Updated as of August 2025
As a Naturopathic Doctor focusing in thyroid health, I get asked about Natural Desiccated Thyroid (NDT) almost daily—by patients looking for answers and by colleagues seeking clarity. With years of clinical experience, advanced training (both learning and teaching!) and a practice dedicated to helping people with hypothyroidism and Hashimoto’s, I’ve seen firsthand how confusing the world of thyroid medication can be.
That’s why I’ve put together the top 5 things you need to know about NDT. My goal is to clear up myths, explain how it really works, and give you the confidence to have an informed conversation with your healthcare provider.
1. What is desiccated thyroid? (NDT)
NDT is a prescription medication used for the treatment of hypothyroidism (low thyroid function). NDT is considered a combination therapy, as it contains both T4 and T3. It’s often referred to as a more ‘natural’ form of thyroid medication by many because it is sourced from porcine (pig) thyroid glands and therefore contains the whole spectrum of thyroid hormones. Unlike natural thyroid “extracts” you might find online or in health food stores (which should be avoided due to safety and quality concerns), NDT is a regulated pharmaceutical. NDT can be used as an alternative or in addition to the commonly prescribed synthetic thyroid medication levothyroxine (T4).
2. What is the difference between NDT and levothyroxine (Synthroid)?
Levothyroxine (Synthroid, Eltroxin) is a synthetic form of T4, which is the primary thyroid hormones your body makes. NDT, on the other hand, contains the full spectrum of thyroid hormones—T4, T3 (the most metabolically active hormone), and perhaps even smaller amounts of T1 and T2. For most patients, the benefit of NDT is the addition of T3, which most prescription thyroid hormones lack.
3. Where can I get desiccated thyroid?
NDT is available only by prescription.
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In the US: It’s often known by brand names such as Armour Thyroid or Nature-Throid. Currently (August 2025) there are concerns about the FDA removing NDT from the drug list which will impact patients ability to access this medication. If you live in the US and are concerned your continued access, please contact your prescribing doctor.
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In Canada: There are two options—ERFA Thyroid (available at most pharmacies in fixed doses of 30mg, 60mg, and 125mg) and Compounded Desiccated Thyroid (made by Medisca, available only through compounding pharmacies in capsule form). There is currently NO reason to worry about access to NDT in Canada.
Which NDT do I prescribe?
In my practice, I primarily use the commercially available ERFA Thyroid. This is for a few reasons: more widely available, lower costs, and equally effectively! In some situations I will use the compounded form (ex: allergies to commercial brand).
4. My doctor says desiccated thyroid isn’t safe, is that true?
Historically there were concerns about NDT doses not being standardized, meaning that one pill could have different amounts of hormone than the next. This was a valid concern back in the 1970s… but today NDT is produced by one commercial manufacturer (ERFA) in Canada and like any other pharmaceutical, it has a drug identification number (DIN) which means that it has been reviewed and approved by Health Canada. This also allows for quality control, inspections, and all the other regulations that go along with any pharmaceutical drug. There ARE unique risks that come with T3 medications like NDT, most of which are a result of being over medicated (taking too much). Proper prescribing, monitoring via lab work, and regular follow ups with your health professional are always essential.
5. Is desiccated thyroid better than Synthroid?
It all depends on the individual. I don’t believe (and the data doesn’t support) that EVERYONE needs to be on NDT. Some people thrive on T4 only medications like levothyroxine. The literature suggests that there is a percentage of people (5-15%) on levothyroxine that DON’T respond well, and continue to experience symptoms of hypothyroidism even with ‘normal’ lab work. I believe it’s this population that has the most to gain by trying a combination approach.
What I see in practice
After years of prescribing and working with desiccated thyroid, I can say that a large percentage of my patients who were feeling poorly on levothyroxine, notice some level of improvement on NDT. This could look like improvements in energy, body temperature, hair growth, sleep, skin, mood, metabolism, and other related symptoms. Many of my patients notice a difference in as little as 1-2 weeks, and symptoms continue to improve over the course of 3-6 months while we finesse their dose.
Bottom line: NDT can be life-changing for the right patient, but it’s not a one-size-fits-all solution. The best thyroid treatment is the one that helps you feel your best.
Have more questions about NDT or thyroid treatment options? Ready to explore whether NDT is right for you? Reach out to book a consultation.
Your Thyroid ND
Dr. Katie Rothwell, ND
Resources:
Hoang TD et al Desiccated thyroid extract compared with levothyroxine in the treatment of hypothyroidism: A randomized, double-blind, crossover study. J Clin Endo Metab 2013;98:1982-90. Epub March 28, 2013.
ERFA Pharmaceuticals www.eci2012.net/product/thyroid