T3 Supplements vs T3 Medications: How & When to use Them

T3 Supplements vs T3 Medications: How & When to use Them

Are you looking to boost your T3 thyroid hormone levels?

Maybe you know that T3 is responsible for managing your energy levels, or maybe you know how important it is for your metabolism. 

Either way, there are several T3 supplements that you can use to increase serum T3 levels.  

Use this guide to help you improve your thyroid function and increase the T3 in your body. 

Let’s dive in: 

What Are T3 Supplements?

T3 is the active thyroid hormone in your body.

It is known as triiodothyronine and should not be confused with T4 which is known as thyroxine.

When referring to thyroid hormones it’s easier to refer to them as either T3 or T4.

But what’s the difference between T3 and T4?

T3 is the active thyroid hormone in your body.

That means T3 is responsible for ALL of the effects that thyroid hormone is involved within your body:

After reading this list it should be obvious why you would want to boost your T3 levels, right?

And we are going to talk about how to supplement with T3 both naturally and with medications, but we are getting ahead of ourselves.

Why is T3 different than T4?

T4 is the STORAGE form of thyroid hormone in your body.

T4 by itself doesn’t have any activity but instead acts as a reservoir source for T3 thyroid hormone.

Your body holds onto T4 thyroid hormone in the body and can convert T4 into T3 (by knocking off an iodine moiety) to active thyroid hormone.

Your body does this to allow for the exact amount of thyroid hormone in the right tissue at the right time.

It’s an evolutionary mechanism that works well… when it is working.

In order for this process to work correctly, you need to have adequate amounts of T4 thyroid hormone and you need perfect T4 to T3 conversion.

Unfortunately, many things interfere with both of these processes which is why boosting your T3 may be necessary and helpful.

So where do T3 supplements fit in?

It turns out that you can take targeted supplements to BOOST or increase your T3 levels in the blood and in your body.

Boosting T3 levels allows for MORE of the positive effects listed above (more weight loss, more energy, more hair growth, etc.).

But how do you do it?

Increasing T3 with Zinc and Selenium

You have a couple of options if you want to boost your T3 levels. 


You can boost the conversion process we touched on above.

If you have adequate amounts of T4 in your serum, then boosting the conversion will help liberate more T3 and more active thyroid hormones.

But in order for this step to work you need to have adequate amounts of T4 thyroid hormone reservoir in the body.

This leads us to the second option:

You can boost your total amount of thyroid hormone directly.

Many factors and nutrients are involved in thyroid hormone production (many nutrients that you may be deficient in).

By taking targeted supplements you can provide the right substrate to your body which will allow for optimal thyroid hormone production.

In reality, if you are serious about your thyroid function, you will probably want to do both simultaneously.

There is also a third way to increase your T3…

You can simply take T3 thyroid medication (note that this is a prescription medication that will require a doctor’s prescription). 

This is obviously the easiest way to boost T3 thyroid hormone in your body, but it is not without side effects and it is something we will touch on later in this post.


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T4 to T3 Conversion & Its Impact on T3

So how do you boost thyroid hormone conversion?

In this section you will really want to focus on 2 things:

1) Boosting T4 to T3 conversion (8)


2) Increased cellular sensitivity to the nuclear thyroid hormone receptor (9)

You can see a complete outline of what happens from the time that thyroid hormone is produced from your thyroid gland till the time that it hits the nucleus of your cell and activates genetic transcription (alters genetic function). 

a diagram of the thyroid gland with t3 and rt3 levels shown as well as various factors that influence the conversion of both of these thyroid hormones.

This image should give you a great idea of what we are going to focus on here, but let me also add a bit of clinical experience to help guide you in your supplementation. 

The first thing you may notice is that there are several supplements that can help boost T4 to T3 conversion:

Namely zinc and selenium.

Zinc is a micronutrient that MANY patients are deficient in.

So supplementing with zinc is particularly helpful (especially if you don’t eat an organic, whole food-based diet).

Zinc is a potent anti-inflammatory agent (10), can help balance the immune system (11), and is required for optimal hair/nail growth.

Supplementing with zinc is a great idea to boost your thyroid conversion (12) but you should take a couple of notes when considering supplementation:

1) Make sure that you are taking a high enough dose.

