liothyronine
Liothyronine (Cytomel) is a thyroid hormone medication that can be used for a number of thyroid-related health concerns. More specifically, it's a lab-made form of the T3 thyroid hormone that's made by your thyroid gland. People of all ages can take this medication, and it's generally taken by mouth just once daily. Although weight loss is a potential side effect of liothyronine (Cytomel), it should not be taken solely for this purpose.
What is Liothyronine (Cytomel)?
What is Liothyronine (Cytomel) used for?
Hypothyroidism (low thyroid hormone levels)
Thyroid cancer (with radiation and surgery)
Thyroid suppression test to help with diagnosis
How Liothyronine (Cytomel) works
Liothyronine (Cytomel) is a lab-made version of the T3 thyroid hormone that's normally made by your thyroid gland. Your thyroid hormones have important functions, such as controlling your metabolism, vital signs like body temperature and heart rate, and more.
When the amount of thyroid hormone in your body is too low, taking thyroid replacement hormones like liothyronine (Cytomel) can bring your levels back to normal.
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What are the side effects of Liothyronine (Cytomel)?
Common Side Effects
- Shakiness
- Fast or irregular heartbeat
- Fever
- Sweating
- Easily feel hot
- Hair loss
- Larger appetite
- Diarrhea
- Weight loss
- Weak muscles
- Fatigue
- Nervousness or anxiety
- Irritability
- Trouble sleeping
- Trouble breathing
Serious Side Effects
- Heart problems (e.g., heart attack): chest pain; shortness of breath; feeling weak; breaking into a cold sweat; pain that spreads to the jaw, neck, back, shoulders, arms
Source: DailyMed
The following side effects have also been reported
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
arm, back, or jaw pain
blurred or double vision
chest pain or discomfort
chest tightness or heaviness
crying
decreased bone mineral density
decreased urine output
delusions of persecution, mistrust, suspiciousness, or combativeness
difficulty breathing
dilated neck vein
dizziness
excessive
sweating
extreme tiredness or weakness
fainting
false or unusual sense of well-being
fast, pounding, or irregular heartbeat or pulse
feeling of discomfort
feeling of unreality
headache
heat intolerance
impaired fertility
increased appetite
increased blood pressure
irregular breathing
irritability
itching, skin rash
joint swelling
limp pain in the hip or knee
menstrual changes
mental depression
muscle aches, weakness, or cramps
nervousness
pain or discomfort in the arms, jaw, back, or neck
quick to react or overreact emotionally
rapidly changing moods
restlessness
sense of detachment from self or body
severe headache
slow heartbeat
stomach cramps
swelling of the face, fingers, feet, or lower legs
swollen lymph glands
trouble sitting still
trouble sleeping
vomiting
weight gain or loss
Get emergency help immediately if any of the following symptoms of overdose occur:
Symptoms of overdose
Cold, clammy skin
confusion about identity, place, and time
difficulty in speaking
dizziness
double vision
fast, weak pulse
headache
inability to move the arms, legs, or facial muscles
inability to speak
lightheadedness
loss of consciousness
nervousness
seizure
sensitivity to heat
slow speech
sweating
trouble sleeping
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
Feeling of warmth
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.
Pros and cons of Liothyronine (Cytomel)
Pros
Acts faster than other thyroid hormone replacement therapies
Safe to use during pregnancy
Safe to use in children
Available as a lower-cost generic version
Cons
Requires regular blood tests and frequent dose adjustments at first to make sure you're getting the right dose
Has a risk for heart problems
Can't use if you have untreated adrenal insufficiency
Shouldn't be used to treat conditions that aren't related to abnormal thyroid function (e.g., benign thyroid nodules, nontoxic goiter, swelling of the thyroid gland caused by infection)
Pharmacist tips for Liothyronine (Cytomel)
Try to take liothyronine (Cytomel) at the same time each day to help your thyroid hormone levels stay the same from day to day. Choose a time during the day that's easy for you to remember so you can make it part of your daily routine. This can be helpful to avoid missing doses of your medication.
Make sure to get regular blood tests done when your prescriber asks. These blood tests check your thyroid hormone levels. They're important for helping your prescriber make sure you're taking a dose of liothyronine (Cytomel) that works well and is safe for you.
Most of the side effects that you might have while you're taking liothyronine (Cytomel) are symptoms of hyperthyroidism and it usually means that your dose is too high. Let your prescriber know if you have side effects like shakiness, a racing heart, or nervousness. Your prescriber might need to lower your dose.
Tell your prescriber and pharmacist about all the medications and supplements that you're taking. Liothyronine (Cytomel) can interfere with how other medications work. Examples include blood thinners, insulin, and cholestyramine (Prevalite). Your care team can recommend dose adjustments or changes to your treatment plan. This makes sure that your medications work well and are safe for you to take together.
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What are the risks and warnings for Liothyronine (Cytomel)?
Liothyronine (Cytomel) can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.
