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(Important Note: This article is an August 2025 update of a story originally covered in 2022.) The majority of people with hypothyroidism take levothyroxine – the synthetic form of thyroxine (T4). But in the United States, 1.5 million prescriptions were written in 2024 for patients taking natural desiccated thyroid (NDT) as their primary thyroid hormone replacement drug.  The majority of these patients have already tried levothyroxine unsuccessfully in the past, and eventually found optimal thyroid hormone replacement and symptom relief on NDT. 

In August of 2025, the FDA issued groundbreaking news about the future of NDT, and these developments may affect availability and affordability of NDT medications for the thyroid patient community. 

Ahead, we answer the vital questions about these developments.

Natural desiccated thyroid (NDT) drugs are thyroid hormone replacement medications derived from porcine (pig) thyroid glands. The best-known brand is  Armour Thyroid, manufactured by AbbVie (formerly Abbott Labs). The other NDT currently available in the US is NP Thyroid, made by Acella. There are also several generics with limited availability, from manufacturers ALI and ANI. (Two popular brands that were formerly available, Nature-throid and WP Thyroid, manufactured by RLC Labs, are currently not in production/distribution.)

NDT medication has been used as a hypothyroidism treatment for over 100 years. Because these drugs were in widespread use long before the Food and Drug Administration (FDA) began approving drugs in 1938, NDT medications were “grandfathered.” This means that there were allowed to be prescribed and sold right away, without going through a new drug application approval process. For decades, the FDA never requested they go through the formal approval process.

In 2022, the FDA made the controversial decision to designate NDT as a “biologic” drug. The FDA decreed that to legally market and sell NDT, each NDT manufacturer would need to go through an approvals process known as Biologics License Applications (BLA) or it will be against the law to sell or market the drug. In 2022, the FDA said that the deadline for the biologic approval of NDT would be in 2029, allowing 7 years for NDT manufacturers to file and go through the lengthy BLA process. 

In a move that was reportedly a surprise to some NDT manufacturers, on August 6, 2025, the FDA publicly issued an action notification, and sent a letter to all NDT manufacturers. 

The letter repeated the FDA claim that NDT is being designated as a biologic drug, and that manufacturers will need BLA approval from the FDA to continue marketing the drug in the U.S. But instead of an enforcement date in 2029, the FDA moved the deadline for approval to a period of “1 year.” This mean that after August 2026, any NDT drug that has not successfully gone through the FDA’s BLA process would become unavailable. 

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A biologic is sometimes called a biological product or biological agent. While these terms may be unfamiliar, you’ve no doubt heard of popular biologic drugs for autoimmune diseases –like Humira, Remicade, Enbrel, and Skyrizi.

According to the FDA, a drug designated as a “biological product” is “a virus, therapeutic serum, toxin, antitoxin, vaccine, blood, blood component or derivative, allergenic product, protein, or analogous product, . . . applicable to the prevention, treatment, or cure of a disease or condition in human beings.”

While the FDA has determined NDT to be a biologic, this is based on the presence of thyroglobulin, a protein, which is found in small amounts in NDT. The active therapeutic ingredients are the natural forms of thyroxine (T4) and triiodothyronine (T3) in NDT, not thyroglobulin.

The FDA believes that NDT meets the definition of a biologic because it is derived from the thyroid glands of pigs. They also believe that the thyroglobulin in NDT should be considered a “protein” or “analogous” to a protein.

This decision is controversial, and most NDT manufacturers strongly disagree with the science behind the biologics designation. They also question the FDA’s justification for requiring a BLA for NDT. Most currently available and approved biologic drugs are given as injections or infusions, not oral tablets like NDT.

Interestingly, AbbVie – the manufacturer of Armour Thyroid – has not publicly opposed this development. It’s thought that they may be one of the companies that has already begun the behind-the-scenes work needed to file for approval for Armour as a biologic drug. At present, it’s not known when AbbVie will submit its BLA application for Armour. As a global pharmaceutical giant, AbbVie is, however, well-positioned to handle the costly and complicated BLA process for Armour. AbbVie is one of the world’s biggest pharmaceutical manufacturers of biologic drugs. Also unknown is whether the other NDT manufacturers will submit BLA applications for their NDT drugs, and if so, when that will happen.

Here are some other aspects of the FDA’s actions that make this development especially concerning and controversial for the thyroid patient and provider communities. 

At present, as of August of 2025, no NDT drugs have biologic approval, and no companies have filed a BLA application with the FDA.  This process typically requires from several years to a decade to prepare the BLA submission, and another 6 to 12 months for the FDA to approve the submission.

