What You Must Know About Your Thyroid Medicine: Falsehoods, Formulations, and Fillers

What You Must Know About Your Thyroid Medicine:  Falsehoods, Formulations, and Fillers

Are you taking thyroid medicine but still feeling sick?

This doctor graduated top of her class in medical school and has received multiple prestigious grants from the American Thyroid Association. Her pearls of wisdom are must-read for every hypothyroidism patient.

Written by Brittany Henderson, MD, ECNU & Allison Futterman

Okay, so you’ve been diagnosed with hypothyroidism, and are looking at a lifetime of thyroid hormone supplementation. But where do you start? Do you just go with the first thyroid medicine prescribed by your doctor? Do you research extensively online and pick one that “sounds best”?

Finding the right medication(s) to treat your hypothyroidism can be a frustrating experience. Like just about everything else having to do with healthcare, there isn’t a “one-size-fits-all” approach when it comes to thyroid medication. Let’s start by dispelling some common myths or falsehoods.


Thyroid Falsehood #1

“Natural” thyroid supplementation is best!

OK, OK, we admit it! Some people do absolutely excellent on natural desiccated thyroid (also called NDT). NDT is essentially pig thyroid gland packaged in pill form. Examples of NDT include Nature-throid, Armour, and NP thyroid. Those who do well with NDT report improvement in energy level, wellbeing, weight loss, and mood. For some, NDT is truly a Godsend.

For others, though, NDT can be associated with worsened anxiety, shortness of breath, chest pain, and exacerbation of other medical illness. In fact, some patients wind up in the emergency room or hospital due to side effects. This group is sensitive to NDT and doesn’t do as well.

Thyroid research hasn’t come far enough to determine who will and who won’t do better with NDT. Currently, there is a trial-and-error process to uncover one’s tolerability to natural thyroid supplementation. We hope thyroid research will catch up in the future.

For now, just know that NDT is good for some—but not for others.

Thyroid Falsehood #2

T4-only medicines (Synthroid orLevothyroxine) should be standard of care.

Just like the falsehood that says NDT is best for everyone, we have to stop believing that T4-only formulations should be our standard approach to thyroid replacement.

Some people don’t absorb and metabolize T4-only forms of thyroid medicine. These people have additional medical conditions, genetic differences, or are on medications that dramatically affect how they process T4. In fact, many of these patients don’t do well with T4 to T3 conversion and end up feeling sluggish, gaining weight, and struggling to reclaim their pre-thyroid illness life.

Many others do just great with T4 only medications. Their bodies take T4 and readily convert it to T3, just like they did prior to having thyroid disease. In fact, 80% of the thyroid hormone normally produced by the thyroid gland is T4. This T4, or inactive thyroid hormone, is converted (and sometimes not readily converted) to T3 at the body’s discretion to allow for optimal thyroid function. For example, after a marathon race, the body intentionally down regulates production of T3, or active thyroid hormone, to allow the muscle tissue time to regenerate.

Knowing which patients do well and which patients don’t do well on T4-only medicine options is the mark of a skilled thyroid clinician.

Thyroid Falsehood #3

There is a one-size-fits-all approach to thyroid replacement.

This is the biggest myth of all! Thyroid replacement methods should not take an either/or approach. There is a binary approach to medication in the thyroid community today. One side of the aisle prescribes T4-only, for everyone. The other side of the aisle prescribes NDT only, for everyone. What’s needed is for medical providers to be less obstinate and more open minded, allowing them to see patients as they really are—individuals who absorb, process, and tolerate thyroid medications differently.

Because, despite the message we’ve been implicitly given, we’re not all the same!

So how do we as a thyroid community start changing our mindset? And how do thyroid patients find the thyroid medicine that is right for them?

Starting Points

  • Work with your provider to determine what formulation is effective at getting your levels into the optimal range.
  • Find the formulation that brings you as close to your “normal” as possible. If you still don’t feel quite right, keep looking!
  • Work with your provider to find a medication that you can tolerate, without unacceptable side effects.
  • Work with a doctor who has an open-minded approach to medication. Typically, MDs are less likely to be willing to prescribe Armour and other “natural” medications. Conversely, functional medicine practitioners and naturopaths are less likely to start off by prescribing Synthroid.
  • When choosing a medical provider, seek someone who is willing to listen to and consider your input. It’s crucial to have a provider who will partner with you to find the right medication. This means someone who will respect your questions, concerns, and feedback about any medication you are considering, or have tried.


