T2 is quickly gaining popularity among thyroid patients for its benefits on metabolism, weight management, and cholesterol levels.
And, as a result, a lot of other thyroid patients are taking notice and have been asking questions:
What is T2? Is it safe? What are the side effects?
Well, today, we are going to talk about just that.
Over the last year or so, over 15,000-20,000 thyroid patients have used my T2 supplement so I’ve been able to collect a lot of data about its potential positive and negative side effects.
And it’s these side effects that I want to share with you today so you can determine if T2 is something that you should consider taking.
First, let’s start with the basics:
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What is T2 Thyroid Hormone?
What is T2?
T2, known as 3, 5 diiodo-l-thyronine is a thyroid hormone much like T4 and T3.
The primary difference between T2 and these hormones has to do with their function and activity on the thyroid hormone receptor.
T4 (found in levothyroxine and Synthroid) is primarily used as a reservoir hormone for the creation of T3 (1).
T3 (found in Cytomel and liothyronine) is the strongest thyroid hormone and has the most activity on the thyroid hormone receptor (2).
And T2 (found in over-the-counter supplements) seems to enhance the effect of T3 thyroid hormone while also exerting some direct thyroid hormone activity (3).
Each thyroid hormone does something different, which is why I believe that most hypothyroid patients want to take a combination of all 3 if possible.
While this may be the first time you’re hearing about T2, it’s not a new thyroid hormone and it’s been around for decades.
Researchers and scientists have known about T2 for a long time and many of you listening to this have probably taken it without realizing it.
This is because T2 is found in small amounts in NDT thyroid medications like Armour thyroid, NP thyroid, and Adthyza.
It just so happens that over the last 10-15 years, T2 has been the subject of intense research due to its effects on metabolism and fat loss, where it’s being studied as a potential weight loss treatment (4).
Thyroid patients who want better thyroid hormone management and better weight loss find the prospect of using T2 very enticing.
Is T2 Thyroid Hormone Safe?
Whenever someone hears about T2 for the first time, they almost reflexively want to know whether or not it’s safe.
They assume that because they haven’t heard about it, there must be something wrong with it.
Most doctors aren’t aware of it simply because it’s not really discussed by pharmaceutical companies and because the research on this hormone is relatively new, not because it doesn’t work or because it isn’t safe.
Believe it or not, it’s very difficult for doctors to keep up with the latest research which is why most of them are, on average, 17 years behind (5).
But as to the question of safety, here’s what we know:
#1. For starters, there’s no reason to automatically assume that T2 is harmful because we know it’s created naturally by the body.
So even as you are listening to this right now, your body is creating some amount of T2 which is doing its job.
#2. Thyroid patients have been using T2 for over 70 years because it’s naturally found in NDT thyroid medications.
If there was a safety problem with T2, we would have seen it by now.
#3. Over-the-counter T2 supplements have been available for a long time as well.
Until recently, these were primarily marketed at bodybuilders and included in weight loss supplements because of T2’s effect on metabolism.
Again, if there were a problem, we would have seen it by now.
When you consider these factors, plus available research studies, we can say with a high degree of certainty that T2 is not harmful.
What are the Side effects?
Having said that, no hormone and no medication is completely free of side effects and T2 is no exception.
While most people who take it only experience positive side effects, there are some who experience negative side effects.
And like other thyroid hormones, the side effects of T2 are primarily dose-dependent.
In other words, the more you take, the more likely you are to experience side effects.
This is because the body is used to some amount of T2 so it knows how to metabolize and handle it.
This is different from pharmaceutical medications because many of these compounds are completely foreign to the body, so in some cases, any amount is enough to cause side effects.
That’s typically not the case with T2, as most thyroid patients who take it are able to adjust their dose to experience positive side effects without negative ones.
Based on my experience helping over 10,000 thyroid patients use T2, here’s what I’ve found.
Roughly 70-75% of thyroid patients see some sort of positive experience.
About 10-15% experience no discernable benefit.
And about 10-15% experience some minor negative symptoms.
As far as positive symptoms go, thyroid patients have reported the following:
- Improved body temperature
- Easier weight loss
- More energy
- Feeling more balanced
- And better thyroid symptom control overall
Because T2 primarily targets metabolism and cellular ATP production, this is exactly what we would expect.