2) Make sure that you are taking the right form of zinc.

3) Make sure that you take it in tandem with other supplements and for a long enough length of time.

When supplementing with zinc you will want to use 30-60mg per day. 

You will want to make sure that your zinc is bound to picolinic acid because this form is highly absorbable.

And you will want to make sure you are taking it for at least 3+ months to ensure tissue level saturation.

Much like zinc, selenium is also a micronutrient that many patients are deficient in. 

And again, much like zinc, selenium can help boost T4 to T3 conversion.

But selenium is also quite potent at balancing the immune system, especially in patients who already have thyroid issues – especially Hashimoto’s thyroiditis.

Taking selenium, especially with zinc and iodine, can help improve the function of your thyroid, boost conversion and help promote proper thyroid hormone production (13).

When considering selenium supplementation consider these points: 

1) You should be supplementing at a dose of 100-200mcg per day.

2) Your selenium should be bound to methionine for superior absorption.

3) If you are taking iodine you should also take it with selenium (preferably in a combined supplement).

4) Take both zinc and selenium for at least 3+ months and together if possible.

You can find a combination of zinc and selenium in the right doses in this supplement.

If you use my recommended product and brand it contains both zinc plus selenium along with other nutrients that have been shown to help with thyroid hormone conversion, biosynthesis, and cellular sensitivity. 

Inflammation and Its Impact on T3

You may have noticed that other factors (aside from supplementation) can alter thyroid hormone conversion. 

What I am referring to here is inflammation: 

diagram which outlines the impact that inflammation and immune dysregulation have on the HPT axis, thyroid conversion, and thyroid receptor function.

Inflammation will directly reduce your T4 to T3 conversion (14), even in the face of taking supplements like zinc and selenium. 

I only mentioned it here because if you are serious about boosting your T3 levels then you need to make sure that you manage inflammatory levels.

Reducing your inflammation can range from easy to complex but either way, some basic rules still apply:

  • Make sure that you are eating an inflammatory, whole food-based diet
  • Make sure that you are taking anti-inflammatory supplements
  • Make sure that your gender-specific sex hormone are balanced (that means testosterone, estrogen, and progesterone)
  • Make sure that your insulin and leptin levels are under control

All of these factors influence inflammation and may alter your thyroid hormone conversion (and interfere with other functions in your body). 

Increasing T3 Levels Directly from the Thyroid Gland

Another way to promote higher T3 levels is to increase thyroid hormone production from the thyroid gland. 

You can see from the image above that at least 13 nutrients are required for proper thyroid hormone production.

Each step of thyroid hormone creation requires these nutrients.

But several of them tend to be more important than others, and those are the ones that we are going to discuss in this section.

The only downside to improving thyroid hormone production is that you have less control over what your body will produce.

What that means is that you can’t specifically target the production of T3 thyroid hormone.

Instead, by taking these supplements, you will most likely increase BOTH T4 and T3 thyroid hormone levels.

Because of this, it’s usually almost always beneficial to simultaneously take medications that increase T4 to T3 conversion as you boost both thyroid hormone levels in the body. 

But which supplements should you take to boost thyroid hormone production?

In my experience these are the nutrients that work best:

I chose these supplements for the following reason:

1) Why Iodine?

Iodine is a critical component of thyroid hormone production. In fact, the difference between T4 and T3 is due to the iodine moiety.

So 3 iodine molecules are required for the creation of T3 thyroid hormone.

But here’s one of the main benefits of using Iodine. 

Not only is iodine required for proper thyroid hormone production, but it’s also commonly displaced by other halides that humans come into contact with.

These halides share the same number of electrons on their outer shell which means that from a polarity standpoint they can actually knock off iodine moieties and blunt the effectiveness of thyroid hormone in the body.

The halides I am talking about include bromide, chloride, and fluoride.

Bromide is in various foods that we eat such as bread and even soda.

There have even been case studies showing bromide toxicity (15) from consuming too many of these foods.

Fluoride is in fluoridated water (which you consume if you are drinking tap water). 

Studies have shown reduced T3 levels and altered TSH (16) levels in patients drinking fluoridated water. 

