Description and Brand Names

Drug information provided by: Merative, Micromedex®

US Brand Name

  1. Cytomel


Liothyronine is used to treat hypothyroidism, a condition wherein the thyroid gland does not produce enough thyroid hormone. It is also used to help decrease the size of enlarged thyroid glands (goiter) and treat thyroid cancer.

Liothyronine is also used in some medical tests to help diagnose problems with the thyroid gland.

This medicine is available only with your doctor's prescription.

This product is available in the following dosage forms:

  • Tablet

Before Using

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:


Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.


Appropriate studies performed to date have not demonstrated pediatric-specific problems that would limit the usefulness of liothyronine in children. Recommended doses should not be exceeded, and the patient should be carefully monitored during treatment.


Appropriate studies performed to date have not demonstrated geriatrics-specific problems that would limit the usefulness of liothyronine in the elderly. However, elderly patients are more likely to have age-related kidney or heart or blood vessel problems, which may require caution and an adjustment in the dose for patients receiving liothyronine.


There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Drug Interactions

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Furosemide
  • Iopromide
  • Midodrine

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Ethinyl Estradiol
  • Kelp
  • Sevelamer
  • Sodium Polystyrene Sulfonate

Other Interactions

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other Medical Problems

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

  • Adrenal insufficiency (underactive adrenal gland), uncorrected—Should not be used in patients with this condition.
  • Adrenal gland problems or
  • Angina (chest pain), history of or
  • Blood clotting problems or
  • Diabetes or
  • Heart or blood vessel disease (eg, coronary artery disease, heart failure), history of or
  • Heart rhythm problems (eg, arrhythmia, atrial fibrillation), history of—Use with caution. May make these conditions worse.
  • Hypoproteinemia (low levels of protein in the blood), severe or
  • Kidney disease (eg, nephrosis) or
  • Liver disease (eg, hepatitis), severe or
  • Pituitary gland problems (eg, acromegaly) or
  • Porphyria (enzyme problem)—Use with caution. May need to adjust the dose of liothyronine in patients with these conditions.

Proper Use

This medicine will need to be taken for the rest of your life of your child's life. Do not stop taking this medicine or change your doses without first checking with your doctor. It may take several weeks before you start to notice an improvement in your symptoms.

If you use medicine to treat high cholesterol (including cholestyramine, colesevelam, colestipol), Kayexalate®, or sevelamer, take liothyronine at least 4 hours before you take any of these medicines.


The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For oral dosage form (tablet):
    • For hypothyroidism:
      • Adults—At first, 25 micrograms (mcg) once a day. Your doctor may adjust your dose as needed. However, the dose is usually not more than 75 mcg once a day.
      • Older adults—At first, 5 mcg once a day. Your doctor may adjust your dose as needed.
      • Children—At first, 5 mcg once a day. Your doctor may adjust your dose as needed.
    • For thyroid cancer:
      • Adults and children—Use and dose must be determined by your doctor.
    • For thyroid problem diagnosis:
      • Adults— 75 to 100 micrograms (mcg) once a day for 7 days. Your doctor will give you a radioactive iodine before and after the 7-day liothyronine.
      • Children—Use and dose must be determined by your doctor.

Missed Dose

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.


Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.


It is very important that your doctor check your or your child's progress at regular visits. This will allow your doctor to see if the medicine is working properly and to decide if you should continue to take it. Blood tests will be needed to check for unwanted effects.

Liothyronine should not be used for the treatment of obesity or for the purpose of losing weight. This medicine is ineffective for weight reduction and when taken in larger amounts, may cause more serious unwanted effects.

Call your doctor right away if you start to have chest pain, fast or irregular heartbeat, excessive sweating, difficulty with breathing, heat intolerance, nervousness, leg cramps, headache, irritability, sleeplessness, tremors, change in appetite, weight gain or loss, vomiting, diarrhea, fever, changes in menstrual periods, hives, or skin rash. These could be symptoms of too much medicine in your body.

This medicine may cause severe hypothyroidism, called myxedema coma, which may be life-threatening and requires immediate medical attention. Check with your doctor right away if you have the following symptoms: weakness, confusion or non-responsiveness, feeling cold, low body temperature, swelling of the body, especially the face, tongue, and lower legs, or difficulty breathing.

For patients with diabetes: It is very important that you keep track of your blood or urine sugar levels as instructed by your doctor. Check with your doctor right away if you notice any changes in your sugar levels.

If you think you have become pregnant while using this medicine, tell your doctor right away. You may need a larger dose of liothyronine while you are pregnant.

Women who are post-menopausal or who use this medicine for a long time may have some bone loss, which could lead to osteoporosis. Talk with your doctor if you have questions or concerns about this.

A temporary loss of hair may occur during the first few months of liothyronine treatment. Ask your doctor about this if you have any concerns.

Make sure any doctor or dentist who treats you knows that you or your child are using this medicine.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Side Effects

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

Incidence not known

  1. Anxiety
  2. arm, back, or jaw pain
  3. blurred or double vision
  4. chest pain or discomfort
  5. chest tightness or heaviness
  6. crying
  7. decreased bone mineral density
  8. decreased urine output
  9. delusions of persecution, mistrust, suspiciousness, or combativeness
  10. diarrhea
  11. difficulty breathing
  12. dilated neck vein
  13. dizziness
  14. excessive
  15. sweating
  16. extreme tiredness or weakness
  17. eye pain
  18. fainting
  19. false or unusual sense of well-being
  20. fast, pounding, or irregular heartbeat or pulse
  21. feeling of discomfort
  22. feeling of unreality
  23. fever
  24. headache
  25. heat intolerance
  26. impaired fertility
  27. increased appetite
  28. increased blood pressure
  29. irregular breathing
  30. irritability
  31. itching, skin rash
  32. joint swelling
  33. limp pain in the hip or knee
  34. menstrual changes
  35. mental depression
  36. muscle aches, weakness, or cramps
  37. nausea
  38. nervousness
  39. pain or discomfort in the arms, jaw, back, or neck
  40. quick to react or overreact emotionally
  41. rapidly changing moods
  42. restlessness
  43. sense of detachment from self or body
  44. severe headache
  45. slow heartbeat
  46. stomach cramps
  47. swelling of the face, fingers, feet, or lower legs
  48. swollen lymph glands
  49. tremors
  50. trouble sitting still
  51. trouble sleeping
  52. vomiting
  53. weight gain or loss

Get emergency help immediately if any of the following symptoms of overdose occur:

Symptoms of overdose

  1. Cold, clammy skin
  2. confusion about identity, place, and time
  3. difficulty in speaking
  4. dizziness
  5. double vision
  6. fast, weak pulse
  7. headache
  8. inability to move the arms, legs, or facial muscles
  9. inability to speak
  10. lightheadedness
  11. loss of consciousness
  12. nervousness
  13. seizure
  14. sensitivity to heat
  15. slow speech
  16. sweating
  17. trouble sleeping
  18. weight loss

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Incidence not known

  1. Feeling of warmth
  2. hair loss
  3. redness of the face, neck, arms, and occasionally, upper chest

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

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