Cytomel: History, Medical Use, Dosage, Side Effects and More

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Hypothyroidism is a common disorder indicated by the inability of the thyroid to produce important hormones.

According to some estimates, one in 300 people in the United States have hypothyroidism. The prevalence of this disorder is more common in women than in men.

Real figures could be even higher as 13 million Americans have undiagnosed hypothyroidism, according to this study. Treatment options for the disorder revolve around the intake of medications that stimulate the thyroid to produce hormones.

Cytomel is one of these medications and throughout this post, you are going to learn more about its efficacy, potential side effects and interactions, history, and other vital information.


Cytomel is a brand name of liothyronine sodium, a synthetic or man-made version of a hormone called triiodothyronine (T3) which is produced by a thyroid gland.

Even though to most of us it may seem like Cytomel is some modern age medication, it has been around for decades. The history of this medicine leads us back to the early 20th century when the thyroid’s secretion of an idone-containing substance was examined.

In 1914, a Professor of Psychological Chemistry at the Mayo Clinic, Edward Kendall, isolated crystalline thyroxine (T). Kendall discovered it exerted same effects as the thyroid extract from which it derived.

A decade later, in 1926, Charles R. Harrington defined the chemical formula of T and synthesized the hormone subsequently. This was a major discovery primarily because of the ability to synthesize sodium l-thyroxine and allow oral absorption made thyroid replacement cheap and safe.

At that point, the carcinogenic effect of a synthetic version of T was lower compared to thyroid extracts. As a result, science kind of stalled in this department for quite some time as scientists struggled to overcome this enigma.

The breakthrough was made in 1952 when Rosalind Pitt-Rivers and her postdoctoral fellow Jack Gross discovered and synthesized triiodothyronine (T3) and confirmed it was biologically more active than T. Four years later, in May 1956, the FDA approved a synthetic version of T3, liothyronine.

Medical use

The medication is approved for use in adults, children, and infants. Cytomel is primarily used for treating low thyroid function i.e. hypothyroidism. According to, Underactive thyroid can occur either naturally or due to the injury of the thyroid gland by radiation or certain medications.

Liothyronine may also be recommended to patients with myxedema coma due to a rapid onset of action, an earlier beneficial effect on neuropsychiatric symptoms, and significant clinical improvements within 24 hours. Myxedema coma is a severe and life-threatening form of decompensated hypothyroidism[i].

A person with this condition may have lab values identical to those with hypothyroidism. However, a stressful event can bring about the myxedema coma state.

In addition to hypothyroidism, other medical uses of this medication include prevention and treatment of distinct types of goiters and thyroid cancer as well as for certain thyroid diagnostic tests. Cytomel is also used in cases when patients are allergic to other thyroid medicines.

Occasionally, a healthcare provider may recommend off-label use of Cytomel for issues such as treating depression.

Low-dose of the medication improves symptoms of depression in patients with normal thyroid function who do not experience relief from standard antidepressants. In fact, when was added to existing medications, liothyronine led to remission in 24% of patients who participated in a large depression trial[ii].


When it comes to the dosage of Cytomel there is no “one size fits all” rule. Instead, the dosage is individualized according to a patient’s response in laboratory tests. Cytomel comes in the form of tablets; hence it is taken by mouth. In most cases, patients take the drug once a day with or without food, as suggested by a healthcare provider.

It goes without saying that patients should always take medications, including Cytomel according to doctor’s instructions. You should never, under any circumstances, change the dosage or discontinue using the drug without consulting your physician.

Below, you can see typical dosage recommendations for different health problems addressed with Cytomel.

Mild hypothyroidism

The starting dosage is 25mcg a day, but every 1-2 weeks a physician may increase the dosage by up to 25mcg. The maintenance dose, in most cases, is 25-75mcg per day. Don’t forget that your daily dose is set according to your condition!


In this case, the recommended starting dose is 5mcg daily, but it may be increased by 5-10mcg every 1-2 weeks. When a patient reaches 25mcg per day, a doctor may increase the dosage by 5-25mcg every 1-2 weeks until a patient shows a satisfactory therapeutic response. The typical maintenance dose is 50-100mcg a day.

Congenital hypothyroidism

For patients, infants primarily, with congenital hypothyroidism, the starting dosage is 5mcg daily with a 5mcg increment every 3-4 days until a patient exhibits the desired response. Infants who are only a few months old may only need 20mcg a day maintenance dose while 1-year-olds may require a dosage of 50mcg daily. Children older than 3 may require a full adult dose of Cytomel.

Non-toxic goiter

The starting dosage is similar to those in other conditions, 5mcg a day. Every 1-2 weeks, the physician may recommend increasing the dose by 5-10mcg until a patient reaches 25mcg a day. In that case, a doctor may advise increasing dosage by 12.5-25mcg a day. A standard maintenance dose of Cytomel is 75mcg on a daily basis.

How it works?

Cytomel works to replace or provide more thyroid hormone, which is usually produced by a thyroid gland (see WebMD’s explanation for more information about this.) The body requires thyroid hormone to maintain the adequate metabolic rate of the tissues. Liothyronine works fast to restore the normal function of body tissues and organs but must be taken on a daily basis to remain effective.

The thyroid gland produces two different types of hormones T3 and T4 (levothyroxine).

Despite the fact that T3 is more active than T4, the thyroid produces the latter in greater amounts. Although the body itself can convert T4 into T3 when needed, in persons with hypothyroidism that is not entirely possible. To improve one’s health and allow a patient to manage symptoms, doctors recommend Cytomel to replace or provide the much-needed T3 hormone.