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The point is that these halides can compete for binding with iodine and interfere with thyroid hormone function. 

So how does iodine fit in here?

Increasing the levels of iodine in your serum will cause preferential binding of iodine over these halides and restore the functionality of your thyroid hormone. 

Displacing these halides may result in symptoms such as bromoderma, however which is why I recommend taking selenium in combination with iodine if you choose to use this supplement. 

How to use Iodine:

I recommend using this supplement and starting with 1 drop per day. 

As tolerated you can increase the dose up to 12.5mg per day. 

2) Why Vitamin A & Vitamin E?

Vitamin A and Vitamin E are both fat-soluble vitamins (17).

Fat-soluble nutrients are critical to multiple functions (including cellular functions) and are commonly found in nutritional foods.

Unfortunately, with the standard American diet (18), many patients have suboptimal fat-soluble vitamins.

As a result, supplementing with these fat-soluble vitamins is necessary and helpful in the right amount.

Vitamin A is particularly helpful because it can help promote cellular sensitivity to thyroid hormone in addition to being required for proper thyroid hormone production.

How to use Vitamin E & Vitamin A:

Vitamin E – start with 1-2 capsules per day (take with a fatty meal to increase absorption). 

Vitamin A – Use 1 drop per day (about 5,000 IU) in a micellized form to increase absorption. 

3) Why iron?

Lastly, I wanted to give an honorable mention to Iron. 

Iron is required for proper thyroid hormone production BUT it is required in *just the right amount, which is why it is marked with an asterisk.

Before supplementing with iron I recommend that you read this post in detail to make sure that you are indeed suboptimal.

Replacing iron can dramatically improve thyroid function and reduce the symptoms of hypothyroidism so it is certainly worth evaluating your levels.

As recommended above, for optimal results, make sure you combine these supplement classes together to boost thyroid hormone conversion, thyroid hormone production and increase cellular sensitivity to thyroid hormone as well.

Will T3 Supplements Help You Lose Weight?

One of the main reasons that people want to know about T3 supplements is because of their effect on metabolism and, therefore, weight.

T3 thyroid hormone has a major influence on basal metabolic rate and, therefore, your resting metabolic rate or resting energy expenditure.

What you may not realize is that when it comes to weight loss there is no greater factor in determining how much weight you will lose than your metabolism.

Exercise by itself only accounts for a fraction of your total daily caloric burn.

Compare that to your resting metabolism which represents about 90% of your total energy expenditure in the form of calories.

And T3 directly influences this number through its metabolic effects on your mitochondria.

Your mitochondria create the majority of energy in the form of ATP for each of your cells, and this energy production is important to produce muscle contraction, etc. which results in caloric burn.

So to answer the question – do T3 supplements help with weight loss, the answer is yes and maybe.

If you have nutrient deficiencies, or if your thyroid function is suboptimal then yes these supplements can help boost your metabolism and help with weight loss.

If weight loss is your goal then supplementing directly with T3 thyroid hormone is often more potent than using just supplements alone (really they should all be used together, however).

We will discuss how and when to consider using T3 medication below. 

Do T3 Supplements Have Side Effects?

The good news about supplementing with the nutrients listed above is that they are generally VERY well tolerated.

While they tend to be somewhat less potent than T3-containing prescription medications, they are very well tolerated and often do not carry any side effects.

Most side effects can be attributed to an intestinal intolerance (GI upset) which is readily fixed by taking these nutrients with meals.

T3 thyroid hormone prescriptions, on the other hand, tend to have other side effects if not used correctly.

Increasing T3 with Prescription T3 Thyroid Medications

Another way that you can supplement with T3 thyroid hormone is by directly taking the T3 thyroid hormone itself.

This T3 thyroid hormone is available in prescription form from your Doctor (compared to the supplements and nutrients listed above which are available over the counter).

Generally speaking, the more tightly regulated the supplement or medication then the more potent or efficacious it is.

Supplementing directly with T3 thyroid hormone is probably the most effective way to increase your T3 levels, but it can also be difficult to acquire from your regular physician.

This is mostly because providers aren’t willing to prescribe T3-containing medications and are not comfortable or used to prescribing these medications.

