Which is Better, Synthroid or Armour Thyroid Medication

Which is better, Synthroid or Armour Thyroid Medication

Which is the best thyroid medication for hypothyroidism?

I am asked this question all the time and my answer is always the same, “It’s individual.”

While some do great on T4-only levothyroxine medications like Synthroid, commonly prescribed by mainstream doctors, many of us continue to feel horrible on these drugs. My life changed when I found an open-minded thyroid doctor who listened, really listened, to me and my symptoms. Careful trial and error with thyroid medication brands and dosages and I found my “sweet spot”. With stress, age, and the onset of perimenopause, my “sweet spot” has changed over time, and thankfully each time we find my new “fabulous”.

I take a combination of Nature-throid (a brand of natural desiccated thyroid) and a compound time-release T3 (created by a compounding pharmacy). Oh boy does dosage ever make a difference for me. I feel terrible when my Free T3 is low or even middle of the range. I feel fantastic when its at the top quarter of the normal range. Finding what is right for my body has been life-changing. I feel better today at 46 years old than I felt at 30…yes really. I hope the same for you.

Written by Suzy Cohen, RPh

When you’re taking medicine, eating properly and still suffering, you might begin to wonder if your thyroid medication is the problem. It’s a valid thought process. Medication should help you feel better.

I am often asked, which is the best medication to take, but there is not a simple answer to that because we are unique individuals. Because I have been a Registered Pharmacist for 26 years, and I’m a thyroid expert, I’m also asked “What’s the difference between Synthroid and Armour Thyroid?”

While both are used to replace thyroid hormone, the differences are pretty substantial. I’d like to share those now so you can make more informed decisions about what you take. I think this could really help you figure out how to make the most of your medicine, lab work, and dietary supplements.

Synthroid is a pure T4 drug and Armour Thyroid is an NDT drug (Natural Desiccated Thyroid) drug. The very names of these medications cause confusion.

From now on, whenever you read “T4” you can think of that as the same exact hormone that is secreted from your thyroid gland. Synthroid is just a T4 hormone that is a medication. It requires prescription, and your own thyroid gland makes this naturally. T4 is not active in the body, it has to be processed and turned into T3 which does all the good stuff.

Armour Thyroid is an NDT drug, which stands for Natural Desiccated Thyroid. It is a glandular medication that comes from animal sources. It combines T4 and T3 so sometimes people feel better on this because they are actually taking T3 hormone.

Pure T4 Drugs by Other Names
Synthroid is a very popular medication that is pure T4, but there are other names this medication goes by. For example, Levothyroxine, Levothroid, Unithroid, and Tirosint.

NDT Drugs by Other Names
Armour Thyroid is an NDT medication that combines T4 and T3. There are other brand names that work in a similar way that are porcine-derived as well. These include Nature Throid (which is gluten free), WP Thyroid, and Erfa Thyroid (from Canada).

There is also synthetic T3 (like Cytomel) and Compounded T4/T3 (created by specialty compounding pharmacies).

This is how Synthroid and Armour Thyroid differ
(They are different in 8 ways)

1. Synthroid is bio-identical to human T4 (thyroxine) hormone. Armour is derived from pigs, then purified, so it is not bio-identical to human thyroid hormone.

2. Synthroid is not derived from animals, it’s made in a laboratory. Armour is animal-derived and purified in a laboratory. More specifically, Armour is known as an NDT medication, short for Natural Desiccated Thyroid, and it is porcine-derived from the thyroid glands of pigs.

3. Synthroid contains T4 (thyroxine) only, whereas Armour contains both T4 and T3 (tri-iodothyronine). T3 is more biologically active than T4.

4. Synthroid’s actions may take a few hours, whereas Armour Thyroid will begin to work within an hour. What you should feel is more energy, some warmth if you are frequently cold, and more mental clarity. Your heart rate may increase a bit, but not to an uncomfortable level.

