Tirosint vs Levothyroxine: The Case for Switching Thyroid Medication

Tirosint vs Levothyroxine: The Case for Switching Thyroid Medication

You've probably heard from other patients that switching from Levothyroxine to Tirosint made all the difference. 

Considering that they are both T4 only thyroid medication, what is the difference between these medications?

Why do some patients have decreased symptoms, lose more weight and feel better on Tirosint but not on Levothyroxine?

Is there a difference between this thyroid medication compared to the others?

It turns out that many patients actually do much better on Tirosint (but not everyone). ​

In this article I am going to discuss who might do better on Tirosint, why most thyroid patients will probably do better on this medication and make a case for switching thyroid medications...


Tirosint the T4 only Thyroid Medication

​As mentioned previously Tirosint is a T4 only thyroid medication

That means that it contains only the T4 thyroid hormone.

Other T4 only thyroid hormone medications include: Synthroid, Levothyroxine and Levoxyl.

​If you've read my blog before you probably know that I've spent a lot of time and energy writing about how T4 only thyroid medications generally don't work well for many patients. 

Why is that?

Tirosint ingredient list

Well T4 thyroid hormone is not an active thyroid hormone.

The only active thyroid hormone is T3.

And in order to create T3 your body must use T4 as a substrate and precursor hormone.

So many providers give patients T4 thyroid hormone hoping that ​the body will naturally convert this T4 into the free T3. 

The problem is that under special circumstances the body will actually produce reverse T3 (the anti thyroid metabolite) instead of T3 making the problem worse.

This is the primary reason that many thyroid patients simply don't do well on T4 only thyroid medications.

But this isn't the whole story.

It turns out that many patients would probably do well on T4 thyroid medication IF (and this is a big if), it was being absorbed properly AND if they don't have any negative reactions to the fillers/inactive ingredients in the thyroid medication.

You see:

​All T4 thyroid hormone medications contain the active ingredient T4, what they differ in is the inactive ingredients. 

And many people are sensitive to these inactive ingredients. 

It's these inactive ingredients that change the absorption of the hormone or simply cause reactions themselves. 

This reaction can trick patients into wrongly believing that their medication doesn't work or that that hypothyroidism isn't the cause of their symptoms. 

​But what if you could take a thyroid hormone medication with very few inactive ingredients that would almost ensure proper absorption and assimilation?

This would remove the conversion variable and give you clear insight as to whether or not T4 only thyroid medication works for you. ​

Well that's exactly how Tirosint works. 

Tirosint contains the least inactive ingredients out of all of T4 only thyroid medications ​and many patients have reported an improvement in overall symptoms when switching. 

Why do you think these patients notice improvement when switching?

Is this medication magically better than Levothyroxine or Synthroid?

No, it's a matter of absorption and in the GI tract of the thyroid hormone and a reduced risk of negative reactions to the fillers.

And much of this change has to do with the ingredient list (including both active and inactive). 

Tirosint vs Levothyroxine vs Synthroid

To illustrate this point let's go over the ingredient list of these medications quickly.

Ingredient list of Tirosint (both inactive and active ingredients): ​

  • Levothyroxine (this is the T4 thyroid hormone) <--- Active ingredient
  • Gelatin <--- Inactive ingredient
  • Glycerin <--- Inactive ingredients
  • Water <--- Inactive ingredient

​As you can see Tirosint has 1 active ingredient and 3 inactive ingrediets for a total of 4 ingredients total. 

Compare this to Levothyroxine:

  • Levothyroxine (this is the T4 thyroid hormone)
  • Butylated hydroxyanisole
  • Silicon dioxide
  • Crospovidone
  • Magnesium stearate
  • Mannitol
  • Cellulose
  • Povidones
  • Sodium lauryl sulfate
  • Sucrose
  • And color additivies include dyes (more below and depending on the strenght)

As you can see Levothyroxine has a huge list of inactive ingredients. 

It is these inactive ingredients that alter absorption and therefore influence the amount of thyroid hormone that makes it into your body.

​These inactive ingredients can also cause a list of reactions including: dizziness, headaches, reflux, flushing, hives/rashes, etc. 

These variables make it difficult to determine ​if any negative symptoms you may experience on a thyroid medication are due to the hormone or due to the inactive ingredients. 

Special note:

​Below is the list of fillers, dyes and additives to each dose of Levothyroxine. 

You can see that the 50mcg dosage does not have any extra dyes, so if you can't switch medications from say Levothyroxine to Tirosint, it would be worth a trial of switching to a 50mcg dose.

In fact, when I dose levothyroxine I almost exlusively use the 50mcg dose because of this.

If you are on 125mcg of Levothyroxine then using 2.5 tablets of 50mcg may improve your symptoms vs using the 125mcg tablet. ​

levothyroxine added dyes and fillers

​Who should consider using Tirosint?

