FDA Ban on Popular Natural Thyroid Drug Sparks Controversy

The Federal Drug Administration (FDA) sparked controversy earlier this month after it announced a ban on a popular natural thyroid drug used by millions of Americans suffering from hypothyroidism.

Outrage over the recent FDA action also hinged on the apparent conflict between the Trump administration’s promises to “Make America Healthy Again” (MAHA): namely, a reduced reliance on synthetic chemicals, support for integrative medicine, scrutiny on conventional medicine, and expanded access to natural products.

Approximately 30 million Americans over the age of 18 have hypothyroidism. Of that population, an estimated 22 million patients use synthetic thyroid medication. An estimated 1.5 million Americans rely on natural desiccated thyroid (NDT), the thyroid medicine derived from animal thyroid glands which originated in the 1890s and was grandfathered in by the FDA. Many of these Americans taking NDT have contraindications to synthetic thyroid medications and cannot take them.

Accordingly, the FDA action would have these 1.5 million Americans compromise their health and deprive them of the MAHA promise.

The FDA advised these Americans they would have until August 2026 to “safely” transition to an FDA-approved thyroid medication, which only includes synthetic thyroid drugs.

Available data within the FDA Adverse Event Reporting System (FAERS) reveals that all of the top NDT drugs combined have a fraction of the adverse reports compared to those accrued by just one of the leading synthetic thyroid drug brands.

Levothyroxine, the generic synthetic form of the thyroid hormone thyroxine (T4), has nearly 20,000 adverse events reported since its FDA approval about 20 years ago. Synthroid, the leading brand name for levothyroxine, has over 25,700 adverse events reported since its FDA approval about 20 years ago.

By comparison, the generic version and top three NDT drugs — Armour Thyroid, Nature-Throid, and NP Thyroid — have less than 3,000 adverse events reported over the course of 50 years and only about 2,600 adverse events reported since 20 years ago.

The FDA did admit in their notice letters to NDT manufacturers, importers, and distributors that they didn’t have exact proof of their safety and efficacy claims against NDT.

“FDA is unaware of any studies demonstrating the safety and effectiveness of ADT products, meaning the benefits and risks of treatment with ADT products have not been adequately assessed,” read the FDA letter.

Given these facts, leading medical professionals and NDT patients are questioning who stands to benefit from this FDA action.

Despite the popularity of this drug, few elected officials have spoken up for their constituents. Among them was Congressman Abe Hamadeh.

Hamadeh issued a letter requesting the FDA answer certain questions about the restriction on NDTs — specifically, the evidence supporting their action and whether the FDA had analyzed how their action would impact patients reliant on NDTs.

“Arizona’s 8th Congressional District has a significant veteran and senior population who depend on consistent access to thyroid medications. Many of these patients have found desiccated thyroid medications to be more effective than synthetic alternatives for managing their thyroid conditions. Any disruption to their treatment regimens could have serious health consequences and undermine the doctor-patient relationship.”

🇺🇸NEW🇺🇸

Congressman Abe Hamadeh Questions FDA About Availability of Popular Thyroid Medications

Read Press Release⤵️https://t.co/51t4D0JMQN

— Office of Congressman Abe Hamadeh (@RepAbeHamadeh) August 18, 2025

It’s not as simple for NDT manufacturers to obtain regular FDA approval, either. The FDA action announced their desire to have NDT reclassified entirely. This will likely prove to be a costly burden to patients.

The FDA ordered NDT manufacturers to obtain approval for the drug under a “biologic” classification. The FDA regards drugs designated as biologics as “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.”

Contrary to its historic understanding of NDT, the FDA recently decided that NDT’s derivation from pig thyroid glands and the minute presence of the protein thyroglobulin in the drug qualifies it as a biologic. The protein is not an active ingredient within NDT.

Reclassifying NDT as a biologic would mean a ban on compounded NDT and prevent foreign importation of NDT. This would result in an extreme rise in costs for the drug. The most popular biologics on the market currently cost thousands of dollars per month on average: Humira (whose manufacturer AbbVie, also makes one of the leading NDTs, Armour Thyroid) costs $7,500 a month; Remicade costs $2,000 to $7,000 per month depending on dose frequency; Enbrel costs $8,000 per month; and Skyrizi costs $10,000 per month.

The current formulations of NDT as compounded drugs allows them to be more cost-friendly on average: Armour Thyroid costs $60 per month, and NP Thyroid costs $30 to $60 per month.

At present, no NDT drugs are approved as biologics and no manufacturers have filed an application with the FDA. It can take years for these studies and approvals to emerge, well beyond the August 2026 deadline set forth by the FDA.

In apparent response to social media backlash over the looming ban, FDA Commissioner Marty Makary issued this statement:

“FDA is committed to pursuing the first-ever approval of desiccated thyroid extract, pending results of the ongoing clinical trials. In the meantime, we will ensure access for all Americans.”

FDA is committed to pursuing the first-ever approval of desiccated thyroid extract, pending results of the ongoing clinical trials. In the mean time, we will ensure access for all Americans.

— Dr. Marty Makary (@DrMakaryFDA) August 14, 2025

However, Department of Health and Human Services spokesman Andrew Nixon told NBC News after Makary’s statement that the FDA would still take action against manufacturers making NDT and would require patients to transition to FDA-approved thyroid drugs. Currently, the only ones that have approval are the synthetic kind.

“FDA is not taking immediate action against manufacturers who make unapproved animal-derived thyroid medication to give patients time to transition to an FDA-approved medication to treat their hypothyroidism,” said Nixon.

Makary and Nixon didn’t offer a concrete timeline for FDA approvals and transitions. The only official timeline is the one offered in the initial FDA action, which is August 2026.

Both Makary and Nixon referenced “clinical trials” in their statements. However, the only publicly known trials occurred back in 2012 and 2021: the former a Walter Reed National Military Medical Center trial with an “unknown” completion status, and the latter a completed trial by Allergan, the maker of Armour Thyroid.

However, BLA submission takes anywhere from several years to a decade, and about another year for FDA review for approval.

The NDT ban was one of the first actions undertaken by the newly appointed director of the Center for Drug Evaluation and Research (CDER), George Tidmarsh.

“The new FDA needs to remove harmful, useless drugs from the market,” wrote Tidmarsh on LinkedIn approximately seven months before his CDER appointment. “Let’s start with desiccated thyroid extract. An unapproved, crude pig tissue extract that is proven worse than synthetic thyroid hormone and harmful. Working with the new FDA to remove it permanently from the market.”

Tidmarsh is not an endocrinologist; his background is in oncology and neonatology. There also doesn’t appear to be any crossover into endocrinology with the seven FDA-approved drugs he helped to develop, nor the seven companies he founded or led.

Given the endocrinology void in Dr. Tidmarsh’s background, more questions than answers remain for his pointed interest in removing a specific thyroid drug from the market — especially one derived from a natural source and an 130-year history of uncomplicated use, something that should be right up MAHA alley.