The FDA is saying they are allowing this 1-year grace period so that “doctors will be able to work with their patients to safely transition them to an FDA-approved thyroid hormone replacement medication.” (Currently, the only FDA-approved thyroid hormone replacement medications are synthetics, including levothyroxine (synthetic T4/thyroxine), and liothyronine (synthetic T3/triiodothyronine). Most patients who take NDT have already tried -- and failed on -- FDA-approved synthetic thyroid hormone replacement medication.

There’s no public information as to whether any companies have been conducting the preliminary research necessary to prepare a BLA submission for their NDT medications, or when they would be ready to submit a BLA application to the FDA. 

But given the current deadlines, there is a possibility that NDT will be taken off the market before an FDA-approved NDT drug is available for patients, leaving potential hundreds of thousands of patients without access to the thyroid treatment that they need. 

The biologics currently on the market are complicated to produce and are usually far more expensive than other medications. 

Most biologic drugs are either injectible or delivered via infusion, and the most popular biologics are used to treat a range of autoimmune inflammatory conditions—including rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, plaque psoriasis, Crohn’s disease, ulcerative colitis, and other conditions. 

They include: 

• Humira (adalimumab), made by AbbVie, with an average retail cash price per month of $7,500 (90,000 per year)
• Remicade (infliximab), marketed by Janssen Biotech/a Johnson & Johnson company, with an average retail cash price per month of $2,000 to $7,000 ($24,000 - $84,000 per year, depending on dose frequency.)
• Enbrel (etanercept), from Amgen (Immunex Corporation), with an average retail cash price of $8,000 per month ($96,000 per year.)
• Skyrizi (risankizumab-rzaa), from AbbVie, with an average retail cash price of $10,000 per month ($120,000/year).  

Here's the information for the two brand name NDT drugs, which are in tablet form: 

• Armour Thyroid (desiccated porcine thyroid), from AbbVie, average cash price of $60 per month ($720 per year). 
• NP Thyroid (desiccated porcine thyroid), from Acella, average cash price of $30 to $60 per month ($360 - $720 per year.) 

First, there’s no way to predict how much NDT medications will cost after FDA-approval as biologic drugs. However, it’s safe to assume that the cost of these will increase significantly.  Medicare and some insurers already refuse to cover NDT drugs, forcing patients to pay cash prices.  If prices rise significantly as anticipated, many of these patients will be unable to afford their NDT medication. 

Second, some health insurers do not have NDT drugs on their preferred formulary lists, and patients need to pay higher copays for these drugs. Biologic copays can be steep— often in the hundreds up to thousands of dollars per month. Some drug manufacturers offer copay assistance programs to help offset high copays for biologic drugs, but Medicare patients are not eligible for these programs.

Some patients have managed past shortages by ordering NDT drugs from outside the U.S., for example, Erfa brand NDT from Canada. Typically, the government has looked the other way at imports of small amounts of otherwise “legal” drugs for personal use. (And again, while NDT is currently not FDA-approved in the U.S., it is FDA-regulated, and legal to prescribe.) 

However, after the ban goes into effect, unapproved NDT will no longer be legal, so it’s likely that it will be difficult, if not impossible, to import NDT drugs from outside the U.S. 

If these medications would even be allowed into the U.S., they would also likely be subject to tariffs, which at that point could range from 100 to 200%. (As of August 2025, the expected tariff rates on drugs imported from other countries are still up in the air.)

Some thyroid patients take NDT, but not as a brand-name tablet. Instead, through trial and error, they found that they felt best on unique doses that are not available in standard tablet sizes, or needed specific fillers and binders in order to avoid allergic or sensitivity reactions. These patients receive prescriptions for compounded NDT medications, specially prepared by compounding pharmacies individually for each patient. Compounding pharmacies combine an active pharmaceutical ingredient (API) – in this case, natural desiccated thyroid powder – with other ingredients into a capsule form.

In September of 2022, the FDA sent a letter to the National Association of Boards of Pharmacy reminding them that NDT was designated as a “biologic” and not FDA-approved. The letter implicitly encouraged them to take action at the state level to ban the compounding of NDT drugs.

Based on this letter, the manufacturers of compounded NDT raw material, and some compounding pharmacies, initially considered halting all manufacturing and sales. But since that time, no state boards of pharmacy have taken action, so the manufacturers and compounders will continue to manufacture the ingredients for, and sell, compounded NDT for the time being.

At the same time, the compounding industry was actively fighting against the FDA’s actions legally and in the court of public opinion. The FDA has had a more widespread crackdown underway, attempting to limit or even eliminate the compounding of most medications, including bioidentical hormone replacement therapy. 

