ATC Code H03AA02
Formula C15H12I3NO4
Molar Mass (g·mol−1) 650,97
Melting Point (°C) 234–238
PKS Value 8.4
CAS Number 6893-02-3
PUB Number 5920
Drugbank ID DB00279
Solubility practically insoluble in water


Liothyronine, also known as T3 or triiodothyronine, is a thyroid hormone. It affects almost every physiological process in the body, including growth and development, metabolism, body temperature, and heart rate. It is most commonly used to treat hypothyroidism and myxedema coma. It can be taken by mouth or by injection into a vein.



Liothyronine is the most potent form of thyroid hormone. Its medical use is as the sodium salt of triiodothyronine (T3), which is chemically similar and pharmacologically equivalent to T3. As such, it acts on the body to increase basal metabolic rate, affect protein synthesis, and increase the body's sensitivity to catecholamines (such as epinephrine) by binding to thyroid receptors within cells. As monotherapy or in combination therapy with SSRIs, liothyronine may also promote new neuron formation in the central nervous system. Thyroid hormones are essential for the proper development and differentiation of all cells in the human body. These hormones also regulate protein, fat, and carbohydrate metabolism and affect how human cells use their energy reserves.


Thyroid hormones are well absorbed orally. Liothyronine is almost completely absorbed and absorption is not affected by food intake. Liothyronine exhibits very high binding to plasma proteins. This is approximately 99.7% of the administered dose. Liothyronine is metabolized mainly in the liver, where it is deiodinated to diiodothyronine and monoiodothyronine, followed by conjugation with glucuronides and sulfates. The main excretion of thyroid hormones is through the kidneys. The half-life of liothyronine is about 1 to 2 days.


Side effects

Liothyronine can cause a number of side effects, most of which are similar to the symptoms of hyperthyroidism:

  • Weight loss
  • Tremor
  • Headache
  • Stomach upset
  • Vomiting
  • diarrhea
  • Stomach cramps
  • nervousness
  • irritability
  • insomnia
  • excessive sweating
  • increased appetite
  • fever
  • changes in the menstrual cycle
  • sensitivity to heat


  • Drugbank
  • PubChem
  • Aktories, Förstermann, Hofmann, Starke: Allgemeine und spezielle Pharmakologie und Toxikologie, Elsvier, 2017

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All information used for the content comes from verified sources (recognised institutions, experts, studies by renowned universities). We attach great importance to the qualification of the authors and the scientific background of the information. Thus, we ensure that our research is based on scientific findings.

Markus Falkenstätter

Markus Falkenstätter

Markus Falkenstätter is a writer on pharmaceutical topics in Medikamio's medical editorial team. He is in the last semester of his pharmacy studies at the University of Vienna and loves scientific work in the field of natural sciences.

Mag. pharm Stefanie Lehenauer

Mag. pharm Stefanie Lehenauer

Stefanie Lehenauer has been a freelance writer for Medikamio since 2020 and studied pharmacy at the University of Vienna. She works as a pharmacist in Vienna and her passion is herbal medicines and their effects.

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