Other forms of treatments combine both T3 and T4, but they are not suitable for most people due to a high risk of allergic effects.

On the other hand, synthetic thyroid hormones like Cytomel are less likely to induce allergic reaction due to the fact they are not made of the animal thyroid. Additionally, Cytomel allows more precise control of patient’s thyroid levels.


Patients are advised to inform their healthcare providers about other medications they are taking before they start using Cytomel.

According to 287 drugs are known to interact with this medication. Mentioning other medicines to your doctor is the best way to decrease the risk of interactions. The same applies to cases when patients are already using Cytomel but their physician is about to prescribe treatment for some other condition.

Common medications known for interacting with Cytomel include:

  • Alprazolam (Xanax)
  • Amphetamine/dextroamphetamine (Adderall)
  • Antacids containing aluminum or calcium
  • Anti-diabetes medications (insulin, metformin, glyburide)
  • Birth control pills
  • Bupropion (Wellbutrin XL)
  • Calcium polystyrene
  • Cholecalciferol (Vitamin D3)
  • Clonazepam
  • Cyanocobalamin (Vitamin B12)
  • Diet pills
  • Digoxin
  • Duloxetine (Cymbalta)
  • Esomeprazole (Nexium)
  • Estrogens
  • Gabapentin
  • Iron supplements
  • Lamotrigine (Lamictal)
  • Levothyroxine (Levoxyl, Synthroid)
  • Metformin
  • Montelukast (Singulair)
  • Omeprazole
  • Prednisone
  • Topiramate (Topamax)
  • Tramadol
  • Trazodone
  • Tricyclic antidepressants (imipramine, amitriptyline)
  • Warfarin

Cytomel may also interact with diseases or conditions such as adrenal insufficiency, diabetes, seizures, cardiovascular disease, and thyrotoxicosis (excess of thyroid hormone in the body).

Side effects

No medication comes without side effects and Cytomel is not an exception to this rule. The most common side effects associated with intake of liothyronine are as follows:

  • Appetite changes
  • Arm, back or jaw pain
  • Changes in menstrual periods
  • Chest pain or discomfort
  • Chest tightness or heaviness
  • Cold clammy skin
  • Confusion
  • Decreased urine output
  • Diarrhea
  • Difficulty breathing
  • Dilated neck veins
  • Dizziness
  • Excessive sweating, including face, fingers, feet, or lower legs
  • Extreme fatigue
  • Fainting
  • Fast, slow, pounding, or irregular heartbeat or pulse
  • Fever
  • Hand tremors
  • Headache
  • Increased bowel movements
  • Irregular breathing
  • Irritability or mood swings
  • Leg cramps
  • Lightheadedness
  • Nausea and vomiting
  • Nervousness
  • Sensitivity to heat
  • Shortness of breath
  • Trouble sleeping
  • Weak pulse
  • Weight gain
  • Weight loss
  • Wheezing

If you experience symptoms mentioned above, contact your healthcare provider or go to the emergency room if they feel really serious.


Although Cytomel was never a part of some big scandal, some controversies still surround it.

For example, the active form of thyroid administration can lead to fluctuations in FT3 levels, thus increasing the risk of cardiovascular effects compared to T4.

Although it works quickly, it can be difficult to maintain a consistent effect, which is why it is usually recommended to patients who are intolerant to T4, according to this website. Due to inconsistency in attaining favorable therapeutic effects with one specific dose, T3 is regarded as unreliable.

Cytomel has become a controversial subject due to its non-medicinal uses. An increasing number of bodybuilders and other individuals use the medication as a steroid. In fact, it is one of the most commonly used steroids to promote fat loss and accelerate metabolic rate for better performance.

Faster loss of fat mass allows bodybuilders and similar individuals to increase the size of their muscles and define their shape.


Cytomel is a medication used to treat hypothyroidism and other thyroid-related problems. Off-label uses are also possible, primarily in patients with depression. The medication works to replace or promote the production of a T3 hormone that thyroid gland doesn’t produce properly in some people.

Dosages are individualized according to every patient’s laboratory findings. Different conditions require different doses. At the same time, the doctor may prescribe increased dosage every 1-2 weeks. Cytomel can interact with different medications and diseases and it is associated with a number of side effects.


[i] Mathew V, Misgar RA, Ghosh S, et al. Myxedema Coma: A New Look into an Old Crisis. Journal of Thyroid Research. 2011;2011:493462. doi:10.4061/2011/493462.

[ii] Nierenberg AA, Fava M, Trivedi MH, et al. A comparison of lithium and T3 augmentation following two failed medication treatments for depression: A STAR*D report. The American Journal of Psychiatry, Volume 163, Issue 9, September 2006, 1519-1530, Doi: 10.1176/ajp.2006.163.9.1519

1 Comment
  1. Reply
    Tigerz June 23, 2018 at 11:09 am

    From a family history of thyroid problems, we’ve experienced the range of problems. From hyper to hypo, goiters etc. The only way to adjust your dose, carry a thermometer. If your temp falls below 97.8, you are hypothyroid. Can’t figure out how much T3 to take? Take your temperature. We have found our perfect dose to be 50mcg T3 twice a day with 130 mg WP thyroid twice a day. That will sound like a lot to most doctors but most doctors are under treating thyroids. Every now and then your temp will stay above 97.8 without thyroid. That just means your body wants a short break. Also, if you’re running a low grade fever you will not need additional thyroid. What does this all mean? TAKE YOUR TEMPERATURE 🤒

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