In the August, 2025 action, the FDA has explicitly stated that “these unapproved animal-derived thyroid medications are not eligible for compounding because these products are regulated as biological products under the Public Health Service Act.” 

It’s clear that the FDA considers compounded NDT as part of the overall ban to go into effect in 2026, and after that time, compounded NDT medications will not be available. 

‍If you currently take compounded natural thyroid, should you be concerned?

If you are taking compounded NDT, you should be aware that at any point before the 2026 ban goes into effect, your state board of pharmacy could still announce that they are banning compounded NDT drugs. It’s also unlikely that you will hear about it until after this decision has been handed down.

Paloma Health recommends that you talk to your doctor now about developing a contingency plan so you’re not surprised by any sudden developments in the availability of your medication.

You can read the summary of the August 2025 FDA action at the FDA website: https://www.fda.gov/drugs/enforcement-activities-fda/fdas-actions-address-unapproved-thyroid-medications 

The FDA also has a downloadable PDF of the August 6, 2025 letter sent to the various NDT manufacturers: https://www.fda.gov/media/188081/download   

You can read the FDA’s September 16, 2022, letter to the National Association of Boards of Pharmacy re: NDT compounding at
https://a4pc.org/files/MEMO-EO-FDA-Letter-re-DTE5.pdf.

1. SIGN the petition

Paloma has created a petition at Change.org. Please sign it to help show support, as together, we advocate with the FDA to protect the availability and affordability of NDT medications for hypothyroid patients. 

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2. CALL and write your Member of the House of Representatives and Senators 

Visit https://www.congress.gov/members/find-your-member and type your address into the search box. You’ll get your representative’s names and contact information – including phone and mailing address. 

You can call the Capitol switchboard at (202) 224-3121 to be connected to your member’s office.

You can also use https://democracy.io to easily send emails to your Congressional Representative and Senators.

Message: Make your legislators aware that the FDA is taking a drug that has been safely used for 100+ years OFF the market, and attempting to force you to take synthetic drugs. Share your story! For most of you taking NDT, you've already unsuccessfully taken synthetic thyroid drugs in the past and they have failed to treat your hypothyroidism!

3.CALL and WRITE the FDA

Call the FDA’s general information line at 1-888-INFO-FDA (1-888-463-6332) and also contact the FDA Ombudsman at 301-796-8530.

You can also reach out to the FDA at the following email addresses: 

FDAADVISORY@fda.hhs.gov 

Industry.Biologics@fda.gov 

druginfo@fda.hhs.gov 

ombudsman@oc.fda.gov 

Message: Make the FDA officials aware that you have already done “step therapy” on levothyroxine drugs, and they failed to treat your hypothyroidism! Tell them the symptoms you experience taking levothyroxine. Urge the FDA to extend the deadline for enforcement until after an affordable FDA-approved NDT is on the market! 

4. SUBSCRIBE to Paloma’s free updates

If you want to make sure you don’t miss any news about the NDT situation, grab a discount coupon below for Paloma's complete home thyroid test kit, and you'll be signed up for our newsletter.
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As a nationwide medical practice focused on hypothyroidism treatment, Paloma is closely monitoring the situation regarding natural desiccated thyroid, and our network of physicians are staying up-to-date on options for patients. We are also committed to protecting patient access to affordable natural desiccated thyroid as a treatment option. If you would like to work with a knowledgeable doctor for your thyroid care and to develop a personalized plan for optimal hypothyroidism treatment, or develop workable contingency plans for any potential shortages or bans on your thyroid medications, we invite you to schedule a virtual consultation with one of our experienced thyroid care providers.

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• The FDA has moved the deadline for NDT biologic approval from 2029 back to August 2026, after which unapproved NDT will be not be legal in the U.S.
• NDT, derived from pig thyroid glands, has been used for over 100 years and is preferred by many hypothyroid patients who do not respond well to synthetic drugs like levothyroxine.
• As of August 2025, no manufacturer has completed the lengthy Biologics License Application (BLA) needed for continued U.S. sales.
• The ban will also eliminate compounded NDT and likely block imports from countries like Canada, India, and China.
• Prices for biologic-designated NDT could rise sharply, with limited insurance coverage, high copays, and no coverage or copay assistance for Medicare patients.
• Patient advocates are urging public action, including petitions and legislative outreach, to protect NDT access and affordability.

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Q&A Video from 2022: Understand the history of the FDA's NDT Actions

This 20-minute Q&A with patient advocate Mary Shomon was conducted in early November of 2022, and provides an overview of the background on the regulatory developments on natural desiccated thyroid.

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