So now that we’ve addressed common thyroid medication falsehoods, let’s take a deeper look at the available formulations.

Finding The Right Medication Fit For You

Even though there are many similarities among hypothyroid patients, it’s worth noting that there are also differences. Every person is an individual, with his or her own unique body chemistry. There are a multitude of medication options, including T4 only, T3 only, and combination T4/T3.

Here is a breakdown of the various types of treatment options currently available to thyroid patients (including our thyroid formulation wishlist!).

T4 and T3 Combination Products

In truth, supplementing with a T4/T3 combination product dosed with the normal human 4:1 ratio of T4:T3 would be ideal! Unfortunately, there is not a true product on the market that closely resembles normal human T4 and T3 physiology. Though formulations may be marketed as “T4:T3 dosed in a 4:1 fashion”, this is not so in real life.

Most NDT products actually have much more T3 than T4. Most compounded T4/T3 products aren’t always dosed optimally either, taking into account prescriber error. Additional factors include how well people absorb the medicine, metabolize T4 to T3, and whether the body immediately disposes of or “inactivates” the medicine.

That said, options include: Armour, Nature-Throid, NP Thyroid, Thyroid USP, Westhroid, WP Thyroid, and Compounded T4/T3.

T4-Only Products

Because 80% of thyroid hormone produced normally by the thyroid gland is T4, many societies and guidelines support the use of T4-only formulations. Though many do well with conversion of T4 to T3 and don’t typically miss the additional 20% of T3 that the thyroid gland is suppose to produce, others do not do as well.

T4 only options include: Synthroid, levothyroxine, Levoxyl, Tirosint, Unithyroid, Levo-T, and L-thyroxine.

T3-Only Products

Sometimes patients need isolated T3 help and are prescribed T3 formulations only. Most of the time T3-only products are added to T4 only products in an attempt to mimic normal human thyroid production. Because T3 is 3-5 times as strong as T4, dosing needs to be performed correctly to avoid hyperthyroid symptoms.

T3-only options include: liothyronine and Cytomel.

So how do you know what type of medication is right for you?

Unfortunately, there is no questionnaire you can fill out or blood test you can take that can answer this. Working with your thyroid provider and finding the right thyroid medicine can be a bit of a journey. Make sure that as you progress through the different options you give the formulation a fair chance and weigh its efficacy only once it’s dosed correctly (as it may be incorrect dosing rather than the actual medicine to account for your symptoms).

It takes a lot of patience to find your “right thyroid fit”, but it’s worth it to ensure a lifetime of optimal thyroid health.


Lastly, what do fillers have to do with anything?

In addition to differing amounts of active ingredients, each thyroid replacement option also has a list of different fillers that can cause side effects in sensitive individuals. Fillers are substances within the medication capsule that influence the stability of the thyroid medicine and can influence your body’s absorption of the medication. The most commonly reported side effects from medication fillers include rash, bloating, nausea, diarrhea, and headache. A list of common fillers that may cause human allergies or sensitivities are listed in the table below.

Are you sensitive to fillers in your thyroid medication?

Charts excerpted from What You Must Know About Hashimoto’s Disease(c) 2019 by Brittany Henderson, MD and Allison Futterman. Used by permission. Square One Publishers (www.SquareOnePublishers.com).

Some pearls of wisdom regarding thyroid fillers

  • People who have known filler, additive, or food sensitivities should consider starting with NP Thyroid, Tirosint, or Levoxyl (i.e. these are formulations that don’t have as many fillers).
  • People who are allergic to gluten should avoid specific forms of levothyroxine (generic) and Cytomel.
  • People who are allergic to dairy should avoid levothyroxine, Synthroid, Unithroid, Nature-throid, and WP Thyroid.
  • If your numbers are okay, but you’re not feeling right (and having symptoms such as rash, bloating, nausea, diarrhea, upset stomach, or headaches), approach your provider with the idea of switching to another formulation.
  • There are times when you can have a bad reaction to a medication, and the cause will not be the active ingredient—it will be because of a filler or dye. The best way to determine this is to try a different formulation to determine if symptoms resolve.
  • Dyes are another important factor to consider. If you have a bad reaction to your thyroid medicine, it may not be due to the active ingredient, but rather the dye that is used. If you believe you may be sensitive to the dye in your medicine (most dyes are in T4-only medicines), try the 50 mcg tablets as they are white and don’t contain dye. You can also consider Tirosint, the gel capsule form of T4, or NDT.
  • Finally, if commercial products fail you, consider compounded T4 and/or T3. Many times these can be formulated for your needs (including minimization of fillers and dyes). The downside? There is more risk for dosing error (human error) and compounded medicines are typically more expensive.