5. While possible, it’s unusual that Synthroid triggers an autoimmune response in a person with Hashimoto’s thyroiditis. Sometimes for people with Hashimoto’s their bodies ‘see’ the porcine-derived thyroid hormone and launch an attack against that because it is glandular. While rare, this explains why some of you with Hashimoto’s might feel a little better on Synthroid or a synthetic combo of T4 and T3 (such as taking a combination of Synthroid and Cytomel). It’s very individual of course. This is not a blanket statement, merely a consideration if you have Hashimoto’s and you feel worse on NDT drugs.

6. The inactive ingredients differ. Our bodies are all different in terms of sensitivities to these various ingredients which explains why some people react poorly to certain brands of thyroid medication.

Synthroid- Inactive ingredients include acacia, confectioner’s sugar (contains corn starch), lactose monohydrate, magnesium stearate, povidone, and talc.

Armour Thyroid- The inactive ingredients are calcium stearate, dextrose, microcrystalline cellulose, sodium starch glycolate and opadry white (colorant).

7. Synthroid may take approximately 4 weeks to cause any real alterations in your labwork, whereas Armour (and other NDT drugs) may impact your labwork within 2 weeks. Labs are usually drawn every month or two until symptoms have stabilized so expect to do a little trial and error.

8. Synthroid is measured in milligrams, Armour is measured as “grains” so if you switch between these medications, it’s difficult to figure out what dose you need. Later on in this article, you will find a handy list I created for you titled, Thyroid Hormone Dosage Equivalents. See below.

This is what Synthroid and Armour Thyroid have in common
(They are similar in 8 ways)

1. Neither one corrects auto-immune dysfunction they just help to restore thyroid hormone levels. This means that if you have an over-reactive immune system, it will continue to destroy your thyroid gland tissue despite the medicine you take. This is why there is more to Hashimoto’s than taking thyroid medication. Hashimoto’s is the number one cause of hypothyroidism, yet many hypothyroid patients have no idea because thyroid antibodies are not often tested in mainstream medicine.

2. They both have the potential to form Reverse T3 in your body. Both Synthroid and Armour Thyroid have the ability to create the hibernation hormone rT3 after you take them. If you have Reverse T3 levels that are high, the way to help yourself is not by changing medication, but rather by forcing the conversion of your medications in an active direction. Since T4 (thyroxine) can be metabolised in two directions, forming an active hormone, and an INactive hormone (rT3), it’s best to test yourself for levels of both free T3 and reverse T3.

Thyroid Hormone Conversion

3. Both medications are best taken in the morning because they produce energy, so if you take them at night, it could cause insomnia. (Although some people do great taking their medication before bed. We’re all individual. If you’re taking a T3 medication like natural desiccated thyroid, also speak to your doctor about whether splitting your dose so that you take half of your dose two times a day, for example half first thing in the morning and the other half in the early afternoon, instead of all at once might be more effective for you.) Both medications should be taken on an empty stomach.

4. For all practical purposes, the side effect profile is similar. Thyroid medications are stimulants so regardless of their brand name, they do the same thing. They turn on your fat-burning switch and they improve energy levels.

5. They both require a valid prescription in the United States.

6. Taking these medications will necessitate the need for the same exact lab tests.

7. Neither medication will prevent the development of thyroid cancer, one of the fastest growing cancers in the world. These medications are not anti-cancer, they are hormone replacement drugs.

8. Drinking coffee within 30 minutes of these drugs might significantly reduce their effectiveness. Wait at least one hour before eating and at least three to four hours before taking any vitamin with iron including multivitamins and prenatal vitamin supplements with iron.

You have to convert medication for it to work

Synthroid doesn’t work until your body activates it. It is a T4 drug and your cells require T3 to effectively wake up, burn fat, and feel happy. So you have to convert the T4 into T3 and some medications get in the way of that. See below. Remember this point, if you’re low in T3 and you take a T4 drug, it’s like putting wiper fluid in your gas tank. It does you no good.

