Natural Desiccated Thyroid Medications: Will They Disappear?

FDA Deadline Set

If you take a natural desiccated thyroid (NDT) medication like Armour®, NP Thyroid®, or Nature-Throid®, there’s some important news from the FDA that’s making waves in the thyroid community.

On August 6, 2025, the FDA announced it will be taking action against unapproved, animal-derived thyroid medications. The FDA has announced up to a 12-month transition period. After that, enforcement actions may begin if a biologics license hasn’t been secured. Manufacturers will have to either get them approved or stop selling them in the United States.

Why the FDA is Doing This

The FDA has reclassified NDT as a biological product. A biologic is a drug or vaccine made from a living organism (which includes proteins, sugars, DNA, cells or living tissue; the source may be human, animal or a microorganism like a bacteria or virus). That means; to remain on the market, these drugs must go through the Biologics License Application (BLA) process, the same rigorous review used for other biologic drugs (like Humira® and Embrel®).

According to the FDA, the main concerns with NDT are:

• Potency consistency: Different tablets from the same batch may contain varying amounts of T4 and T3. Too much can cause hyperthyroid symptoms; too little can leave patients under-treated with hypothyroid symptoms.

• Other thyroid components: Unlike synthetic medications, NDT naturally contains additional thyroid hormones like T0, T1 and T2, as well as calcitonin. T₀ and T₁ are considered inactive byproducts. T₂ may influence metabolism based on animal studies, but its role in humans is not well understood. Calcitonin is active - it helps regulate calcium and bone metabolism, but the small amounts in NDT are unlikely to have a major clinical effect.

• Potential impurities: Potential impurities: Because NDT is made from animal thyroid glands (usually pigs), there’s a small but real risk of microbial contamination, environmental toxin residues (including heavy metals), or non-hormonal proteins that could trigger immune reactions, especially with people who have autoimmune conditions. Porcine tissues naturally carry retroviral genetic material, but manufacturing steps greatly reduce any risk of active infection.

• Lack of modern approval: NDT has been prescribed for decades, long before the FDA required formal proof of safety (1938) and efficacy (1962). Because it was already in common use for hypothyroidism, it was “grandfathered” onto the market without going through the current FDA approval process. Its continued use was based on physician experience and historical effectiveness rather than modern clinical trial data.

Some patients also notice differences from one refill to the next, even without a dose change. When I was at my most sensitive, I found that certain batches of Armour® seemed to work well, while others left me feeling run down within a week. This is exactly the type of variability the FDA is citing as a safety concern.

What This Means Right Now

• NDT is still available. If you currently take Armour®, NP Thyroid®, or similar, you can continue filling your prescription.

• No immediate recalls. The FDA is giving patients and providers time to transition, if needed.

• Compounded NDT is already off the table. Because NDT is now regulated as a biologic, compounding pharmacies can no longer legally make it from animal thyroid powder, even with a prescription. They can, however, still compound synthetic T3 and T4.

What This Could Mean for the Future

Some people have raised concerns that the reclassification of NDT as a biologic could eventually drive prices up. If a company does go through the BLA process and gets FDA approval, they would have 12 years of market exclusivity before another manufacturer could sell a competing biosimilar (a “generic” version of a biologic, but not an exact copy and slower/more expensive to develop).

Without competition (and with compounded NDT already off the market) prices could increase, especially if only one manufacturer gets approval.

What About Over the Counter “Thyroid Support” or Glandular Supplements?

You’ll also see OTC supplements labeled as “thyroid support” that contain bovine or porcine glandular extracts and are supposed to be hormone-free. In practice, though, that’s not always true.

In one study, 9 of 10 tested thyroid-support supplements contained T3 and 5 had T4, even when the label didn’t list those hormones. A different study on adrenal-support capsules found T3 in every product tested.

Because supplements aren’t regulated like prescription meds, amounts can be inconsistent. Unknowingly ingesting T3 or T4 can amplify thyroid activity, disrupt labs, lead to hyperthyroid symptoms, or even cause arrhythmias or bone loss in some people.

While these OTC glandular supplements aren’t part of the FDA’s 2029 deadline, they do carry their own risks (which is worth keeping in mind if you use them or are considering switching to them).