For some patients, finding the right thyroid formulation will be relatively simple. For many others, however, persistence is required. Although it can be aggravating to struggle with this issue, we want to encourage you to persist. Supplementing with the right medicine (for you) is an integral part of living thyroid healthy. Finding the correct thyroid formulations with acceptable fillers will allow you to live well with hypothyroidism.

You’re worth it!

About Brittany Henderson, MD, ECNU & Allison Futterman

Co-Authors of What You Must Know About Hashimoto’s Disease: Restoring Thyroid Health Through Traditional and Complementary Medicine.

Brittany Henderson, MD, ECNU is board-certified in internal medicine and endocrinology, with advanced training in thyroid disorders, including Hashimoto’s thyroiditis, Graves Disease, thyroid nodules, and thyroid cancer. Originally from Cleveland, Ohio, she graduated in the top 10% of at her class at Northeastern Ohio Medical University, where she received the honor of Alpha Omega Alpha (AOA). She completed her endocrinology fellowship training under a National Institutes of Health (NIH) research-training grant at Duke University Medical Center. She then served as Medical Director for the Thyroid and Endocrine Tumor Board at Duke University Medical Center and as Clinical Director for the Thyroid and Endocrine Neoplasia Clinic at Wake Forest University Baptist Medical Center.

She has received multiple prestigious grants from the American Thyroid Association (ATA) and ThyCa (Thyroid Cancer Survivors’ Association, Inc.). Her work has been featured on the cover of Thyroid and in many other scientific journals including EndocrinologyGut, and Oncotarget.

Her clinical practice is dedicated to patients with thyroid disease. She specializes in autoimmune thyroid disease, thyroid nodules, thyroid cancer, ethanol ablation, and advanced minimally invasive techniques. In addition to using a mainstream medical approach, Dr. Henderson also uses complementary medicine to explore underlying root causes of thyroid disease. Her clinical practice is located in sunny Charleston, South Carolina and is called The Charleston Thyroid Center.

Allison Futterman is a freelance writer who has been published in print and online. She’s written human interest, food, travel, profile, and writing craft pieces. Her work has appeared in Charlotte, Philanthropy, The Writer, Lake Norman Currents, and Winston-Salem Monthly Norman magazines, among others. Online, her writing can be found on the websites of “The Nervous Breakdown”, “Talking Writing” “People of Charlotte,” and “Brevity”. Additionally, she contributed to the Charlotte Observer for several years.

Allison is also a patient who has been dealing with chronic medical problems for many years. Chronic fatigue syndrome (CFS), fibromyalgia, frequent debilitating migraines, and, for several years, Hashimoto’s thyroiditis. After years of struggling with illness, she has found effective Hashimoto’s treatment and hope with the medical care of her co-author, Dr. Brittany Henderson.


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About Dana Trentini

Dana Trentini M.A., Ed.M., founded Hypothyroid Mom October 2012 in memory of the unborn baby she lost to hypothyroidism. This is for informational purposes only and should not be considered a substitute for consulting your physician regarding medical advice pertaining to your health. Hypothyroid Mom includes affiliate links including the Amazon Services LLC Associates Program.


  1. With all due respect, I am stating my opinions.
    Many patients and clinicians prefer to refer to NDT (Natural Desiccated Thyroid) as DTE (Desiccated Thyroid Extract). All thyroid hormone replacement is non-human. They are either natural or synthetic.

    Unfortunately, prior to use of THR, clinicians do not look at their patients’ T4 and T3 levels. Some patients, like myself, prior to TT, had/have high FT4 and low FT3 levels.

    Some clinicians are not permitted by the owners of their practices to test FT3 and/or script for DTE. Patients have to use non-endocrinologists to obtain their DTE. Many clinicians are not well-trained in testing Free T3 and use of DTE. This is a major concern and cause for the issues experienced by some patients that use DTE.