​Does this mean that every patient on Levothyroxine who is still feeling symptomatic should switch to Tirosint?

No (nothing is ever that easy!), but there are a few patients who should strongly consider making the switch to Tirosint if they are on Levothyroxine or Synthroid.

​If you fall into any of the following categories then Tirosint may be a better option for you than Levothyroxine/Synthroid and/or Levoxyl: 

  • Patients with gastrointestinal issues including (but not limited to): Low stomach acid, acid reflux, SIBO/SIFO, IBS, IBD, and any GI related surgery (including gastric bypass)
  • Patients who don't tolerate Synthroid, Levothyroxine or Levoxyl, or who have experienced any of the likely negative reactions to inactive ingrediets
  • Patients with multiple food allergies or sensitivities to multiple foods
  • Patients with increased intestinal permeability
  • Patients who don't tolerate NDT medications or are too sensitive to T3 containing medications
  • Patients who are extremely sensitive to medications and supplements or who react to these substances at very low doses
  • Patients who have experienced some improvement of Levothyroxine or Synthroid but still have room for improvement

​This list should serve as general and broad guidelines for who should consider switching to Tirosint. 

One important point I want to expand on is the implication that gastrointestinal problems have on thyroid hormone (and other nutrients).

Hypothyroid patients (yes even those already on thyroid medications but still with symptoms) are in a tricky situation.

Thyroid hormone is required for proper stomach acid (HCL) production and HCL is required for proper thyroid (and other nutrients) hormone absorption.

This means that if you are being under treated then there is a chance that you are also not fully absorbing thyroid hormone and/or other nutrients - making your problem worse.

This general lack of stomach acid can also worsen or create other intestinal problems which make absorption even worse.

This may explain why some studies show that up to 50% of hypothyroid patients have SIBO, or why up to 40% of hypothyroid patients have vitamin B12 deficiency.

​The point is that these GI problems are very important and contribute to a reduction in absorption of not only oral thyroid hormone medications but also nutrients which can worsen symptoms. 

It's worth taking some time to point out that replacing thyroid hormone doesn't necessarily reverse these conditions and taking extra steps to treat these GI problems if present will be necessary in many patients. ​

​Does Tirosint cause more weight loss than Levothyroxine or Synthroid?

​I get this question from many patients in some form and the answer is that yes, it might cause weight loss in some individuals. 

This is only true if your body has no issues with the conversion process of T4 to T3 and if your problem with levothyroxine was a lack of absorption.

If the change from Levothyroxine to Tirosint results in an overall increase in thyroid hormone in the body, and the conversion of T4 to T3, then yes, Tirosint may result in weight loss.

This makes the huge assumption that your body has no issues with converting T4 to T3 and this is a very big assumption to make. 

We've spent time focusing on the absorption issue, but in reality this general lack of absorption and reaction to inactive ingredients probably represents 20-30% of patients. 

Another 30-40% of patients simply need T3 added to their T4 dose for optimal results, and altering T4 dosing won't necessarily change this. ​

You can read more about why Levothyroxine can actually contribute to weight gain here, and you can read more about how to use Synthroid and Levothyroxine for weight loss properly here.

Combining Thyroid Medications (T4 + T3)

This is probably the best way to use Tirosint and this is how I use it effectively in my practice. 

Switching from Tirosint to Levothyroxine ​

Tirosint by itself usually results in a reduction of overall hypothyroid symptoms due to superior absorption, but this effect is multiplied with the addition of T3 containing thyroid medications like Cytomel or Liothyronine.

Other thyroid hormones and medications can safely be added to Tirosint, but remember that general rules for taking thyroid hormone sill apply to help improve absorption. 

​One of the best parts about switching to Tirosint is that most providers won't argue with you about the change. 

Tirosint is still a T4 only thyroid medication and using this medication fits into the current paradigm of thyroid treatment (however flawed this paradigm might be).

Compare that to trying to get your provider to switch you to NDT, which is infinitely more difficult. ​

Nowadays it's also becoming more common place for providers to add lower dosages of T3 to T4 thyroid doses.

So switching from say 125mcg of Levothyroxine to 100mcg of Tirosint + 5-10mcg of Cytomel is becoming more commonplace, than say switching from 125mcg of T4 to 2-3 grains of NDT. ​

​Tirosint Dosage vs Levothyroxine Dosage

Is there a difference in dosages between these two medications?

While both contain equivalent dosages and concentrations of thyroid hormone, some patients do find that switching over may result in almost hyperthyroid like symptoms.

In my opinion this results from increased absorption and a flush of thyroid hormone into the body.

If this does occur in you, simply slightly reducing the dose is usually enough to control these symptoms.