Updated: The Deadline

On August 6, 2025, the FDA announced that manufacturers, importers, and distributors of unapproved, animal-derived thyroid medications have up to 12 months from the notice date to either:

• Submit a Biologics License Application (BLA) and receive FDA approval, proving the drug is safe, effective, and consistently manufactured, or

• Stop selling the product in the U.S. entirely.

This replaces the earlier “2029” date. FDA approval is not guaranteed. The process is expensive, can take years, and requires strict quality control. If approval isn’t granted, NDT would be removed from U.S. pharmacies and no longer available by prescription after the transition period ends.

Your Options (If You’re on NDT)

If you like the balance of T4 and T3 you get from NDT but want to plan ahead, here are the main alternatives:

• Synthetic T4 (levothyroxine) alone: Brands like Synthroid®, Levoxyl®, and Tirosint®.

• Synthetic T3 (liothyronine) alone: Brand name Cytomel® or generic liothyronine.

• Synthetic T4/T3 combination therapy: To recreate the balance of T4 & T3 in NDT, you'll need to combine synthetic levothyroxine and liothyronine. This can be prescribed in standard doses or compounded to avoid fillers (unlike NDT, synthetic hormones can still be compounded).

  
  

If You’re Sensitive to Fillers

Many people tolerate synthetic T4 and T3 well, but others react to the dyes, binders, or other inactive ingredients. Your best options here:

• Tirosint®, a liquid gelcap or liquid formulation with no fillers, dyes, gluten, or lactose. It contains only T4 (no T3), so this is a pharmaceutical T4 option without common fillers.

• Compounded synthetic T4 and/or T3 can be made in hypoallergenic formulations through compounding pharmacies. This is still legal because they’re made from synthetic, FDA-approved raw materials, not animal thyroid tissue.

  
  

How Changing Medications Can Affect Labs and Symptoms

If you switch from NDT to synthetic thyroid hormones, your labs will likely look different, and so might your symptoms (at least at first).

• T4-only medications will generally raise Free T4 levels more than NDT does.

• Without the immediate T3 that NDT provides, you may notice slower symptom improvement at first (T4 takes time to convert, and many things can block conversion).

• Combination synthetic therapy can be adjusted more precisely than NDT, but it may require trial and error to find your optimal ratio.

Tip: After any medication change, it’s best to recheck thyroid labs in 6–8 weeks and track symptoms carefully.

TL;DR

Natural desiccated thyroid isn’t banned today, but it’s on a clear path toward possible removal from the U.S. market if manufacturers can’t secure FDA approval by 2029. That means now is the time to:

• Talk with your doctor about your options.

• Explore whether you might tolerate synthetic alternatives, especially compounded or filler-free versions if you’re sensitive.

• Have a plan in place so you’re not scrambling if NDT is removed from pharmacies.

I know this decision is going to spark a lot of “Big Pharma” commentary, which is completely valid. There’s an uncomfortable reality here: natural medications that have been used for over a century are now being forced to either undergo an extremely expensive approval process or be removed from the market. That creates some cognitive dissonance in movements that claim to champion natural health and medical freedom. In my view, this shows that when there’s money to be made, even some of the loudest voices in those spaces still side with the pharmaceutical industry, and it's really disappointing.

Ready to take charge of your thyroid health now?

Even if you stay on NDT for the time being, this is the perfect moment to make sure your own hormone production and conversion are working as well as they can. My free Thyroid Lab Guide helps you understand your labs and track your results over time.

My Back to Balance program walks you step-by-step through optimizing thyroid function, supporting conversion, and addressing root causes naturally. That way, if medication changes become necessary, your body is in the best position possible to adapt, and you’ll already have a solid plan and stable health in place. Back to balance is moving to a brand-new platform and I'm giving the whole course an overhaul with new sections and updated videos. I'll be looking for a few beta testers soon, so if you want first dibs on the limited spots to try out the new platform at am amazing discount, jump on the VIP list.

If you like what you’re learning here, you’ll love the conversations happening inside my free Facebook group, Find Your Balance. Come join us!

Disclaimer: I do not diagnose, treat, prevent, or cure any disease or condition. Nothing I share with my clients is intended to substitute for the advice, treatment or diagnosis of a qualified licensed physician. I may not make any medical diagnoses or claim, nor substitute for your personal physician’s care. It is my role to partner with you to provide ongoing support and accountability in an opt-in model of self-care and any changes should be done under the supervision of a licensed physician.