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    HomeMedication GuideLiothyronine safety
    Thyroid hormone (T3)FDA-Approved

    Liothyronine: What to Know Before You Take It

    Also known as Cytomel

    Other names: liothyronine-t3, liothyronine-t3, t3, cytomel, liothyronine-sodium

    Liothyronine is a synthetic form of triiodothyronine (T3), the biologically active thyroid hormone. It is FDA-approved for hypothyroidism and as a pituitary TSH suppression agent in thyroid cancer management.

    FDA-approved as Cytomel for hypothyroidism, myxedema coma (IV form), and as an adjunct in thyroid cancer management. Compounded liothyronine capsules are also dispensed by licensed pharmacies.
    Reviewed by the OmniRx Health clinical team•Last reviewed Jul 4, 2026

    FDA boxed warning

    WARNING: NOT FOR TREATMENT OF OBESITY OR FOR WEIGHT LOSS Thyroid hormones, including liothyronine sodium tablets, either alone or with other therapeutic agents, should not be used for the treatment of obesity or for weight loss. In euthyroid patients, doses within the range of daily hormonal requirements are ineffective for weight reduction. Larger doses may produce serious or even life-threatening manifestations of toxicity, particularly when given in association with sympathomimetic amines such as those used for their anorectic effects [see Adverse Reactions (6) , Drug Interactions (7.7) , and Overdosage (10) ] . WARNING: NOT FOR TREATMENT OF OBESITY OR FOR WEIGHT LOSS See full prescribing information for complete boxed warning. Thyroid hormones, including liothyronine sodium tablets, should not be used for the treatment of obesity or for weight loss. Doses beyond the range of daily hormonal requirements may produce serious or even life-threatening manifestations of toxicity ( 6 , 7.7 , 10 ).

    In plain language

    What Liothyronine is used for

    • Hypothyroidism (especially in patients with conversion issues from T4 to T3)
    • Thyroid cancer (TSH suppression adjunct)

    Taking this medicine

    How it is administered

    • Oral capsule
    • Oral tablet

    Read before you decide

    Risks and precautions

    Risks and warnings

    • Elevated heart rate and blood pressure
    • Palpitations
    • Jitteriness, insomnia
    • Bone density loss with long-term excess dosing

    Who should not take it

    • Uncorrected adrenal insufficiency
    • Untreated hyperthyroidism
    • Acute myocardial infarction

    Medication review

    Liothyronine drug interactions

    Liothyronine + Amitriptyline7.5 Antidepressant Therapy Concurrent use of tricyclic (e.g., amitriptyline) or tetracyclic (e.g., maprotiline) antidepressants and liothyronine sodium tablets may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines.Moderate interactionLiothyronine + DexamethasoneGlucocorticoids (e.g., Dexamethasone ≥4 mg/day) Short-term administration of large doses of glucocorticoids may decrease serum T3 concentrations by 30% with minimal change in serum T4 levels.Moderate interactionLiothyronine + AmiodaroneOther drugs: Amiodarone Amiodarone inhibits peripheral conversion of levothyroxine (T4) to triiodothyronine (T3) and may cause isolated biochemical changes (increase in serum free-T4, and decreased or normal free-T3) in clinically euthyroid patients.Minor interactionLiothyronine + CarbamazepineOther drugs: Carbamazepine Furosemide (>80 mg IV) Heparin Hydantoins Non-Steroidal Anti-inflammatory Drugs - Fenamates These drugs may cause protein binding site displacement.Minor interactionLiothyronine + FurosemideOther drugs: Carbamazepine Furosemide (>80 mg IV) Heparin Hydantoins Non-Steroidal Anti-inflammatory Drugs - Fenamates These drugs may cause protein binding site displacement.Minor interactionLiothyronine + LevothyroxineOther drugs: Amiodarone Amiodarone inhibits peripheral conversion of levothyroxine (T4) to triiodothyronine (T3) and may cause isolated biochemical changes (increase in serum free-T4, and decreased or normal free-T3) in clinically euthyroid patients.Minor interactionLiothyronine + PhenytoinPhenytoin and carbamazepine reduce serum protein binding of thyroid hormones, and total and FT4 may be reduced by 20% to 40%, but most patients have normal serum TSH levels and are clinically euthyroid.Minor interactionLiothyronine + PropranololDrug or Drug Class Effect Beta-adrenergic antagonists (e.g., Propranolol >160 mg/day) In patients treated with large doses of propranolol (>160 mg/day), T3 and T4 levels change, TSH levels remain normal, and patients are clinically euthyroid.Minor interactionLiothyronine + RifampinDrug or Drug Class Effect Phenobarbital Rifampin Phenobarbital has been shown to reduce the response to thyroxine.Minor interactionLiothyronine + SertralineAdministration of sertraline in patients stabilized on liothyronine sodium tablets may result in increased liothyronine sodium tablets requirements.Minor interaction
    Check this against your full medication list in the Interaction Checker