Medications interfere with conversion of T4 to T3

Some drugs practically put a STOP sign in front of T4 and prevent its conversion to T3 which is biologically active. Among the most common offenders:

Beta blockers


Oral contraceptives (pills, patches, shots, etc)

Hormone Replacement Therapy



Corticosteroids (Prednisone, Hydrocortisone, etc)


If you are taking any of these medication, you may feel better on an NDT drug because a T4 drug will not easily convert to T3.

Feeling good requires vitamins and minerals

Feeling good requires conversion of Synthroid (or any T4 drug) to its biologically active metabolite T3.

In order for you to convert a T4 drug into a biologically active form, you need several vitamins and cofactors. So if you’re taking Synthroid, for example, then it might be a good idea to have the following nutrients on board (to help drive the conversion into a biologically active form). You don’t have to necessarily supplement (ask your doctor to test your levels), you could try to eat a clean, healthy diet.



Vitamin A





Vitamin B6

Vitamin D


Cortisol levels

Having imbalances or deficiencies of these nutrients can prevent your ability to get well. Many people don’t realize that acid-reducing medications, estrogen-containing hormones, benzodiazepines, opiate analgesics, blood pressure pills, diuretics, statins, even coffee and wine could deplete levels of these nutrients, thus getting in the way of you feeling good. It’s what I call the Drug Mugger effect, based on the title of my book Drug Muggers: Which Medications Are Robbing Your Body of Essential Nutrients–and Natural Ways to Restore Them. If you take any of those medications, you might need to supplement with the above nutrients if you take a T4 drug. It’s a conversation to have with your physician because you might feel better on a pure T3 drug, a combination of T4 and T3, or NDT options.

Iron deficiency, for example, leads to very poor T4 to T3 conversion, so you become clinically hypothyroid which slows metabolism. The net result is weight gain.You may think you’re tired because you have low iron, and less oxygen is carried around your body, but you’re probably not terribly anemic, it’s more likely that you are “thyroid sick” due to poor T3 activity. Take a look at all the drug muggers of iron on page 89 of my book Thyroid Healthy.

Drug muggers of iron

So what is the right dose of medication?

Your dosage is based upon several very important factors, it’s not a one-size-fits-all. Initially dose determination should be based upon:

1. Your age
2. Other health conditions
3. History of heart problems
4. Other medications you take which might interact
5. Severity of symptoms that you’re facing
6. Length of time you have been chronically ill
7. Laboratory tests that evaluate T3, T4, rT3, TSH, and antibody levels to TPO and TG
8. Morning basal body temperature

Have you checked your morning basal body temperature?

Check Morning Basal Body Temperature for Thyroid

Here is page 52. Get a copy of your lab results and check that you’ve had all these tests done and that your levels are optimal not just normal.

Suzy Cohen's book "Thyroid Healthy"

Most of you will begin a medication dose and based upon how you feel, you will either increase or decrease your dose. Hopefully you have a doctor who listens to you and your symptoms. If you develop palpitations, sweating and insomnia, you are taking too much. If you still feel cold, tired and remain overweight, you might need a higher dose, or a second dose during the day. Dosage changes should always be discussed with your physician. There will be times when you will go through life and have to increase your dosage. It’s hard to know exactly, but here’s a good rule of thumb.

When to increase dosage

Based upon labs, if your free T3 is low, you might need Cytomel or Compounded T3 or NDT.

Big life changes, maybe you’ve moved or lost your job, maybe you had a baby.

During a crisis, you may need more adrenal support, you cannot have thyroid problems all by itself. The thyroid and adrenal work together.

After surgery, it’s very common to need more medication or supplemental support.

Keep in mind we are all unique and we have various sensitivities. Please don’t ever double up on your medication, that is dangerous. If you forget a dose, do not double up, just take it the next day when it is due.

Thyroid hormone dosage equivalents

NDT porcine-derived drugs like Armour Thyroid are measured in “grains” not milligrams.

T4 drugs like Synthroid are measured in milligrams.

It’s sometimes difficult to figure out what you are taking, and how your dose has changed if the doctor alters your medication. The following chart might come in handy.

