Is Liothyronine the Best Thyroid Medication? When To Use it

Is Liothyronine the Best Thyroid Medication? When To Use it

Liothyronine is a special type of prescription-grade thyroid hormone, it’s also the most powerful thyroid medication that exists. 

People taking liothyronine (especially over traditional medications such as levothyroxine) report significant improvements in their hypothyroid symptoms and quality of life. 

These benefits range from weight loss to reduced rates of depression and more. 

Learn who should consider using liothyronine and how to use it properly with this complete guide: 

What is Liothyronine & What are its Benefits?

Liothyronine is a T3-only thyroid medication and hormone used to treat patients who suffer from hypothyroidism, low thyroid function, or a sluggish thyroid. 

It is a hormone – pure and simple. 

It is also the generic version of the brand-name medication Cytomel (also used to treat hypothyroidism). 

Then why don’t more doctors prescribe it?

In order to understand how T3 works, we need to take a step into some very basic thyroid physiology

Liothyronine otherwise known as T3 is one of the two main thyroid hormones (1) floating around in your blood. 

Since you’re here you probably already know the importance of proper thyroid function in the body, but just in case you can read more about why it’s important to have normal thyroid function here. 

T3 is the sister hormone to T4 but they differ in one very important aspect. 

T4 is an inert or inactive hormone by itself and in order for it to become “activated”, it must be slightly altered (2).

Once it is altered it is changed into T3 – the active thyroid hormone. 

T4 can, therefore, be thought of as a reservoir hormone that your body can draw from to activate thyroid hormone as the need arises. 

The fact that T3 is ACTIVE while T4 is INACTIVE is very important and is why T3 is considered to be MUCH more powerful than T4 (3).

And this is one of the reasons that it’s not as commonly prescribed when compared to other thyroid medications

Liothyronine is felt to be “too strong”, or “too difficult to manage”, or “too dangerous” when compared to T4-only medications such as Synthroid, levothyroxine, and Tirosint

Just because T3 is stronger (about 3-4x stronger than T4 medications like Synthroid) doesn’t mean that it is dangerous. 

If used properly liothyronine can be added safely and effectively to patients with hypothyroidism and generally, they experience significant improvement. 


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Who Should Consider Using T3 Medication

Not everyone who has thyroid disease necessarily needs to use liothyronine in order to feel better. 

Patients who tend to require T3 medications are those who suffer from more serious medical conditions such as systemic inflammation, hormone resistance syndromes such as leptin resistance and insulin resistance, and those with treatment-resistant weight gain. 

Another subset of thyroid patients who may benefit from the use of T3 is those who suffer from low T3 syndrome and other thyroid lab tests which may indicate poor peripheral thyroid conversion (4).

Other patients who are taking T4-only medications such as levothyroxine but who still remain symptomatic may also find relief with small amounts of T3 used in conjunction with their current thyroid medication. 

With these ideas in mind, I’ve compiled a list of patients who may consider the use of T3 in their treatment: 

  1. Patients with low serum levels of free T3 and total T3
  2. Patients with high levels of reverse T3
  3. People who have a “normal” TSH but still remain symptomatic despite taking thyroid medication
  4. Those who suffer from leptin resistance and insulin resistance
  5. People with treatment-resistant weight loss
  6. Patients with treatment-resistant depression and treatment-resistant bipolar disease

This is not an all-inclusive list, but it is a great starting tool. 

When it comes to feeling better starting T3 is only the beginning, more important is the dose that you use.

Liothyronine Dosage Guide

Liothyronine can be used in 2 different ways:

#1. Used in conjunction with other thyroid medications (5), especially T4-only thyroid medications like Synthroid

This is probably the most common way that liothyronine is used nowadays and luckily this sort of therapy is becoming more and more common especially as providers become more comfortable with T3 as a medication. 


#2. Used by itself.

Using T3 by itself is much less common when compared to combining T3 with other thyroid medications. 