As far as negative symptoms go, some thyroid patients have reported the following:
- Jittery sensation
- Dizziness
- Nervous energy
- Increased heart rate
- Palpitations
- Insomnia
- And one person reported hair loss
These side effects tend to be quite rare and are typically dose-dependent, meaning they can be managed simply by reducing how much you are taking.
And because they all go away once you stop taking T2, there’s pretty much no harm in giving it a try.
Will T2 Cause Heart Problems or Heart Enlargement?
Some providers and thyroid experts have been making the claim that T2 is unsafe because there are studies showing that it can cause cardiac enlargement.
Knowing this, doesn’t it mean that T2 should be avoided at all costs?!
Nah, because when you look at the study citing this side effect, it becomes clear why it occurred.
First off, here’s the study that these providers are citing: https://jme.bioscientifica.com/view/journals/jme/19/2/137.xml
Which is also referenced here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4272398/
But let’s break this down because it’s really not concerning once you understand how this study was created and what it really showed.
We know a fair amount about T2 thyroid hormone and how it works, but we don’t know exactly how powerful it is, especially when compared to other thyroid hormones like T3.
So the researchers of this study devised a way to compare a supraphysiologic dose of T3 to a supraphysiologic dose of T2 with the intent to compare outcomes.
For those who may be unaware of the language used here, the term supraphysiologic just means a dose that is much higher than what would be considered normal.
Let me make this clear:
The researchers intentionally used hyperthyroid doses of BOTH hormones in order to assess how powerful T2 is compared to T3.
And they found what you’d probably expect:
Supraphysiologic doses of T3 (those doses that are much higher than what you’d find normally occurring in the body) resulted in hyperthyroid-like symptoms including liver problems, heart problems, and more.
In other words, they forcibly made the mice hyperthyroid and saw exactly what they would expect.
Then they took the dose they used of T3 to get those side effects and multiplied it by 80 (no, that’s not a typo), and evaluated what happened in the mice.
They found that the dose of T2, which was 80 times that of T3, resulted in all of the same symptoms, including the symptom of cardiac enlargement.
But does this surprise anyone?
It shouldn’t.
You would get the exact same results if you used a similar dose of T4 (levothyroxine) or any other thyroid hormone.
So did this study show that T2 causes heart problems? Well, technically, but only if the dose used is 80 times that of what is already considered an already mega dose of T3.
The only real conclusion you can draw from this study is that T2 is a powerful thyroid hormone that definitely exerts an impact on the body.
But, just like any other thyroid hormone that exists, if used irresponsibly, it can lead to problems.
Before we move on, let’s put some of this into perspective so I can give you an idea of how truly ridiculous this claim is.
If we look at humans (which is what we care about, not mice), the standard dose of T3 is usually around 5 mcg to 20 mcg.
This type of dose isn’t even considered to be supraphysiologic, it’s actually considered to be physiologic, but let’s use it just to illustrate the point.
If we use the same doses of T2 used in the study cited above, then that means if you were taking 5 mcg of T3, you’d need 400 mcg of T2 to get a roughly equal impact on your body as that small dose of T3.
If you were taking 20 mcg, the dose of T2 you’d need to get there would be 1,600 mcg.
And even at these high doses (400 mcg to 1,600 mcg), you still wouldn’t push yourself into the hyperthyroid range because we know that the 5-20 mcg of T3 doses do NOT cause this issue.
If you consider that most people who take T2 are using a dose of 100 mcg (200 mcg at most) per day, they are about 1/4 of that 400 mcg dose (which is on the lower end).
And they are even farther away from the 1,600 mcg dose.
Is there any chance of experiencing cardiac enlargement at these doses? No way.
I’ve personally seen one person experience cardiac enlargement when using T3 and that symptom didn’t start to become apparent until T3 dosing hit over 500 mcg per day (I didn’t provide this dose, they came to me on this dose and we lowered it).
That means, in reality, you’d probably need a truly astronomical dose of T2 to experience cardiac enlargement, at least based on the only case of true cardiac enlargement that I’ve seen from T3 dosing.
