FDA Bans All Glandular Thyroid Preparations (Armour, NP Thyroid, Thyroid)

In August 2025, the FDA officially designated all glandular thyroid preparations—including Armour Thyroid, NP Thyroid, and other desiccated thyroid extract (DTE) medications—as “unsafe.” This decision has significant implications for patients currently using these medications.

Although Armour Thyroid has been in use since the early 1900s, the FDA reports receiving adverse event notifications over the years. One of the agency’s concerns is the variability in the hormone content of these products. Because desiccated thyroid is derived from pig thyroid glands, the actual amounts of T4 (thyroxine) and T3 (triiodothyronine) can vary between batches. According to the FDA, this inconsistency may pose risks to patients—despite the fact that the human thyroid naturally varies its hormone production based on the body's needs.

The FDA now recommends that patients transition to synthetic levothyroxine (brand names include Synthroid and Levoxyl). Levothyroxine is a bioidentical form of T4, the inactive thyroid hormone. Once in the body, T4 must be converted to T3—the active form that regulates metabolism and energy use.

In contrast, desiccated thyroid medications like Armour Thyroid contain not only T4 and T3, but also T1, T2, and calcitonin—components that may have additional physiological roles. Some patients do not efficiently convert T4 into T3. For these individuals, switching solely to levothyroxine may result in symptoms of hypothyroidism, such as:

  • Fatigue

  • Brain fog

  • Hair thinning or hair loss

  • Constipation

  • Depression

  • Weight gain

  • Cold intolerance (e.g., cold hands and feet)

What Should You Do Next?

If you are currently taking a desiccated thyroid extract, we recommend scheduling an appointment with one of our providers to discuss your treatment options. Depending on your specific needs, we may consider:

  • Nutritional and lifestyle support to enhance T4-to-T3 conversion

  • Adding liothyronine (synthetic T3) to your levothyroxine prescription for a more balanced approach

For more information, you can visit the FDA’s official announcement here:
👉 FDA Actions on Unapproved Thyroid Medications

Kristen PlunkettNaturopathic Medical Clinic