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Liothyronine sodium

Tiromel · ATC code H03AA02

Also known as: Liothyronin-Natrium, Liyotironin sodyum · Brand names: Thybon, Thyrotardin-Inject., Tiromel, Cytomel, Liomny

Key facts
Active substance
Liothyronine sodium
Drug class
Thyroid hormone
ATC code
H03AA02
Authorisation
authorised nationally; no central EU authorisation
Information as of
2026-10-29

Boxed warning

  • • Thyroid hormones, including LIOTHYRONINE SODIUM, 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)].

Key facts

Liothyronine sodium is a synthetic thyroid hormone (T3). Per the US prescribing information, it is used as replacement in hypothyroidism, for TSH suppression in thyroid cancer and in the thyroid suppression test.

What it is used for

  • Replacement therapy in primary, secondary and tertiary, congenital or acquired hypothyroidism
  • Adjunct to surgery and radioiodine in well-differentiated thyroid cancer (TSH suppression)
  • Diagnostic suppression test for suspected mild hyperthyroidism or thyroid gland autonomy
  • Not for benign nodules or nontoxic goiter in iodine-sufficient patients, nor during recovery from subacute thyroiditis

Dosing

  • Orally once daily; individualize by age, weight, cardiovascular status, concomitant conditions and laboratory values
  • Adults with hypothyroidism: start 25 mcg once daily, increase by 25 mcg every 1 or 2 weeks if needed; usual maintenance 25 mcg to 75 mcg once daily
  • Elderly or cardiac disease: start 5 mcg once daily, increase in 5 mcg increments
  • Children: start 5 mcg once daily, increase by 5 mcg every 3 to 4 days; above 3 years the full adult dosage may be needed
  • In secondary or tertiary hypothyroidism monitor serum T3, not TSH; pregnancy: see the full text

Contraindications

  • Uncorrected adrenal insufficiency

Important warnings

  • Boxed warning: not for obesity or weight loss; larger doses may produce serious or life-threatening toxicity, particularly with sympathomimetic amines
  • In the elderly and with cardiovascular disease, overtreatment may precipitate angina or arrhythmias; start at lower doses
  • Oral products are not recommended to treat myxedema coma
  • Acute adrenal crisis in adrenal insufficiency; replace glucocorticoids first
  • Narrow therapeutic index; avoid over- or undertreatment

Side effects

  • Mainly signs of hyperthyroidism from overdosage: fatigue, weight loss, heat intolerance, sweating, headache, nervousness, insomnia, tremors
  • Palpitations, tachycardia, arrhythmias, heart failure, angina, myocardial infarction
  • Diarrhea, hair loss, decreased bone mineral density, menstrual irregularities; in children pseudotumor cerebri and slipped capital femoral epiphysis

Interactions

  • Bile acid sequestrants and ion exchange resins (e.g. colesevelam, cholestyramine, sevelamer): give liothyronine at least 4 hours before
  • Oral anticoagulants: increased response, anticoagulant dose may need lowering
  • Antidiabetics: glycemic control may worsen; digitalis glycosides: reduced effect
  • Sympathomimetics: risk of coronary insufficiency

Pregnancy and breastfeeding

  • No increased rates of major birth defects or miscarriage reported; do not discontinue in pregnancy, monitor TSH and adjust the dose
  • Present in human milk in limited studies

Summary of the official product information, written with AI on 2026-10-29. Every number was checked automatically against the original text. Not reviewed by a physician – the full official text is authoritative.

Full official text →

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For patients

Patient information (US)

This product has no separate US patient information.

Authorisation and brand names by country

Medicines with exactly this active-substance composition, as listed in the national registers – alphabetical and without ranking. Whether a product is currently available is not shown here.

Germany

  • ThybonSanofi-Aventis Deutschland Gmbh · 2 register entries
  • Thyrotardin-Inject.Sanofi-Aventis Deutschland Gmbh · 1 register entry

Source: EMA – Article 57 product data (EU/EEA), as of 2026-10-29

Turkey

  • TiromelİBRAHİM HAYRİ BARUT VERESESİBELMA, NESRİN VE NEZİH BARUT · 2 register entries

Source: TİTCK – Ruhsatlı Beşeri Tıbbi Ürünler Listesi, as of 2026-10-16

USA

  • CytomelPfizer Laboratories Div Pfizer Inc · 1 register entry
  • LiomnySIGMAPHARM LABORATORIES, LLC · 1 register entry

Source: U.S. FDA – Drug labels (openFDA/DailyMed), as of 2026-10-29

Brand names in 7 more European countries
Denmark
Liopent
France
Cynomel, Thybon
Greece
T3
Italy
Liotir
Netherlands
Cytomel, Liopent
Norway
Liothyronin Orifarm Healthcare
Sweden
Liopent, Liothyronin

EMA – Article 57 product data (EU/EEA), 2026-10-29

Medelix receives no money from pharmaceutical companies. Brand names are listed alphabetically and without ranking.

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Sources

  1. U.S. Food and Drug Administration. Liothyronine Sodium (Mylan Pharmaceuticals Inc.) – Prescribing Information, 2026-06-04. DailyMed (NLM), 2026-10-29. https://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=115a84c2-0126-4dd7-816e-1873875f1e49
  2. EMA – Article 57 product data (EU/EEA), 2026-10-29. https://www.ema.europa.eu/en/human-regulatory-overview/post-authorisation/data-medicines-iso-idmp-standards-post-authorisation/public-data-article-57-database
  3. TİTCK – Ruhsatlı Beşeri Tıbbi Ürünler Listesi, 2026-10-16. https://www.titck.gov.tr/dinamikmodul/85
  4. U.S. FDA – Drug labels (openFDA/DailyMed), 2026-10-29. https://dailymed.nlm.nih.gov/dailymed/
  5. Wikidata (CC0): ATC H03AA.

Editorial: Medelix editorial team · last updated 2026-10-29 · How these pages are made · Report an error

Source: U.S. Food and Drug Administration (FDA), prescribing information, via DailyMed (NLM); public domain. Not advertising, not a treatment recommendation. For questions about your own treatment, ask your doctor or pharmacist.