Not only would this not be economical, but you’d basically have to take an entire bottle of Essential T2 daily for 4-8 weeks to get there.
The bottom line? T2 is no more likely to cause cardiac enlargement than T3 is, and neither will cause problems if they are dosed correctly.
What’s a Safe dose?
Since most side effects (both positive and negative) are dose-dependent, it’s important to talk about how much should be used.
To do that, we have to use a combination of anecdotal experience as well as some information from available studies.
Right now, we know that a safe dose of T2 is anything less than 300 mcg per day.
Problems start to arise when dosing increases above 300mcg and serious problems start to arise when dosing exceeds 800mcg per day (6).
Fortunately, it’s very difficult to get to these doses, because most supplements are dosed in the 100 mcg range so you’d need to take something like 8 capsules per day for months at a time to experience these problems.
Avoiding toxicity is pretty easy, but what’s difficult is figuring out the minimum effective dose that should be taken.
In a perfect world, I’d be able to tell you exactly how much T2 you should take so that it provides therapeutic benefits without causing any issues whatsoever just like your thyroid gland would do if it were healthy.
Unfortunately, we don’t have good data to give us this information so we need to rely on patient experience for now.
Based on my experience, I’ve found that most thyroid patients experience a therapeutic benefit when taking somewhere around 100 to 200 mcg per day.
There are definitely some thyroid patients who are just really sensitive to thyroid hormones and can probably get by with T2 dosing less than 25 mcg/day, but most people will need more.
And, right now, I would recommend staying away from dosing in the 300 mcg/day range just because that’s too close to the safety cutoff.
Who Should Use T2?
So should you give T2 a try?
That’s the question that thyroid patients ask me all of the time and here’s my response:
It depends on how you are feeling and what you are trying to achieve!
If you are someone who is feeling lousy right now and still experiencing thyroid symptoms despite taking thyroid medication, then, yeah, taking T2 is probably a good idea.
Taking T2 in this setting will likely make your thyroid medication more effective and help you better manage your symptoms.
This, I think, is the best use case for taking T2.
To round out a thyroid medication regimen and more closely match the thyroid hormone production that the healthy gland would provide if it were working.
Another reason to use T2 is if you are a thyroid patient struggling to lose weight.
Given T2’s impact on metabolism, cellular ATP production, muscle health, and heat production, it makes a lot of sense to use it in this setting as well.
T2 isn’t a magical weight loss pill, but it can enhance your metabolism and make your weight loss efforts (like diet and exercise) much more effective.
If you are interested in learning more about how T2 can help you lose weight, then I’d recommend checking out this article next.
And by the way, if you want to get my recommended T2 supplements, you can see the capsule form I recommend here and the cream form that I recommend here.
Now I want to hear from you:
Is this the first time you have heard about T2?
Have you heard about it but been scared to try it due to the side effects?
Are you thinking about giving it a try? Why or why not?
Scientific References
#1. ncbi.nlm.nih.gov/books/NBK537039/#:~:text=The thyroid gland is responsible,as the liver and kidneys.
#2. ncbi.nlm.nih.gov/pmc/articles/PMC9646642/
#3. ncbi.nlm.nih.gov/pmc/articles/PMC4272399/
#4. pubmed.ncbi.nlm.nih.gov/26593437/
#5. ncbi.nlm.nih.gov/pmc/articles/PMC3241518/
#6. ncbi.nlm.nih.gov/pmc/articles/PMC4272398/
First time I’ve heard of it, and yes I want to try it. Even though my doctor told me a week ago to restart mounjaro(its in my fridge)I’m dragging my feet
Hi Marnie,
There are plenty of additional options for weight loss both from a medication perspective as well as from a lifestyle perspective.
You can find additional information here:
https://www.restartmed.com/prescription-weight-loss-medications/
https://www.restartmed.com/perfect-thyroid-diet/
I have ordered your T2 on Amazon and wait its arrival. I am transitioning to carnivore diet, and am finding it very difficult. I believe my thyroid and adrenals are shot. It seems my body is certainly fighting the fat adaptation.