Much of this has to do with the current “standard of care” which states that physicians should always use T4 thyroid medication over T3 alternatives. 

But just because this is the “standard” doesn’t mean it doesn’t have utility for certain patients. 

Some patients, especially those with very difficult-to-treat weight loss and hormone imbalances such as leptin resistance, may benefit tremendously from the use of T3 by itself. 

T3-only therapy can be used temporarily to try and “restart” or “kick start” the body back into action or it can be taken long-term as well. 

As long as T3 is used in the correct dosages there shouldn’t be any long-term consequences to its use. 

So what is a safe and effective “dose” for liothyronine?

The answer is not as straightforward as you might think but we can use liothyronine doses to help sort it out. 

Liothyronine comes in the following standard dosages:

  • 5mcg
  • 25mcg
  • 50mcg 

Even though there are 25 and 50mcg doses you will rarely find a provider willing to prescribe a dose that high. 

Instead, most people end up with a dose somewhere between 5 mcg and 20 mcg per day. 

Is there a specific magic dose to look for?

This is where things can get tricky. 

The answer is no. 

Your goal with using Liothyronine (or any other thyroid medication) is to find the amount that you need to reduce your symptoms without causing long term issues

This range is typically somewhere between 5mcg and 20 mcg but it may be higher for some individuals. 

Splitting the Dose Throughout the Day

Liothyronine is different from other thyroid medications because it is active but also because it has a very short half-life. 

The half-life of a medication is a term used to describe how long it “lasts” in your bloodstream before half of the total amount is metabolized. 

Liothyronine has a half-life on the order of 24 hours (6) while levothyroxine has a half-life on the order of 5-7 days (7).

This means Liothyronine isn’t in your system longer than a few days. 

With this in mind, some patients may do better by “splitting” their dosing throughout the day. 

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For most patients, this means taking half of their dose in the morning (with their other thyroid medication) and then the other half later in the afternoon around noon. 

And this makes sense when you consider how the body normally uses hormones. 

Hormones are constantly secreted by functioning glands throughout the day based on the demands of the body. 

No matter how hard we try we will never be able to exactly replicate the dosing schedule that the body uses naturally, but we can get close by taking the hormone at several points throughout the day. 

Obviously, we don’t want to take something like 1 mcg every hour, but taking 5 mcg every 4-6 hours may be a better and more realistic approach. 

Some patients do considerably well with this approach while others may be fine taking all of their T3 in the morning. 

Using Liothyronine for Weight Loss

Liothyronine may cause weight loss but it should not be used as a weight loss medication. 

The use of liothyronine for weight loss in individuals who don’t have thyroid dysfunction may cause unwanted side effects. 

Having said that liothyronine may help with weight loss in patients who have hypothyroidism. 

Some patients taking T4-only thyroid medication may suffer from low T3 syndrome or other problems that interfere with the normal conversion of T4 to T3. 

This may lead to lower than normal serum T3 levels which show up on blood tests (8).

Patients who fall into this category generally have a normal TSH, low T3, and normal to mid-range T4 levels (9).

The addition of T3 to T4 medication such as levothyroxine may help people who fit these criteria. 

T3 may cause weight loss over T4 medications (10) because of how it interacts with fat cells and other hormones in the body. 

T3 directly influences mitochondrial energy production (11) and increases thermogenesis and fat-burning potential. 

If you have low T3 (even if your other thyroid lab studies are “within range”) you may be missing out on these important benefits of T3 in your body. 

Bottom line?

Liothyronine can help with weight loss but it should not be used as a weight loss medication. 

Using Liothyronine to Treat Depression

Liothyronine can also be used to treat depression.

Depression is an obvious and well-known side effect of hypothyroidism – meaning low thyroid levels in the body. 

But what’s interesting is that T3 or liothyronine can be added to antidepressants even in patients with normal thyroid status and still improve mood and cognitive function. 