Having said that, you should still understand the basics of T3 thyroid hormone if you consider supplementing.


Cytomel and liothyronine are what I consider to be immediate-release formulations of T3 thyroid hormone.

These medications should be differentiated from other forms of thyroid hormone like levothyroxine and Synthroid which contain T4-only thyroid hormone.

These medications are rapidly absorbed and usually reach peak serum levels within 2-3 hours of ingestion.

Occasionally patients do not respond well to these forms of T3 due to the serum rush of T3 and its effects on myocardial heart tissue.

T3 directly stimulates the calcium channels in your cardiac tissues which may lead to increased force and rate of contraction leading to the symptoms of heart palpitations or tachycardia.

Usually, by simply delaying the release of T3 thyroid hormone into the serum you can avoid these negative side effects… 

Sustained release T3

Sustained release T3 represents T3 thyroid hormone that is bound to a glue-like substance known as cellulose.

The cellulose delays the absorption of T3 into the body effectively creating a “time-released” or “sustained release” preparation of T3 thyroid hormone.

Some patients don’t do well on SR T3 formulations due to the delayed absorption which may effectively reduce the total dose received of thyroid hormone.

SR T3 must be acquired from a compounding pharmacy and is a prescription medication. 

Natural Desiccated thyroid hormone

T3 thyroid hormone is also found in smaller doses in the prescription medication of Natural desiccated thyroid hormone (NDT). 

NDT contains both T4 and T3 thyroid hormone which makes it less effective for weight loss and increasing metabolism than T3 alone, but it will be mentioned here for completeness.

Prescription T3 medication side effects

Because T3 medications provide T3 thyroid hormone directly they may cause symptoms.

The most common symptoms of T3 supplementation include:

  • Heart palpitations
  • Rapid heart rate
  • Jittery sensation
  • Temporary hair loss
  • Flushing sensation
  • Warm body temperature
  • Hot flashes

These symptoms usually occur as a result of too much T3 thyroid hormone in the serum and may be a result of “flooding” the system. 

Usually by simply delaying the rate at which the T3 is absorbed many of these symptoms will subside over time.

While using T3 supplements it’s best to monitor both your resting heart rate and basal body temperature to gauge just how well your body is tolerating the medication/supplement. 

If your body temperature and heart rate increase beyond 80 beats per minute or more than 98.6 degrees F, then that is an indication that your dose is too high.

You can learn more about how to use Cytomel and liothyronine in this post (especially if you are interested in weight loss).

Recap & Final thoughts

T3 supplements can help boost your metabolism, increase weight loss and help improve your thyroid function. 

Having said that it is important to realize HOW and WHEN to use these supplements to boost your thyroid function. 

Using targeted supplements can help improve your T4 to T3 conversion and improve the production of thyroid hormone in your body leading to higher T3 levels. 

On the other hand, you can also directly add T3 thyroid hormone to your regimen in the form of prescription medication. 

T3 thyroid supplements tend to be well tolerated when compared to T3 thyroid medications, but both can be used safely as long as your provider knows what they are doing. 

Now it’s your turn:

Are you using supplements to boost your T3 levels? 

Are they working for you?

Why or why not?

Leave your comments below! 

#1. https://www.ncbi.nlm.nih.gov/pubmed/11174855

#2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4044302/

#3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4037849/

#4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC209345/

#5. https://www.ncbi.nlm.nih.gov/pubmed/274725

#6. https://www.ncbi.nlm.nih.gov/pubmed/18728176

#7. https://www.ncbi.nlm.nih.gov/pubmed/23707189

#8. https://www.ncbi.nlm.nih.gov/books/NBK28/

#9. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC329808/

#10. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4429650/

#11. https://www.ncbi.nlm.nih.gov/pubmed/12142956

#12. https://www.ncbi.nlm.nih.gov/pubmed/8157857

#13. https://www.ncbi.nlm.nih.gov/pubmed/20883174

#14. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3978663/

#15. https://www.ncbi.nlm.nih.gov/pubmed/9140329

#16. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3890436/

#17. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3997530/

#18. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4074336/

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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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#1. Get my free thyroid downloads, resources, and PDFs here.

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