Hi William,
Most thyroid patients will find that they feel better with more carbohydrates than what is allowed on keto/carnivore diets. You can learn more about that here: https://www.restartmed.com/how-many-carbs-should-you-eat-with-hypothyroidism/
I ordered T2, T3 Conversion Booster and Thyro ADK. Within 5 days of taking T2, I felt great! I had more energy , no brain fog and elevated sense of well being. By the end of the week, I had intense heart palpatations at night. I have since stopped T2, and do not know where to go from there.
My regular dose of NT thyroid hormone is 6 grains 3, 120 mg. I was treated for thyroid cancer over30 years ago. I do take Tegretol and wonder if that has any impact. Any insight would be appreciated. Thank you !
Hi Dianna,
At the doses I recommend, T2 will not cause heart palpitations. It is possible, however, that the supplements you are taking have enhanced thyroid function to the point that your thyroid medication needs to be adjusted (reduced). In this scenario, it’s not the supplements causing the heart palpitations, it’s the medications because your own body is now able to produce more thyroid hormone on its own.
I have read about T2 and am seeing that T2 can accumulate in the liver for some people. Do you have anyone in your study that had this happen?
Hi Edie,
Can you share the study you are referring to regarding the pooling of T2 in the liver? I’ve read a lot of papers about T2 and I’ve never seen one to suggest that this can happen.
In regards to our database of people using T2 (which is now well over 10,000 people), we haven’t seen any people experience liver issues while taking it.
I’ve read about this online too from a Dr. Christianson and he cited one of the studies below (the other was linked within when it referred T2 accumulating in the liver).
As someone who has recently begun using the T2 cream, I’d love you perspective on their findings. The most concerning points they posit are: (1) T2 enlarges the heart, (2) T2 suppresses the HPT axis and thus thyroid levels even at lower tested dose, and (3) T2 accumulates in the liver.
It was a rat study, so I’m unsure how applicable it is to humans, and I’m also unsure how the two different studied doses compare to what’s in the Essential T2 supplement and new T2 cream, which could be important.
Can you share your perspective on these studies and their assertations?
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4272398/#B11
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4272399/
Hi Timothy,
I’ll address this in more detail either as an update to this article or as a standalone article, but I have no concerns about any of the points that you raised. Here’s my justification for that stance:
1) T2 enlargement of the heart.
The study you cited does show that T2 has the capacity to result in cardiac enlargement, but only when preposterously high doses are used. But this isn’t unique to T2, as all thyroid hormones, including T3 and T4, can do the same, provided you use high doses.
Here’s a quote from the article you cited:
“The higher dose of T2 used was 80 times that of T3. Thus, it allows for its estimated lower affinity for the TH receptors, assuming that the affinity of T3 for the receptors is indeed 100 times that of T2 (8). This high dose of T2 essentially mimicked all the physiological effects obtained with the T3 dose. These effects included suppression of the HPT axis, decreases in fat mass, serum leptin, and cholesterol, and increases in lean mass, food intake, and hepatic expression of TH-dependent genes relevant to lipid metabolism (see summary of results in Table 1).”
What the researchers did was give the rats an insanely high dose of T3, enough to cause TSH suppression and cardiac enlargement, and then multiplied that dose by 80 (to obtain their T2 dose) and then gave that dose to the rats and observed their reaction.
They found that the dose of T2 that was 80x that of T3 had the same impact on the heart and HPT axis as the incredibly high T3 dose.
The takeaway from this is “So?”.
Of course, you’d expect that such a high dose of T2 and T3 would have comparable effects, but humans are never given supraphysiologic doses of T3 in the real world by most physicians, nor are they taking such high doses of T2. So all this study proves is that insanely high doses of T2 are just as bad for the body as insanely high doses of T3.
But we don’t care about insanely high doses, what we care about are physiologic doses and their impact on the body.
And the human studies that I’ve seen show that doses of T2 less than 300 mcg per day have NO impact on the HPT axis nor on cardiac size.
It seems like those who are trying to use this study as a reason to avoid T2 are making the assumption that just because an incredibly high dose of T2 causes problems, any dose of T2 will cause problems, but this assertion is proven false by many studies.
There is a physiologic level of T2 that the body can tolerate and, when you exceed that value, you would expect problems to arise. But, again, this applies to all thyroid hormones including T4 and T3. You can induce a hyperthyroid response (cardiac enlargement and HPT suppression) with any thyroid hormone, provided you take more than you need.