Unlike weight loss where you shouldn’t use T3 unless you are hypothyroid, small doses of liothyronine can be effective in helping treat depression. 

Some studies have shown that the use of T3 in combination with SSRIs (common antidepressants) enhances the effect of these antidepressants. 

The exact mechanism as to how this helps is not well established, but one of the prevailing theories is that some patients with depression may have subclinical levels (or undetected) of thyroid dysfunction that don’t show up on standard lab tests and may therefore manifest as depressive symptoms. 

The idea is that upon replacing the small deficiency of thyroid hormone the brain has sufficient thyroid hormone and the depression “lifts” or is treated.

Beyond this, T3 has also been shown to directly increase serotoninergic neurotransmission (12) by altering receptor sensitivity to serotonin and also by increasing synaptic concentrations of serotonin. 

Why is this important?

The most important factor is that SSRIs or conventional antidepressants are only successful in treating depression in about 50% of the cases. 

This leaves a huge majority of patients symptomatic even after taking certain medications. 

The concurrent use of T3 to existing SSRIs and other antidepressants may, therefore, be a viable option for many patients who are considered “treatment-resistant” (13).

But what about patients already on thyroid medication but still suffering from depression?

I’ve mentioned previously that T3 is the active thyroid hormone in the body and it seems that the total amount of T3 in brain tissue may influence depressive symptoms (as well as other factors). 

Switching from T4 thyroid medication such as levothyroxine to liothyronine, or simply adding some T3 to their existing T4 medication, has been shown to improve mood and neuropsychological function (14).

One study showed that when patients switched from taking T4 medication to T3 medication they showed an improved mood, an increase in sex hormone binding globulin (likely indicating better thyroid absorption and function), and a slightly higher pulse rate. 

Patients in this study took T4 medication for a set time period and were then converted to T3 thyroid medication, at a rate of 50mcg of T4 to 12.5mcg of T3. 

The study’s conclusion was that there may be something specific to T3 that occurs in the brain tissue which may influence mood and cognition, and this benefit may not be achieved with the use of T4 medication alone. 

Bottom line?

If you are suffering from depression, whether that is from thyroid dysfunction or not, it may be worth considering a trial of T3 therapy or liothyronine as an alternative or complementary treatment to your existing treatment. 

What to Expect when starting T3 medication

Because liothyronine is more powerful than levothyroxine (and other T4 medications) it’s important to talk about expectations when starting the medication. 

Some people believe that upon starting this medication they will immediately lose weight and start feeling better but this is not necessarily the case. 

While it is true that many people who take liothyronine do experience an improvement in their symptoms, in order to get to this level you need to understand some basic rules. 

For starters:

The dose necessary for optimal results will vary based on the individual and you must take some thoughtful time and consideration to get there. 

While dosing, make sure that you follow the thyroid lab tests: TSH, free t3, total t3, and SHBG (sex hormone binding globulin). 

Monitoring lab tests, in addition to your symptoms, will help you get to your optimal dosing. 


When using liothyronine remember the idea of “low and slow” as it relates to titration. 

Because this medication is powerful you always want to start a low dose and titrate up to higher doses in a slow and controlled manner. 

This means incremental increases in the medication every few weeks with periodic checks of serum lab tests. 

Along this same vein is the concept of variable sensitivity to T3 in certain patients: 

Some people tend to be very sensitive to T3 medications. These are patients who may experience jittery sensations or anxiety upon starting even a low dose. 

Sensitive patients tend to require much lower doses than those who are non-sensitive. 

Patients who tend to be sensitive usually know who they are – these are patients who tend to “react” to over-the-counter supplements and other medications. 

But it’s important to identify yourself as either a “sensitive” or a “non-sensitive” patient because of its influence on dosing. 

Non-sensitive patients tend to tolerate moderate to higher doses just fine and is much easier to obtain the correct dosing. 

