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, America’s Pharmacist

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? Here’s how from my book Thyroid Healthy.

Check Morning Basal Body Temperature for Thyroid

Here is page 52 of my book Thyroid Healthy. 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. She devotes time to educating people about the benefits of natural vitamins, herbs, and minerals. In addition to writing a syndicated health column, “Dear Pharmacist,” which circulates to 20 million readers each week, Suzy Cohen is the author of many different books on natural health. You may have seen her on The Dr. OZ Show (6 different appearances), The View, The Doctors, Good Morning America Health, and hundreds of morning shows.

Suzy’s articles and quotes have appeared in major publications such as Woman’s Day, Reader’s Digest, OK Magazine!, First for Women, Fitness, Natural Health, Better Homes & Garden and dozens more.

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

About Dana Trentini

Who knew that little butterfly-shaped thyroid gland at the base of my neck could affect my life so completely? I founded Hypothyroid Mom in memory of the unborn baby I lost to hypothyroidism. Winner of two 2014 WEGO Health Activist Awards: Health Activist Hero & Best In Show Twitter. *Hypothyroid Mom includes Affiliate links. Connect with me on Google+


  1. Roberta Petricek says:

    I need help. I recently went on armour thyroid but really don’t feel any better. My 2 sisters felt immediately better. I need to find a specialist in the pittsburgh area who knows about all these combinations u duscussed. Roberta ([email protected])

  2. My Dr claims he has never heard of it (Armour) and refuses to look into it for me- says my feeling crummy is all in my head.. wish I could find a dr to listen!!!

    • Call your pharmacist, and if no luck there start calling surrounding pharmacies and ask what doctors are prescribing Nature Throid, NP thyroid, WP thyroid and Armour. It’s the easiest way to find an open minded doctor. Don’t be stuck on Armour though. They have raised their prices considerably since they were bought by a different pharmaceutical company. The other brands I mentioned are the same or better with less filler and the exact same active ingredients. I switched from Armour to NP, my sister switched from Armour to Nature Throid when the price jumped from about $10 to $45. Good luck!

  3. Hello! What do you recommend if I’ve had my thyroid tested several times, my thyroid is swollen (goiter), I’ve got scalloped tongue, can’t lose weight even though I run 20 miles a week, surgical menopause on HRT, my temp is never higher than 97.2, and besides having an AutoImmune Disease Ulcerative Colitis for 12 years, and my TSH and T3 Free are not optimal but considered ‘normal’. Do I find someone to listen to me or just chalk it up to coincidence?

    • Oh and I don’t know if the fact that my mom had a pituitary tumor and that I had hyperparathyroidism (removed 2.5 of my parathyroid) have anything to do with any of this – oh and I have metabolic syndrome…

  4. my dr dose not listen to me he like to be in totally in control you are so lucky to have a good dr he didn’t not tell me to take it in the morning and he gives me estrogen also i been taking antacids thank-you for the information

  5. Hello!
    I switched to desiccated 3 years ago And immediately gained 15lbs… I was so confused because I thought it would help with my weight. .. I became pregnant about 5 months after switching and we lost our baby girl at 35 weeks to stillbirth. I’ve been gaining weight since her death. .. I’ve just had another baby girl 3 months ago. .. in so happy she’s here bit again. .not losing the weight. ..it’s a good 40 pounds… I don’t eat gluten, dairy. . Beef. .. refined sugars. .. I’m pretty healthy. I have a hunch its my adrenals after reading your site. .. but I do have hashis so I’m wondering maybe my body didn’t love ndt? I’d love some advice! ? Thank you! ♡ ps..I am breastfeeding!;)

  6. Is there a Dr in South Carolina who will prescibe Armor for me? So far I have not been able to find one. Suggestions would be great!

  7. Tammy mazzola says:

    Where can I find a doctor who will prescribe NDT ?

  8. Can one take armour & synthroid together?
    What’s a good combo of t3/t4 together?
    Thank you

  9. gail sullivan says:

    I was diagnosed as Hypothyroid in Jan. 1995. I was on Synthroid and then the generic for this for over 21 years. In May 2016 I was diagnosed with Hashimoto’s at age 70. I went on the generic for Armour and immediately my numbers went up-too high in 3 weeks. Now on a combo of Armour-15 mg. and Armour generic-30 mg. My numbers just came back where they should be. The good news is that I am losing weight. That is probably due to part thyroid meds and stress. My recommendation is to go to a Women’s Health Group. They should have a better understanding of how to treat thyroid issues.