Thyroid hormone dosage equivalents

What if you’re doing everything right, and you still feel bad?

If you are taking thyroid medication, and still not feeling well, one big secret is that your adrenal glands are still not nourished. Your recovery will go faster if you think of your adrenal glands whenever you think of your thyroid gland. These two organs are connected through the HPA axis, the hypothalamic pituitary adrenal axis. There is a connection that most physicians dismiss, and if you only treat your thyroid gland, your recovery will be slower, or incomplete. Ashwagandha is a wonderful adaptogenic herb that supports both thyroid and adrenal health. It also induces relaxation, so if taken at night, it could help with relaxation.

About Suzy Cohen, RPh

Suzy Cohen has been a licensed pharmacist for 25 years and is a functional medicine practitioner for the last 15. You may have seen Suzy on The Dr. OZ Show (6 different appearances), The View, The Doctors, Good Morning America Health, and hundreds of morning shows. Her supplement line called Script Essentials includes a supplement specially designed for thyroid disease called Thyroid Script.

READ NEXT: 10 Things That Stopped My Thyroid Hair Loss

Take Back Your Thyroid Health! Sign up and never miss a post - it's FREE

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. I am on np 15mg, and feel really great, no more brain frog, tons of energy, acing body pain all gone, also I lost 12 pounds. I walk, weight training, and some yoga, nothing new I always exercised that way, but now a lot more easily and good results !
    The only negative feeling, is that I am easier out of breath, breathing harder!

  2. Hi, i’ve been trying to find this out. I’ve been googling it to no avail. Is compounded armour capsules in anyways different than armour tabs other than the fact it is slow release . Ie..diff makeup/chemicals?
    I will ask my pharmacist when I see them today. They’re telling me that he can’t get any T4 powder so they will be giving me the tablets. I take 45 mg w/the compounded, so now they have to give me 2 pills, 15& 30 to equal my 45. More expense too.

  3. Rosa hornbuckle says

    What’s the name of the thyroid book and who is it by and what is it called.

  4. Rosa hornbuckle says

    I need help really bad I am looking for a Dr in Birmingham Alabama that is good listening to the patient symptoms and body issues so I can be put on the correct Med. I had a complete thyroid removal and every since then body had not been the same brain fog hypothyroidism wait gain bad tired no energy body pain all over and was dx with show-gen dz and fibromyalgia which fibromyalgia started when I started this medication levothyroxin but no Dr will listen to me and I also read if taking levothyroxin and you have a autoimmune dz levothyroxin will cause your body to hurt all over. Any Dr could help me. If anybody knows anyone please advise me.

    • Marlo Horne says

      Dear Rosa,
      Mary Shomon, a patient advocate who writes about thyroid problems, has a couple of websites that include the following:

      Just continue to page down through the website, and you will find several doctors listed for Birmingham. I am not sure how current this list is and the first doctor does not look to be easily available. Just keep paging down the webpage to find other doctors. I think you will want a doctor who will prescribe Armor, which can also be made at a compounding pharmacy.

      As explained above by Suzy Cohen, Armor is a natural thyroid supplement from desiccated pig thyroids, consequently it has a combination of the hormones you need, T3 and T4. T3 is the active hormone that is used directly by organs in the body; whereas T4 has to be converted by the organs into T3.
      Synthroid is a synthetic thyroid supplement, which only has the T4 hormone. In your case, that would force every organ in your body to convert T4 into T3 before any of it could be used. Armor also has T1 and T2, hormones that may still not be well understood, but I would hate to do without them.

      My mother had most of her thyroid removed in her early 30s. By finding a doctor on Mary Shomon’s website, she was able to get a prescription for the Armor thyroid she needed to properly maintain her thyroid hormone level for the rest of her life (age 89).

      I hope this helps and I will be glad to correspond further.

