Informational Posts

What Is NDT/What Is Armour?

What Is NDT/What Is Armour?
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Originally published on 4th January 2016
Last updated on 2nd November 2018

NDT (natural desiccated thyroid) is one kind of thyroid medication, often deemed the most effective by thyroid patients who have tried both T4-only synthetics (such as Levothyroxine or Synthroid) and NDT. 

Thyroid UK did a survey in 2015 which demonstrated that their respondents had the best success rate with NDT. But is it for you?

What is NDT?

Natural Desiccated Thyroid (NDT) contains porcine thyroid gland (though limited bovine brands are found), available on prescription in the UK on a named-patient basis (though often isn’t easy to get), as well as meeting the guidelines of the US Pharmacopeia. NDT medications are available in most countries through a doctor or medical professional. However, some thyroid patients take to self-sourcing over the counter brands (which is obviously not ideal and carries with it a lot of risks).

There are many different brands of NDT, including:

  • Armour (prescription)
  • Erfa (prescription)
  • Naturethroid (prescription)
  • NP Thyroid (prescription)
  • WP Thyroid (prescription)
  • Westminster (prescription)
  • Thyroid-S (over the counter)
  • Thiroyd (over the counter)
  • Nutri-Meds (over the counter Bovine)
  • ThyroGold (over the counter Bovine)
  • Thyrovanz (over the counter Bovine)

all of which can be compared here.

How Long Has NDT Been Around?

NDT has been used to treat hypothyroidism for over a hundred years. Interesting history about its use is mentioned in various books, and I’ve covered it all in great detail here.

Why is NDT so Popular?

Unlike synthetic T4-only medicine such as Levothyroxine and Synthroid,  which have left a lot of patients unwell due to conversion issues, NDT gives you all the hormones your own thyroid (if it was healthy) would be giving you; T1, T2, T3, T4 and Calcitonin, skipping the need for conversion.

The only difference is the ratio of each thyroid hormone in NDT compared to a healthy human thyroid gland, which differ slightly, as porcine thyroid gland preparations typically contains more T3 than its human counterpart.

As Thyroid UK report from their 2015 patient survey here:

“Levothyroxine treatment provided total relief of symptoms in 7% of the respondents and significant relief in 41% of respondents. However, 6% of respondents received no relief from symptoms and 40% only slight relief.
NDT provides the most relief of symptoms providing 29% with a total relief of symptoms and 57% with significant improvement. However, 10% only received slight relief and 2% no relief of symptoms.” [1]

I have often said that NDT has given me my life back due to how much better it works in my body compared to Levothyroxine. It eliminated all my symptoms. You can read more about this in my book.

A study in 2018 also showed that Levothyroxine was associated with a lower quality of life in those with Hypothyroidism. [2]

What Brands Should I Get?

One brand is not necessarily better than another – it depends on what works for you. Some people can be allergic or sensitive to binders or fillers in certain brands.

As well as the standard porcine NDT, there is also bovine desiccated thyroid products available, although far weaker in strength, which people often report needing a lot more of compared to porcine NDT. These are listed above.

It is important to stress that the ideal situation would be for your doctor to prescribe you this medication, although I appreciate that for some thyroid patients, they feel that self-sourcing is their only option after exhausting all other routes.

I do recommend exploring every avenue possible to have NDT prescribed for you before deciding to go ahead with self-sourcing. And if you do go ahead with it, at least inform your doctor and have them work with you in using it. They may even change their mind and prescribe it after all. My NHS GP supported me being on self-sourced NDT until I got it privately prescribed.

How Do I Change From Taking T4-only Medicine (Like Levothyroxine or Synthroid) To NDT?

People who switch from T4-only meds to NDT tend to take their T4-only medicine, e.g. Levothyroxine, for one a final day, then start on NDT the next day with a safe beginning dose. Your doctor should be managing you in this. The Stop The Thyroid Madness book contains information on dosing too.

So, is NDT The Best Thyroid Medication?

It’s not as simple an answer as you think. The ‘best’ medication is what works best for you, and that you feel comfortable on. Synthetic T4, Synthetic T3 and NDT all work well for different patients. Read my article about the different types of thyroid medications here.

You can read about my experience of changing to NDT here. If you’re struggling to find a doctor who will prescribe alternatives to just T4-only medication, you could also try asking your pharmacist if they know any doctors who prescribe them.

Have you tried natural desiccated thyroid medication?

You can click on the hyperlinks in the above post to learn more and see references to information given.




About Author

Rachel Hill is the highly ranked and multi-award winning thyroid patient advocate, writer, speaker and author behind The Invisible Hypothyroidism. Her thyroid advocacy work includes writing articles, authoring books, producing her Thyroid Family email newsletters and speaking on podcasts and at events about the many aspects thyroid disease affects and how to overcome these. She is well-recognised as a crucial and influential contributor to the thyroid community and has a large social media presence. Her bestselling books include "Be Your Own Thyroid Advocate" and "You, Me and Hypothyroidism".


  • Sarah R Christman
    January 24, 2020 at 3:47 am

    I got diagnosed with Hypothyroidism at a young age. I was in middle school or high school. While in high school I was having a lot of issues with levothyroxine and not being able to get my levels balanced. I was having terrible symptoms of hyper then hypo. So I did my own research and found out about the Armour thyroid. I brought it up to my doctor, and stood firm that that is what I wanted to try so she prescribed it. I am still on NP thyroid and it’s been 8-10 years now. My body just couldn’t handle the synthetic stuff, which I have since learned is probably because my body is super sensitive when it comes to meds. I’m super grateful for NP thyroid. I still get flare ups, and my levels still go out of whack at times (like it is currently), but overall NP thyroid is kept my symptoms and levels way more balanced.

  • Caz / InvisiblyMe
    November 3, 2018 at 5:52 pm

    I wish I’d seen this years ago when I was struggling with understanding different thyroid meds (and moved from Levo to NDT, purchased online from another country as the UK NHS woulnd’t prescribe). Very useful post as always, Rachel!

    • Rachel Hill
      November 3, 2018 at 8:00 pm

      Hi Caz, didn’t know for sure if you had hypothyroidism!


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