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Cytomel Side Effects

Generic name: liothyronine

Medically reviewed by Last updated on Jan 11, 2024.

Note: This document contains side effect information about liothyronine. Some dosage forms listed on this page may not apply to the brand name Cytomel.

Applies to liothyronine: oral tablet. Other dosage forms:


Oral route (Tablet)

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.

Serious side effects of Cytomel

Along with its needed effects, liothyronine (the active ingredient contained in Cytomel) 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 while taking liothyronine:

Incidence not known

Get emergency help immediately if any of the following symptoms of overdose occur while taking liothyronine:

Symptoms of overdose

Other side effects of Cytomel

Some side effects of liothyronine 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

For Healthcare Professionals

Applies to liothyronine: compounding powder, intravenous solution, oral tablet.


Reported side effects are usually indicative of excessive dosage and will usually disappear when the dose is reduced or treatment is stopped.[Ref]


Common (1% to 10%): Arrhythmia, tachycardia, cardiopulmonary arrest, hypotension, myocardial infarction

Frequency not reported: Angina, congestive heart failure, hypertension, flushing, palpitation[Ref]

Nervous system

Frequency not reported: Headache, tremor, benign intracranial hypertension[Ref]


Frequency not reported: Allergic skin reaction, sweating, rash pruritus, transient hair loss[Ref]


Frequency not reported: Twitching, muscle cramps, muscle weakness, craniostenosis, premature closure of epiphysis[Ref]


Frequency not reported: Diarrhea, vomiting[Ref]


Frequency not reported: Hypersensitivity reaction[Ref]


Frequency not reported: Phlebitis[Ref]


Frequency not reported: Restlessness, excitability, insomnia[Ref]


Frequency not reported: Menstruation irregular[Ref]


Frequency not reported: Fever, edema, weight loss, heat intolerance[Ref]

Frequently asked questions


1. Product Information. Cytomel (liothyronine). Monarch Pharmaceuticals Inc. 2001;PROD.

2. Product Information. Triostat (liothyronine). JHP Pharmaceuticals. 2005.

3. Cerner Multum, Inc. UK Summary of Product Characteristics.

4. Cerner Multum, Inc. Australian Product Information.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.