2) T2 suppresses the HPT axis and thyroid hormone levels at lower doses.
Here’s a study in humans showing that a dose of 300 mcg per day had no impact on TSH, FT3, or FT4: https://pubmed.ncbi.nlm.nih.gov/22217997/
The best argument I’ve seen here is that researchers will agree that low doses are not harmful, but they have no positive effect on body composition or on cholesterol, but this has been proven wrong in the real world. We have a database of well over 15,000 thyroid patients who have used T2, at doses under 300 mcg per day, and we do not see HPT suppression or cardiac complications, but we do see positive impacts on energy, cholesterol, weight, and other indirect markers of thyroid function.
So the argument that low doses are safe but ineffective doesn’t seem to extend to humans, even if that is seen in some studies of rats (though I stil debate this assertion).
3) T2 accumulates in the liver.
I’ve since seen this study, but it’s another “so?” type of thing. The researchers in the article you mentioned suggest that the reason T2 has a positive impact on cholesterol is because it concentrates in the liver:
“Our experiment for the first time revealed elevated serum 3,5-T2 concentration and unexpectedly high 3,5-T2 liver content after 3,5-T2 injections. The latter observation indicates 1) significant hepatic 3,5-T2 uptake by still unidentified transporter(s) followed by intrahepatic accumulation of 3,5-T2, and 2) inefficient elimination of 3,5-T2 from liver. This constellation resembles features of the high uptake and accumulation of the TRβ-selective ligand eprotirome, which exhibited remarkable hepatic tissue selectivity and strong antihyperlipidemic effects in human volunteers (11, 12)”.
I haven’t seen any research to suggest that T2 causes hepatoxocity, so this accumulation in the liver is likely a good thing and appears to be at least partially responsible for why we see beneficial effects in people who use T2 for fatty liver.
Hi, I ordered the T2 about 3 weeks ago. I’m on Tirosint 88 and cytomel 10mcg daily. Since switching from armour 3 years ago I’ve gained 30lbs and can’t seem to stop the weight. I work out almost 2 hours a day, still nothing so I thought maybe T2 would help. The first week, it felt way too strong so I dropped it to half, then the next week I increased it a bit. By the end of the 3rd week, my heart was going crazy. I couldn’t slow it down. This past Monday it raced so badly I ended up passing out and in the ER. All the test came back clean. Cardiologist gave me an ear full for trying T2 and wants me to stop T3 for a month. My labs look worse than ever. T3 dropped to 2.8 since starting the T2. Now 3 days later I can’t even get up without my heart going crazy. How is this even possible. Everywhere I read it said T2 was safe….
Hi! I had my thyroid removed Feb 1st due to Hashimoto’s thyroiditis (I swung hyper and gained over 100 lbs over 2yrs) is this ok to use with levothyroxine? I’ve asked to be put on T3 but my Endo won’t budge. I’ve only lost 20lbs since my surgery and I’ve been stuck for a month. I was a runner before the high heart rate sidelined me so I’m walking 3 times a week at a brisk pace with a 1200 calorie clean diet. I’m also 51 and in menopause. With my thyroid being gone it’s like I have a new body I don’t understand at all. Please help!
Hi Wendy,
Yes, T2 can be used with all thyroid hormones and medications including levothyroxine.
I have a 68 y/o patient , had thyroid CA 2000 , thyroidectomy.Has been on synthroid 200mcg . She developed euthyroid sick syndrome . She gained 30 lbs fatigue , brittle nails , lair loss. The orthopedic surgeon wants her to lose weight to improve an intraoperative femoral nerve injury . Had BW :TSH 0.01, T41.26, reverseT36.3 ,thyroglobulin AB <0.9 . Sent her to endocrinologist who decreased synthroid to 175 mcg . She is very unhappy as is ortho. She continues to gain weight .
Hi Jeanne,
She sounds like a great candidate for T3. If you reduce her dose of T4 and sub it out for T3, you’ll likely see a big improvement in her labs and symptoms. Her endo won’t like it, that’s for sure, but she will.