    FDA safety data

    Most-reported side effects

    Based on 8,568 FAERS reports. Reports do not prove the drug caused the effect.

    drug ineffective 952headache 875fatigue 837nausea 578dyspnoea 555pain 479hypertension 464malaise 439weight increased 437hypothyroidism 429feeling abnormal 418dizziness 394
    Explore full FDA safety data

    Regulatory record

    FDA recalls (14)

    Class IITerminated · Dec 4, 2023

    Failed Impurities/Degradation Specifications

    Recalling firm: SUN PHARMACEUTICAL INDUSTRIES INC

    Class IITerminated · Oct 20, 2023

    Failed Impurities/Degradation Specifications.

    Recalling firm: SUN PHARMACEUTICAL INDUSTRIES INC

    Class IITerminated · Oct 20, 2023

    Failed Impurities/Degradation Specifications.

    Recalling firm: SUN PHARMACEUTICAL INDUSTRIES INC

    Class ITerminated · Apr 29, 2021

    Subpotent Drug

    Recalling firm: Acella Pharmaceuticals, LLC

    Class ITerminated · Apr 29, 2021

    Subpotent Drug

    Recalling firm: Acella Pharmaceuticals, LLC

    Class ITerminated · Apr 29, 2021

    Subpotent Drug

    Recalling firm: Acella Pharmaceuticals, LLC

    Class ITerminated · Apr 29, 2021

    Subpotent Drug

    Recalling firm: Acella Pharmaceuticals, LLC

    Class ITerminated · Apr 29, 2021

    Subpotent Drug

    Recalling firm: Acella Pharmaceuticals, LLC

    Class ITerminated · Sep 17, 2020

    Subpotent Drug: FDA analysis found these products to be less than the labeled claim for the levothyroxine (T4) portion of the product.

    Recalling firm: Acella Pharmaceuticals, LLC

    Class ITerminated · Sep 17, 2020

    Subpotent Drug: FDA analysis found these products to be less than the labeled claim for the levothyroxine (T4) portion of the product.

    Recalling firm: Acella Pharmaceuticals, LLC

    Class ITerminated · May 22, 2020

    Superpotent Drug.

    Recalling firm: Acella Pharmaceuticals, LLC

    Class ITerminated · May 22, 2020

    Superpotent Drug.

    Recalling firm: Acella Pharmaceuticals, LLC

    Common questions

    Patient questions

    Should I take T3 (liothyronine) or T4 (levothyroxine)?

    Most people with hypothyroidism are managed with levothyroxine (T4), which the body converts to T3. Liothyronine (T3) has a shorter half-life, faster onset, and requires more careful dosing. Some individuals with conversion problems may benefit from T3 or combination therapy. A licensed provider determines the appropriate regimen based on labs and symptoms.

    This information is educational — not medical advice.

    This page is provided for general educational purposes and summarizes publicly available data from sources such as the U.S. Food & Drug Administration. It is not a substitute for the judgment of a licensed clinician and should not be used to start, stop, or change any medication. It may be incomplete or out of date, and individual circumstances vary. Always talk with your prescriber or pharmacist about your specific medications and health conditions. If you think you may have a medical emergency, call 911.

    Have medication questions?

    A licensed OmniRx provider can review your health history and medication list. Availability and treatment options are determined individually.

    Sources & References

    Learn more about where our data comes from and how we write and review medical content.