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Combination of
ThyroxineThyroid hormone
TriiodothyronineThyroid hormone
Trade namesThyrolar
Clinical data
  • US: A (No risk in human studies)
Routes of
By mouth
External links
Legal status

Liotrix, sold under the brand name Thyrolar among others, is a medication used to treat low thyroid; though is less preferred than levothyroxine.[1] Other uses may include goiter with normal thyroid function and thyroid cancer.[1] It is taken by mouth.[1]

It is a 4:1 mixture of levothyroxine (T4) and triiodothyronine (T3).

Medical uses

The most common usage is hypothyroidism treatment, via supplementation.[2][3] Other uses include:

Side effects

Adverse effects are mainly due to chronic accidental overdose. Symptoms mimic those of hyperthyroidism and include headache, chest pain, irregular heartbeat, dyspnea, trembling, sweating, diarrhea, and weight loss. These effects can be reduced through titration of the dose levels, but this should be done by the prescribing physician.[4] Sympathomimetic cardiovascular effects including: heart palpitations, chest pain, arrhythmia, sweating, chest pain, and anxiety, require urgent medical attention.[5] Particularly if these signs occur in patients who are at an increased risk for cardiovascular complications i.e. familial or patient history of myocardial infarction, cardiovascular disease, stroke, arteriosclerosis.[2] Hair loss occasionally occurs in the first few months of treatment, but is reversible. The condition is usually self-limiting without altering treatment.[5]


Thyroid agents should not be used to treat obesity, particularly in euthyroid patients. Regular doses in hypothyroid patients are acceptable, but only in the context of treating hypothyroidism. Excessive doses (and regular doses in euthyroid patients) can result in life-threatening cardiovascular events. Patients should be advised against taking sympathomimetic agents, including stimulants and diet pills, while undergoing hypothyroid treatment, as these agents increase the risk of cardiovascular events.[6]

Society and culture

In 2013, Forest Laboratories has released the following statement regarding the limited availability of liotrix: "U.S. Pharmacopeia, an official public standards-setting authority for prescription and over-the-counter medicines and other health care products manufactured or sold in the United States, has mandated new specifications for a component used in the manufacturing of Thyrolar. As a result, all strengths of Thyrolar are currently on long-term back order while modifications necessary to meet these new specifications are made."[7]


  1. 1.0 1.1 1.2 "Liotrix Monograph for Professionals". Archived from the original on 18 May 2021. Retrieved 23 November 2021.
  2. 2.0 2.1 "Liotrix (Professional Patient Advice)". Archived from the original on 2020-10-20. Retrieved 2021-10-09.
  3. Skidmore-Roth L (2015). "Liotrix". Mosby's 2015 nursing drug reference (Twenty-eight ed.). Saint Louis, Missouri: Elsevier Health Sciences. p. 713. ISBN 978-0-323-28693-0. Archived from the original on 2021-10-09. Retrieved 2021-10-09.
  4. "LIOTRIX - ORAL (Thyrolar) side effects, medical uses, and drug interactions". MedicineNet. Archived from the original on 2021-04-21. Retrieved 2021-10-09.
  5. 5.0 5.1 "Thyrolar (Liotrix) dosing, indications, interactions, adverse effects, and more". MedScape. Archived from the original on 2021-02-26. Retrieved 2021-10-09.
  6. "Thyrolar (Liotrix) dosing, indications, interactions, adverse effects, and more". MedScape. Archived from the original on 2021-02-26. Retrieved 2021-10-09.
  7. "Thyrolar". Forest Pharmaceuticals, Inc. Archived from the original on 11 August 2008.

External links