Following these guidelines will help you find your optimal dose and help you on your way to feeling better. 

Beyond these guidelines, there are also other considerations that should be taken into account when starting liothyronine. 

Hair Loss

The first is the potential for hair loss

Liothyronine, as well as cytomel, may cause a temporary increase in hair loss among certain individuals. 

The good news is that this side effect is almost always temporary (except in a minority of patients) and tends to subside within 3-6 months. 

The bad news is that many patients who suffer from hypothyroidism already experience some degree of hair loss due to the condition itself (along with many other potential factors that you can read more about here). 

Extra hair loss which may be associated with starting liothyronine use may, therefore, be very disturbing to many patients, and rightfully so. 

If you fall into this camp it’s important to realize that this side effect is a temporary and well-known side effect of T3 use. 

Provided you can stick out the side effects for 3-6 months, your hair loss will generally stop and then begin to regrow, even at a rate that was better than starting the medication. 

It is not well understood why hair loss begins in the first place but it may be due to the influence of thyroid hormone on hair follicles themselves. 

It’s also important to realize that hair loss is a well-known side effect of nutrient deficiencies such as iron, biotin, B vitamins, and choline (15).

It’s possible that replacing thyroid hormone with T3 may temporarily exacerbate these deficiencies and lead to an increase in hair loss. 

Other Side Effects

In general, liothyronine is well tolerated provided you dose it in a “low and slow” manner. 

Side effects from this medication tend to occur only when the dose is too high for the individual or for patients who tend to be sensitive. 

With that in mind, the negative side effects of liothyronine use tend to mimic those of hyperthyroidism. 

You can see a list of side effects of using liothyronine below along with the potential cause: 

  • Jittery sensation (usually dose-dependent and from taking too much)
  • Rapid heart rate (an indication you may be taking too much)
  • Nausea (may be secondary to taking the medication on an empty stomach)
  • Hair loss (usually subsides over 3-6 months and is temporary)
  • Stomach pain (may subside when taking medication with a meal)
  • Sensitivity to heat (an indication your dose may be too high)
  • Anxiety (another indication your dose may be too high)

If you experience any of these side effects you should refer to your prescribing Doctor for further recommendations. 

Some patients are also concerned about TSH suppression with the use of liothyronine. 

This side effect is only seen when dosing tends to be on the higher side and it can be avoided by following thyroid lab testing. 

Studies have shown (16) that substituting T3 in place of T4 in pituitary-equivalent dosages (based on the TSH) results in reduced body weight and better cellular thyroid action on lipid metabolism without negative side effects. 

Final Considerations

Liothyronine is a very powerful and strong thyroid medication that is used to treat people who suffer from hypothyroidism. 

This medication differs from other thyroid medications in that it contains the active thyroid hormone T3. 

This medication, therefore, does not need to be “activated” by the body and begins working almost immediately. 

Because of these unique properties T3 can be used either by itself or in conjunction with other thyroid medications and may help treat difficult conditions such as treatment-resistant depression and treatment-resistant weight loss. 

Dosing should be titrated low and slow and dosing should be individualized while following serum thyroid lab tests. 

Side effects tend to be minimal if the medication is used correctly and if titrated in this way. 

Now I want to hear from you:

Are you using liothyronine?

Has it helped treat your thyroid disease?

What dose are you currently at?

Leave your comments below! 

Scientific References

















what you should know about liothyronine (T3 thyroid medication)

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About Dr. Westin Childs

Hey! I'm Westin Childs D.O. (former Osteopathic Physician). I don't practice medicine anymore and instead specialize in helping people like YOU who have thyroid problems, hormone imbalances, and weight loss resistance. I love to write and share what I've learned over the years. I also happen to formulate the best supplements on the market (well, at least in my opinion!) and I'm proud to say that over 80,000+ people have used them over the last 7 years. You can read more about my own personal health journey and why I am so passionate about what I do.

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