Cytomel Side Effects

Generic name: liothyronine

Medically reviewed by Drugs.com. Last updated on Mar 10, 2025.

Note: This document provides detailed information about Cytomel Side Effects associated with liothyronine. Some dosage forms listed on this page may not apply specifically to the brand name Cytomel.

Applies to liothyronine: intravenous solution.

Other dosage forms:

• oral tablet

Important warnings This medicine can cause some serious health issues

Intravenous route (solution)

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 or nurse immediately if any of the following side effects occur while taking liothyronine:

More common side effects

• dizziness
• fainting
• fast, slow, or irregular heartbeat

Less common side effects

• bluish color
• blurred vision
• changes in skin color
• chest pain or discomfort
• chest tightness or heaviness
• confusion
• decreased urine output
• dilated neck veins
• dizziness, faintness, or lightheadedness when getting up from a lying or sitting position suddenly
• extreme fatigue
• fever
• headache
• heart stops
• irregular breathing
• nausea
• nervousness
• no breathing
• no pulse or blood pressure
• pain or discomfort in arms, jaw, back or neck
• pain, tenderness, swelling of foot or leg
• pounding in the ears
• shortness of breath
• sweating
• swelling of face, fingers, feet, or lower legs
• troubled breathing
• unconscious
• unusual tiredness or weakness
• vomiting
• weight gain
• wheezing

Symptoms of overdose

• cold clammy skin
• increased bowel movements
• irritability
• lightheadedness
• menstrual changes
• shakiness in legs, arms, hands, feet
• trembling or shaking of hands or feet
• weak pulse

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:

Less common side effects

• twitching

For healthcare professionals

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

General adverse events

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

Cardiovascular

• 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]

Dermatologic

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

Musculoskeletal

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

Gastrointestinal

• Frequency not reported: Diarrhea, vomiting^[Ref]

Immunologic

• Frequency not reported: Hypersensitivity reaction^[Ref]

Local

• Frequency not reported: Phlebitis^[Ref]

Psychiatric

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

Genitourinary

• Frequency not reported: Menstruation irregular^[Ref]

Other

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

Frequently asked questions

• Can I take Cytomel and Synthroid together?
• How long does Cytomel take to start working?
• Does Cytomel help with weight loss?
• How long does Cytomel stay in your system?

Further information

Cytomel side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

Medical Disclaimer