Every single patient is different in regards to their T3 sensitivity, so your mileage may vary, but most can handle a ratio of 80:20 (T4:T3) without issues. Those with ESS may temporarily need more T3 than 20%, but, again, it’s highly variable.
I wouldn’t move her to that dosing schedule too quickly, but you could probably get there using 5 mcg increments of T3 over the course of 8-12 weeks with a goal.
As a general guideline, aim for around these levels:
– 100 mcg (as Tirosint or tirosint sol)
– 20 mcg of T3 (as liothyronine or cytomel)
– 100 mcg of T2 (as 3,5 diiodo-l-thyronine)
Adjust based on symptoms, resting heart rate, and lab tests.
hi
i am 84 years old and my thyroid is lazy i gained weight on my stomach and my arms and hips i take black seed oil by Havasu company bought from amazon one pill in the day and one pill at night i eat only one meal in the afternoon and i am not feeling hungry i walk to work four days a
week and exercise on a stationery bike and do a little bit exercise i have lost on my buttocks and my thighs and the flab on my stomach but the weight remains the same i have arrythemia of the heart and i have been taking these pills for the last forty years and the dr does not want to change it 1. DIL TIAZEM MCL 240 MG ONE Tablet at night and the 2nd one is LOSARTHAN POT 100MG ONE TABLET AT NIGHT CAN I TAKE CAN I TAKE T2FOR MY THYROID WHAT YOU RECOMMEND OR IS THIS GOING TO DISTURB MY HEART PALPATATIONS I HAD BURSITIS AND SCIATICA ON MY LEFT LEG AND HAVE ARTHRITIS ON MY RIGHT KNEE AND THE LOWER PART OF BACK ARTHRITIS AND FIND IT DIFFICULT TO WALK BUT I STILL WALK, CAN YOU GIVE ME YOUR GOOD ADVICE I WANT TO LOSE THE WEIGHT PLEASE EMAIL ME AND I WOULD REALLY APPRECIATE AND ALSO EAT AN APPLE.AND CARBS PLEASE HELP ME THANKS LUIZINHA FERNANDES
68 yoa post meno, started on T2 and within 2 weeks started having the same symptoms that i used to get prior to menstrual periods… lower back pain and tender swollen breast. Is this a normal symptom on T2? I still have all my “female” parts, but am certainly not interested in them restarting (haha), so should i continue use?
Hi CathyR,
T2 really shouldn’t have any impact on estrogen levels so I would be hesitant to blame your symptoms on that. Have you started any other medications or hormone creams (like progesterone cream) around the same time?
Dr Childs, i have been on oral progesterone for over a decade now, but have recently added your T3 Conversion supplement hoping to up my T3 levels which are right at midlevel. I am no longer on Armour now that my thyroid numbers are within level. However, I need to lose weight, and I’ve read your blog about T3 needing to be upper range to effectively do that, hence my adding the Conversion supplement, praying it helps. Thanks for your content about the estrogen, i appreciate it.
Hi CathyR,
That’s a good strategy, but you’ll also want to combine that with diet and exercise. There are several ways you can increase T3 outside of the use of supplements: https://www.restartmed.com/increase-free-t3-naturally/
Well I bought your T2 lotion based on an article you wrote promoting it. It seemed to me that any “anyone” could use it, but now I’m not so sure based on your later articles. Only used a little once or twice so far.
I have Hashimoto’s and still in “normal” range ( obviously not optimal range). The “gray area” as my Endo calls it and he leaves it up to me whether or not to take meds, which I don’t. Don’t like meds in general. On an AI which exacerbate many of my thyroid symptoms.
Is it mainly for people already on T4 and or T3?
,
Hi Dorthe,
T2 can certainly be used in your condition and by pretty much anyone with a known or suspected thyroid problem (even in people without thyroid problems who are just trying to optimize weight/cholesterol/etc.). It’s not just for people taking T4 and T3, though it is also beneficial for them as well.
What part of this article led you to believe that it’s only helpful for those taking thyroid medication?
Hi, I would like to ask if any of you have used T2 3.5 diiodo-l-thyronine to treat covid-19. I took it when I couldn’t breathe anymore and in 4 days I was completely cured. Thanks
Hi Remigio,
I personally haven’t seen it used in that situation, but I will let others reply if they have.