sodium polystyrene, take liothyronine at least 4 hours before you take any of these medicines.

Warnings While Using This Medicine:

  • Tell your doctor if you are pregnant or breastfeeding, or if you have kidney disease, liver disease, heart or blood vessel disease, diabetes, blood clotting problems, adrenal gland problems, or pituitary gland problems.
  • This medicine may cause the following problems:
    • Heart and heart rhythm problems
    • Myxedema coma, which may be life-threatening
    • Adrenal gland problems
    • Low bone mineral density
  • Do not stop using this medicine without asking your doctor, even if you feel well. This medicine will replace a hormone that is normally produced by your thyroid gland. You may have to take this medicine for the rest of your life.
  • Tell any doctor or dentist who treats you that you are using this medicine.
  • Your doctor will do lab tests at regular visits to check on the effects of this medicine. Keep all appointments.
  • Keep all medicine out of the reach of children. Never share your medicine with anyone.

Possible Side Effects While Using This Medicine:

Call your doctor right away if you notice any of these side effects:

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
  • Bone pain
  • Changes in skin color, dark freckles
  • Chest pain, trouble breathing, fast or uneven heartbeat
  • Cold feeling, weakness, tiredness, nausea, vomiting, weight loss, confusion
  • Leg cramps, headache, nervousness, irritability, tremors, excessive sweating, heat intolerance, fever, changes in menstrual periods
  • Rapid weight gain, swelling in your face, hands, ankles, or feet

If you notice these less serious side effects, talk with your doctor:

  • Diarrhea
  • Temporary hair loss

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088


Last Updated: 3/19/2020

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