Follow on

Ingredients Binders and Fillers in Thyroid Medication-Is Your Thyroid Medication Making You Sick?

Today, I wanted to share with you some information about ingredients, binders, and fillers within your thyroid medication that you should be aware of. Why is this important? Studies over the last few years are very clear that thyroid disease can be aggravated by some of the ingredients found within the very medication you just took this morning. Not only has gluten come under the gun, but so has corn, dairy, soy, and some of the other colors and additives we often find in thyroid medication.

Is Your Thyroid Medication Making You Sick?

Since many of the patients I work with around the world are taking thyroid hormones, I thought reviewing some of the ingredients, binders, and fillers would be a good topic to discuss a little further so that you can have this discussion with your prescribing doctor.

The ultimate goal in my office is always first and foremost to restore a person’s thyroid health so that they don’t need to take thyroid hormones. This is not always the case.  So, if this is you, I want you to be aware of these ingredients and how they may be potentially causing you harm.

Synthetic Thyroid Hormone. There are numerous brands of synthetic thyroid hormone, but I’m going to focus on a few of the more common brands.


Synthroid is synthetic T4, and if you visit, it currently states that ” Synthetic T4 is identical to that produced in the human thyroid gland (1).

But right below this, the inactive ingredients are listed, which include acacia, confectioner’s sugar (contains corn starch), lactose monohydrate, magnesium stearate, povidone, and talc. And then below this, you’ll see some of the ingredients, binders, and fillers which include color additives, FD&C Yellow No. 6 (in 25 mcg tablets), FD&C Red No. 40, and FD&C Blue No. 2 (in 75 mcg strength), etc.

So when you factor in the inactive ingredients it becomes quite obvious that taking synthetic T4 isn’t exactly “identical” to thyroid hormone which is produced by the thyroid gland. And while it’s true that many people seem to do fine when taking synthetic thyroid hormones and don’t react to these binders and fillers, others don’t do fine.

When someone experiences an increase in symptoms upon taking thyroid hormone, sometimes this is due to the “inactive ingredients.” For example, if someone is sensitive to corn, then they often react to synthetic thyroid hormone. This is especially the case if someone has celiac disease. Gluten can cross-react with Corn and many other grains.

Gluten Cross Reactivity

Gluten cross-reactivity is a term used to describe a phenomenon where the immune system mistakenly identifies proteins in foods other than gluten as similar to gluten and launches an immune response against them. This immune response can occur in individuals with celiac disease or gluten sensitivity, leading to symptoms similar to those triggered by gluten consumption.

In celiac disease, a genetically predisposed autoimmune condition triggered by the ingestion of gluten, the immune system reacts to gluten proteins found in wheat, barley, and rye. However, some individuals with celiac disease or non-celiac gluten sensitivity may also experience symptoms when consuming foods that contain proteins with a similar structure to gluten. This molecular mimicry can lead to cross-reactivity, where the immune system responds to these gluten-like proteins as if they were gluten.

Common sources of cross-reactive proteins that may trigger immune responses in individuals with gluten sensitivity include:

1. Dairy Proteins: Proteins found in dairy products, particularly casein and whey, can cross-react with gluten proteins and elicit immune responses in sensitive individuals.

3. Quinoa: Despite being a gluten-free grain, quinoa contains proteins that can mimic gluten, leading to cross-reactivity in some cases.

4. Rice: Some individuals with gluten sensitivity may experience cross-reactivity to certain proteins in rice, causing adverse immune reactions.

5.  Corn: Proteins in corn may exhibit structural similarities to gluten proteins, triggering cross-reactivity in susceptible individuals.

It is essential to note that not all individuals with gluten sensitivity will experience cross-reactivity to these foods, and the extent of cross-reactivity can vary from person to person. The diagnosis of gluten sensitivity and the identification of potential cross-reactive foods often involve a combination of medical evaluation, laboratory testing, and dietary interventions.

I have done several videos on this very topic and you can learn more about Gluten-Cross reactivity below.


Are You Reacting to Your Thyroid Medication?



Levoxyl is another brand of synthetic T4. The ingredients include Microcrystalline cellulose, croscarmellose sodium, magnesium stearate, calcium sulfate dihydrate and sodium bicarbonate, along with color additives depending on the tablet’s strength (2).


Levothyroid is another brand of synthetic T4. The ingredients, binders, and fillers include Microcrystalline cellulose, calcium phosphate dibasic, povidone and magnesium stearate, along with color additives depending on the tablet’s strength (3).


Cytomel (liothyronine sodium) is a brand of synthetic T3. Some of the ingredients, binders, and fillers consist of calcium sulfate, gelatin, starch, stearic acid, sucrose, and talc (4).


This is a form of natural thyroid hormone that is derived from porcine thyroid glands. It consists of both T3 and T4, and many people do better when taking natural thyroid hormone when compared to synthetic thyroid hormone. However, some people react to the binders and fillers in Armour. The inactive ingredients include calcium stearate, dextrose, microcrystalline cellulose, sodium starch glycolate and Opadry white (5).


This is another form of natural thyroid hormone that is derived from porcine thyroid glands, and therefore also consists of both T3 and T4. The binders and fillers in Nature-Throid include colloidal silicon dioxide, dicalcium phosphate, lactose monohydrate, magnesium stearate, microcrystalline cellulose, croscarmellose sodium, stearic acid, and Opadry II (6).

Is There Gluten In Your Thyroid Hormone Medication?

Many people with Hashimoto’s Thyroiditis attempt to avoid gluten and with good reason. However, most people don’t consider that their source of thyroid hormone medication might include gluten. Although both Armour and Nature-Throid are gluten-free, there are still binders and ingredients that may pose problems. Not all forms of levothyroxine are gluten-free and if you suspect that your thyroid medication is causing a problem, it may be wise to check for gluten sensitivity, celiac disease, or Gluten-Cross reactivity.

According to the website, the only two brands of levothyroxine that are guaranteed to be gluten-free include Lannett and Mova. The manufacturers of Synthroid can’t guarantee that this is gluten-free. Both Levothroid and Levoxyl are gluten-free. Cytomel is also gluten-free, but gluten may not be the only ingredient you may be reacting to.

10 Steps To Supporting Your Thyroid Naturally

Learn more about 10 steps to supporting your Thyroid Naturally

Some Additional Articles We Recommend Reading

  1. Thyroid and Blood Sugar Connection. Everything You Need To Know About Blood Sugar and Thyroid Disease
  2. Ingredients Binders and Fillers in Thyroid Medication
  3. Low T3 Explained. What You Should Know About this Thyroid Hormone
  4. Adrenal Fatigue and Thyroid: How Are They Connected?
  5. The Stress Hormone Cortisol and Blood Sugar
  6. Iron Deficiency and Hypothyroidism- How Iron Anemia Shuts Down The Thyroid
  7. Why Some Women feel Worse When They Take Thyroid medication.
  8. 10 Steps to Supporting Your Thyroid Naturally
  9. Gluten Sensitivity And Yeast Cross Reactivity- Why Yeast Causes Problems
  10. Gluten and Milk Products- Cross-Reactivity and Why You Should Avoid
  11. Gluten -Corn Cross Reactivity- Why Going Gluten-Free Doesn’t Always Cut It.
See Other Recent Post!

Creating health doesn't have to be a guessing game!

Our Team will help you harness your health so you can trust your body and feel like YOU again. We can help find your Root Cause.