Not for weight loss
Risk factors: Taking other medications for weight loss
Liothyronine (Cytomel) shouldn't be used for weight loss. It’s not recommended, safe, or effective for this purpose. Taking high doses of liothyronine (Cytomel) can cause serious or deadly effects, especially if it's taken with other medications for weight loss like phentermine (Adipex-P). Speak with a healthcare professional (HCP) if your goal is to lose weight to figure out what the best approach to weight management is for you.
Heart problems
Risk factors: Currently have heart disease | Age 65 or older | Taking stimulant medications
Taking too much liothyronine (Cytomel) can cause heart problems, especially for older adults and for people with heart conditions. Because of this risk, the dose of liothyronine (Cytomel) that you start with might be lower than usual if you're older than 65 or if you have a heart condition.
Call your prescriber or get medical care right away if you have a rapid or irregular heartbeat, chest pain, or shortness of breath. Your prescriber might lower your dose of liothyronine (Cytomel) or ask you to stop taking the medication for a week before restarting it at a lower dose.
Adrenal crisis in people with adrenal insufficiency
Risk factors: Adrenal insufficiency | Addison's disease
For people who also have adrenal insufficiency (a condition of low adrenal hormone levels), it's important to start treatment for the adrenal hormone problem first with corticosteroids before starting liothyronine (Cytomel). This is because thyroid hormones can make the body process corticosteroids faster. Starting thyroid hormone replacement before treating adrenal insufficiency can cause your adrenal hormones to drop to very low levels and make you feel unwell.
Let your prescriber know about your full medical history before you start taking liothyronine (Cytomel). They might check your adrenal hormone levels to see whether this situation applies to you before you start thyroid hormone replacement therapy. Get medical attention right away if you experience signs of adrenal crisis, like stomach pain, dehydration, dizziness, high fever, nausea, or vomiting, while you're taking this medication.
Worsening diabetes
Risk factors: Taking diabetes medications
For people with diabetes, taking liothyronine (Cytomel) affect how well the body can regulate blood sugar levels. This can change the required dose of any diabetes medications that you're taking. Check your blood sugar levels when you first start taking liothyronine (Cytomel), when the dose of your thyroid medication changes, when you stop the thyroid medication, and as directed by your prescriber. Talk to your care team if your blood sugar levels are unusual.
Effect on bones if dose is too high
Risk factors: People who've reached menopause | Long-term treatment | Too high dose of liothyronine (Cytomel)
Taking liothyronine (Cytomel) at a dose that's too high for you can weaken your bones over time. This risk is higher for people who've gone through menopause. Your prescriber will check your thyroid hormone levels to make sure that you're taking the lowest dose of the medication that works well to treat your condition. This helps lower your risk for bone problems related to overtreatment.
Liothyronine (Cytomel) dosage forms
Typical dosing for Liothyronine (Cytomel)
The dose of liothyronine (Cytomel) will vary from person to person. It depends on many things, such as why you're taking the medication and your thyroid function test results.
Hypothyroidism: The typical dose ranges from 25 mcg to 75 mcg by mouth once daily.
Thyroid cancer: The dose will depend on the target TSH (thyroid stimulating hormone) level that's set by your prescriber.
Thyroid suppression test: The typical dose ranges from 75 mcg to 100 mcg by mouth once daily for 7 days.
Interactions between Liothyronine (Cytomel) and other drugs
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.
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.
- Kelp
- Sevelamer
- Sodium Polystyrene Sulfonate
How much does Liothyronine (Cytomel) cost?
Liothyronine (Cytomel) contraindications
Untreated adrenal insufficiency
What are alternatives to Liothyronine (Cytomel)?
Hypothyroidism (low thyroid hormone levels)
Thyroid cancer (with radiation and surgery)
Thyroid suppression test to help with diagnosis
Hypothyroidism (low thyroid hormone levels)
Thyroid cancer (together with radiation and surgery)
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References
Best studies we foundAmerican Thyroid Association. (n.d.). Thyroid nodules.
AvKARE. (2024). Liothyronine sodium tablet [package insert]. DailyMed.
Boucai, L., et al. (2024). Simple nontoxic goiter. Merck Manual Consumer Version.
Dayan, C., et al. (2018). Management of hypothyroidism with combination thyroxine (T4) and triiodothyronine (T3) hormone replacement in clinical practice: A review of suggested guidance. Thyroid Research.
Garber, J. R., et al. (2012). Clinical Practice Guidelines for hypothyroidism in adults: Cosponsored by the American Association of Clinical Endocrinologists and the American Thyroid Association. Endocrine Practice.
MedlinePlus. (2023). Acute adrenal crisis.
MedlinePlus. (2024). Thyroid function tests.
MedlinePlus. (2024). TSH test.
National Institute of Diabetes and Digestive and Kidney Diseases. (2018). Definition & facts of adrenal insufficiency & Addison’s disease.
National Institute of Diabetes and Digestive and Kidney Diseases. (2018). Symptoms & causes of adrenal insufficiency & Addison’s disease.
Your and Your Hormones. (2022). Thyroid gland.
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