  10. My doctor really listens to my symptoms and not just the numbers which I am thankful for. About a year ago we decided I needed to add some T3. He preference was levothyroxine and composed T3. Well my insurance won’t pay for compound meds and I could not afford it. So the next choice was Nature Throid so that I was getting T4 and T3. It has been a struggle finding a good dose. Recently my symptoms are worse. Weight gain, hair loss (enough I needed to cut it) and extreme fatigue, especially mid day. I have an apt coming up and I know my numbers do play a roll but I am wondering what advice you can give me to discuss with him? Is levothyroxine and cytomel something I should ask about it? I don’t think he cares for cytomel which is why we went to nature Throid. I do know he prefers levothyroxine and when I said I couldn’t afford the compounded T3 and what about cytomel he said no let’s try nature throid. I am so tired of being tired!! Thank you for any help or discussion points you can offer me!

  11. I just had my thyroid radiated in April. I was hyperthyroid, now am hypo. I am trying synthroid, generic brand. Was prescribed 5o mc, but was getting afib and weakness. I called my doctor and after some discussion I was permitted to drop to 25mc. I already take a beta blocker due to the hyper. thyroid condition that I was treated for and the higher dose of generic synthroid caused afib any way. I am very discouraged right now. Any help out there? I really would appreciate it! Thanks, Pat. PS Gaining weight, 8 lbs.

    • Michelle Carroll says:


      I got radiation back in 2014 and it was the worst decision of my life. After 3 wks of having radiation, my world turned upside down. I knew there was something not right. I experience my first panic attack it was horrible, I experienced panic/anxiety attacks alot throughout each day. My endo at the time didnt want to see me until Dec got it done in June of 2014, as he said it could take 3 mths to work. I was gradually getting sicker and sicker each day, I felt like someone was controlling my brain, I wasn’t me, I didn’t know who I was. This went on for 3 mths, with taking 5/10mg of neomercazole daily until I saw my endo. He then put me on 40mg of neomercazole, for a further two wks, I had enough, I went to A&E, endured 8hours of waiting, constant migraine attacks and literally feeling awful. Worrying I was going to die and not see my little boy again. Pleading with them to admit me, they finally gave it, and let me see a endo the following day. I was in hospital for a wk. That time of my life, I felt like I started in my own horror movie. Fast forward 8mths and I got a TT. I wish I did it along time ago.

      You are under medicated, and need more thyroid hormone. Have you ever considered a removal(TT)? The beta blocker mighten be helping things either. Your body is working so hard to keep up with the low thyroid hormones. I can relate so much to your situation, and a TT help alot, but due to the stress of it all, I now have adrenal fatique.
      Hope this might help.

  12. Hi,
    Have you hear of Thyrolar? It contains T3 and T4

    If you have I would like to hear your views on it.

  13. Shana Wehr says:

    I’d absolutely love to read your book, I have hypothyroidism and I take 150 MCG of synthroid daily. I’ve gained 60 lbs in a year and its absolutely killing me and making depression and anxiety a lot worse. I’d love to read what your book has to help with everything.

  14. My thyroid was radiated in 95. Was on synthroid for lot of years and changed Drs. He let me change to Armour. I could tell a difference then. I have a test once a year and have ask for certain test and he has them done and always normal. Have trouble with loosing weight. What do you suggest. I know normal may not be the optimal. How do I get this across to the Dr.?

  15. I had to have my Thyroid completely removed about two years ago due to an abnormal cell mass growth on the thyroid and chest area (Non Cancerous). Since that time, I’ve been taking 0.112MG Synthroid. I’m finding out that my (old ways) diet and daily routine is no longer enough to keep the weight off. I have also been experiencing Tinnitus in both ears, and joint pain in my shoulders and elbows. As a bass player in a worship band, these things matter. My focus and mind clarity has also seem to be changing as well.
    I’ve been searching lately for an alternative med to supplement or replace the Synthroid. I have talked to my family doctor about Armour and he said just stick to the Synthroid. Your article has given me the information that I was looking for. Thank you so much!

    • Michelle Carroll says:

      I had a TT nearly two years ago and levo just wasn’t for me. From nearly 5 years of being overactive and trying to get better after the TT, the stress has taken it’s toll on my adrenals, I thought it was the armour doing it to me then when I changed. I did a saliva test and it showed very high corsitol levels throughout. I am now starting natural supplements that my doc recommended. I also have low stomach acid which didn’t help things.
      Maybe levo just doesn’t suit you, many people who have TT need that T3 more than someone who has their thyroid. Stop the thyroid maddness is a great book, check it out.

Speak Your Mind