  5. In my Naturopathic practice, women clients with seeming thyroid issues almost without exception had either stressed or weak adrenals. There is a synergy between the thyroid and the adrenals that must be maintained in order to attain balance and elimination of symptoms. An effective adrenal supplement must have Vit. C and pantothenic acid(B5)in the formula. When you are stressed you are burning up vitamin C. If testing shows the adrenals to be severely depleted, you may need to take a glandular adrenal supplement (dessicated adrenal glands) to rebuild the gland.

  6. I had thyroid cancer and thyroid was removed over the summer. I was on Synthroid for almost 18 years before this for Hashimotos. Six weeks after thyroidectomy I switched to Armour (about a month ago). I think that desiccated thyroid is a better fit for me overall, and Armour was great except that it was causing me significant headaches, especially when it was increased from 90 to 120 (I was gaining weight while eating a very strict diet). So I am just today starting Nature throid. I am hoping that this one works, but slightly concerned when I read stuff online. What does it mean to go to a compound pharmacy to get a desiccated thyroid powder? How do you do this? Do you ask the doctor? Thank you so much.

  7. Elizabeth M. says

    I have been on armour for at least five years. Wasn’t feeling that great and my doctor put me on Synthroid which I didn’t really want to do. I was on 90 mg of armor and she put me on 175 mg of Synthroid. I thought that was very high but she said 175 is the same as 90 armor… Wish someone would tell me if that is right!

    • I have been on Nature Throid for six years now, my t4 remains at 61-65. My new doctor is now changing my medications to levothyroxine 50 mcg tablet. When I was first told I had hashimoto’s hypothyroid I was put on synthroid, which made me feel so bad, gained weight, anxiety, chest pain, etc. But my new doctor said, this will be better for me. I am very nervous about switching due to the past side effects. Being that I honestly have not gotten better even with Nature Throid, wondering if I should slowly take myself off of all pills?

  8. Elizabeth says

    I’ve been on Nature thyroid for some time now. I’ve been having rapid heart-rate recently so my func. dr. lowered the dose from 113.5mg. to 97.5mg. and I’m still feelingit. I went to my “regular” pcp who put me on a beta blocker. I still feel sick. I live in The Villages, FL so wondered if I need a new func. dr. (which are hard to find) and if you can make recommendations on who to go to. Any recommendations (and I mean any) would be appreciated.

    • Hi Elizabeth, Speak to your doctor about the fact that Nature-throid was not available for several months and now the new pills seem to be different. I have heard from several Hypothyroid Mom readers reporting not feeling well on the new pills. I personally decided to switch to desiccated thyroid powder compounded by a compounding pharmacy because I had a feeling the new pills of Nature-throid might be a problem for me. I had this experience back in 2009 or so when Armour was changed and my symptoms started returning. Worth speaking to your doctor about this.

    • Medicare just started covering Armour Thyroid!!!

      • Pam Webner says

        I was just told that Medicare doesn’t recognize Armour, I have been on it for years, now Iam scared I may have to change to synthroud or the generic form of it. But, I do believe I can still be on Armour just pay the full price, which I probably should do. Any thought?

        • Hi Armor Thyroid is made from Allergan company. They have a patient assistantance program if u can’t afford your meds u can get it for free if u qualify. I would give them a call.

  9. I’ve been on Synthroid for 10 years. During that time I went through menopause and began losing my hair – all over my body slowly. I was told it was age related. I also suffer from insomnia. I need a referral for a doc in the Atlanta area that will consider Armour and has a healing philosophical approach to his/her practice. I would sincerely appreciate any recommendation as I’m sick of feeling sick and tired. 🙂 Thanksso much!

    • Juliem—— you need to go to Southeastern Endocrine and Diabetes in Roswell. I have gone there for years ( I am 40 with Hashimoto’s) and they LISTEN to how you feel. I am gaining weight at the speed of light despite my efforts and basically feel like poo… so he listened and I am going on NP thyroid tomorrow and giving it a whirl! I see Dr. Munoz or the NP Donnie Jester. Both are great! Sorry it is so late for a reply!

  10. Geri Latina says

    Thank you!!!

Speak Your Mind