    Users of DTE that are well-informed, and through personal experience, find that they fair better when they start out a bit lower than their synthetic T4 dose, or start out at the DTE manufacturer equivalent, will experience “hypo” symptoms. Some patients start out too high, causing their bodies to not adjust to the added T3 in the DTE. They experience “hyper” side-effects. This does not mean DTE is not going to be good for them.

    Clinicians have to know what to test, when to test, how to dose. This includes testing DTE at 4 weeks after each change in dose (or brand), knowing that “in range” or “your levels are good” is not enough. Most of DTE users prefer to have the FT4 lower in range and FT3 higher in range.

  2. Thanks for all the information on thyroid medication. I started Levothyroxine about 5 years ago after my thyroidectomy. I was started on 150 mg. I did fine for a little while and then I was having a lot of emotional side effects. Getting depressed and crying all the time. I felt so silly being that I am not like that normally, which made everything worse. So after my next visit and some blood work the dosage ended up being way to high for me. My doctor lowered the dosage and then for a little while good again, until I started having a lot of headaches right in the top of my head, and it felt as though my heart was racing sometimes, and then I would feel exhausted. So she lowered my dosage again and I am now on 112mg, doing good so far. I never would have thought that the small mg difference would cause those kinds of symptoms. It is crazy how all this works.

  3. I’m on levothyroxine 75mg.i have gained weight.my doctor says it doesnt make you gain weight. But hello it as and it does.they dont care..I’ve never been this fat .my husband hates it .but I cant lose the weight..I am feeling alot better about 4 months ago I felt old ugly couldn’t get in to clothes I like .had to bye compfortable old lady cloths ..I dont understand all the tsh t3 t4.it should be on the packet..I wish they would listen to us the doctor s.cos we no how we feel cos our body’s tell us.but the doctor s which read the book.should see us regular and moniture.im sure then we might get good results.i mean we have to live with this for the rest of our lives. Yes

    • Karin Bolton says

      I am an RN who is ready to literally rip.out my hair due to frustration getting even diagnosed. Now that most of my thyroid labs have come back wnl my Internal medicine MD just insults me, ignores all my symptoms such as feeling cold all year long with the metabolic rate of a sloth! No matter what do Not give up! I feel horrible and so fat. I am going to go on Pentermine which is an appetite suppressant that has mixed side effects. So many doctors are indifferent. If they can not figure it out they either give up or get
      nasty. Either is totally unacceptable! You deserve more! If you decide to change MD’s and you probably do need to, I want to warn you to be very very careful. Call your insurance and let them walk you through the process. I lost a decent MD myself just because I asked for a
      second opinion. MD’s often have huge ego’s. The second MD I saw was horrible and even though I begged again and again my original MD would not see me.Try going on ask.com and write 10
      best Endochronologists in Clearwater
      And check every MD evaluation prior. I would reject MD who attended school outside the US. And Good Luck!.I will help.too.! Karin Bolton, RN.
      [email protected]. You deserve the [email protected]

  4. Hi I am Rizana I also with hypotairotxtile and I took the madicine is carbimazole now 4yrs it ds problem for me ? Pls give me a gd ansr

  5. Susan, pfizer can’t confirm that there is no cross contamination of gluten.

  6. I called and spoke with Pfizer on the phone and was assured that brand-name Cytomel is gluten-free .

    • Now one&half years I did not meet docter but I take the medicine its 5ml but1/2only I take per day .and I feel have a nothing problem but sum time I get deferent in my self dry skin hire falling.I am always feeling hot becomes black my body y dis all problem.

  7. Christina says

    Hello my name is Christina Jensen I have hyper throid issue,s very fed up with concate weight gain in face
    Stumach, butt have no energy and trying to get pregnant with babies help

  8. Penny blevins says

    Hi I had half of my thyroid removed 6yrs ago ever since then I am levothyroxine and I have gain weight .I am at 260lbs can’t focus no energy hair brittle at the ends my hearing has been affected by it . I have tried everything to lose weight. Went back to my doctor and said everything is fine when I know its not working. Can you help me with this problem of having a half of thyroid ? I would love to lose to this extra weight and feel good again.

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