But in general the dosage between these thyroid hormone medications is equivalent. ​

FAQ + Recap

The bottom line is that many patients stand to benefit from switching to Tirosint from Levothyroxine or Synthroid (and even other forms of thyroid medications). 

This improvement is felt to be due to increased and superior absorption in addition to a reduction in symptoms related to inactive ingredients.

Remember that Tirosint has 1 active ingredient and 3 inactive ingredients making it the "cleanest" thyroid hormone medication.

Special interest should be taken in certain patients with gastrointestinal symptoms as these patients tend to have low stomach acid and other nutrient deficiencies.

Another huge benefit of Tirosint is that this medication fits the current thyroid treatment paradigm and because of this many providers are more willing to prescribe this medication over other formulations.

At the end of the day you are a unique patient and it may take a combination of time and trial and error to find your optimal dose, but don't give up! With persistence you will get there. 

​Below I've also included some frequently asked questions that I receive from patients regarding Tirosint, if your questions weren't answered above they should be answered below. 

If you have any other questions or comments please leave them in the comment section below as I check these frequently. 

Is Tirosint a T4 only thyroid medication?

​Yes, Tirosint is a T4 only thyroid medication. 

It does NOT contain T3.

Medications that are T4 only thyroid medication include: Levothyroxine, Synthroid, Tirosint and Levoxyl.

Medications that contain T3 only include: Cytomel, Liothyronine and SR T3.

Medications that contain both T4 and T3 include: Armour thyroid, WP thyroid and naturethroid.​

Will it work for for me?

There is no way to know for sure if Tirosint will work for you.

In my experience I've found that most people do subjectively experience a reduction in hypothyroid symptoms when switching to Tirosint.

This is also seen outside of my clinic and in many patients on other blogs and forums.

​When trying to optimize and reduce your symptoms it's important to take into account other factors like T4 to T3 conversion, inflammation and other hormone imbalances. 

Can Tirosint cause weight gain?

Like other T4 only thyroid medications Tirosint can indirectly lead to weight gain.

This usually occurs from improper thyroid conversion and the production of too much reverse T3.

Recall that reverse T3 is the anti thyroid metabolite and directly competes for binding and cellular activation with T3.

The more reverse T3 you have in your body the more likely you are to experience hypothyroid like symptoms (even with a normal or low TSH).

Many patients on T4 only thyroid medications also may experience a condition known as Low T3 syndrome which is felt to be due to a variety of reasons including lack of thyroid conversion (though this condition doesn't always have high levels of reverse T3). ​

How do you take it?

Like other Thyroid hormone medications Tirosint should be taken on an empty stomach in the early morning. You should also avoid supplements and the intake of food for at least 60 minutes after taking it.

​Some patients opt to split the dose and/or take this medication at night, but these are advanced techniques and depend on symptoms. 

Can it be used with other Thyroid Medications?

Yes, Tirosint can safely be combined with other thyroid hormone medications.

​It is often best used in combination with Cytomel or Liothyronine. 

Does Tirosint have any Side Effects?

Like other thyroid hormone medications Tirosint (if used in high doses) can result in hyperthyroid like symptoms:

  • Heart palpitations
  • Feeling of anxiety or jittery sensation
  • Rapid weight loss
  • Sensation of overheating or feeling too warm
  • Anxiety, depression or other mood changes
  • Insomnia or change in sleeping patterns

These would be considered adverse or serious side effects and if you experience any of these you should seek medical care as soon as possible. 

​Because of the small list of inactive ingredients many patients tolerate Tirosint quite well and generally don't complain of minor side effects like headaches, rashes, flushing, etc. 

These minor symptoms are usually self limiting and tend to resolve within 1-2 weeks. ​

How much does Tirosint Cost?

Because Tirosint is a newer formulation of T4 thyroid medication the price tends to be more expensive than other generic brands. 

You can see a list of cash prices below using goodrx.com:

Without insurance, and for the 100mcg dose, Tirosint will cost around $122 (depending on your location). ​

Tirosint cash price

You can use goodrx to get a discount on medications (even other formulations of thyroid hormone and other medications). 

Tirosint does have coupon codes as well which can help reduce the cost down to $35 per month. ​

Tirosint savings card

You can find more information about the coupons here

At the end of the day, paying up to $100 per month may be expensive but if it improves your quality life the price may be more than worth it. 

Now it's your turn:

Are you on Tirosint? Is it working for you?

Have you been able to lose weight when switching medications?

Why or why not?

Leave your comments below! ​

Westin Childs

Dr. Westin Childs is a Doctor of Osteopathic Medicine. He provides well-researched actionable information about hormone-related disorders and formulates supplements to treat these disorders. He is trained in Internal Medicine, Functional Medicine and Integrative Medicine. His focus is on managing thyroid disorders, weight loss resistance, and other sex hormone imbalances. You can read more about his own personal journey here.

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