Is Armour Thyroid FDA Approved?

Armour Thyroid is a desiccated thyroid extract (DTE) used to treat hypothyroidism and to suppress thyroid‑stimulating hormone (TSH) in certain thyroid disorders. Although it has been available by prescription for decades, it predates the modern FDA approval process and was “grandfathered” in—so it never underwent the clinical trials and formal review required of newer medications.

Because DTE products like Armour Thyroid were on the market before FDA regulations were established, they remain available without an official FDA approval. No formal evaluation of their safety, potency consistency, or efficacy has been performed by the FDA.

Role of your thyroid gland

Your thyroid sits in the front of your neck and produces hormones (T3 and T4) that regulate metabolism, energy use, body temperature, heart rate and many other processes. When the gland makes too little hormone (hypothyroidism), you can experience fatigue, weight gain, cold sensitivity, dry skin, hair loss, constipation, slowed heart rate and other symptoms. When it makes too much (hyperthyroidism), symptoms can include weight loss, rapid heartbeat, anxiety, tremors and insomnia.

Negative effects of Armour Thyroid

Many side effects mirror hyperthyroidism and arise if dosing is too high:

  • Increased heart rate or palpitations
  • Chest pain
  • Tremors
  • Muscle weakness
  • Excessive sweating
  • Anxiety or nervousness
  • Diarrhea
  • Insomnia
  • Weight changes
  • Hair loss (often early in therapy)

Rare but serious reactions include:

  • Cardiac complications in those with existing heart disease
  • Adrenal insufficiency symptoms (fatigue, dizziness, abdominal pain)
  • Elevated blood sugar requiring adjustment of diabetes medications
  • Severe allergic reactions (hives, throat swelling, difficulty breathing)

Additional risks with desiccated thyroid extracts

  • Batch‑to‑batch variability in hormone content can lead to under‑ or overdosing
  • Pig gland ratio of T3 to T4 differs from human physiology, risking thyrotoxicosis
  • Potential contamination from animal‑derived material processing

Who should avoid Armour Thyroid?

  • Those with untreated adrenal gland disorders
  • Untreated thyrotoxicosis or severe hyperthyroidism
  • Allergy to any component of the product
  • Patients needing tightly controlled, consistent dosing (e.g., certain cardiac conditions)

FDA‑approved thyroid hormone replacements

Synthetic preparations have standardized potency and have undergone FDA review:

  • Levothyroxine (T4 only) – brand names Synthroid, Levoxyl, Tirosint, Unithroid
  • Liothyronine (T3 only) – brand name Cytomel

Sources

  • U.S. Food and Drug Administration: Older Therapies Aren’t Necessarily Better for Thyroid Hormone Replacement
  • Armour Thyroid Package Insert, AbbVie, Inc.
  • National Institute of Diabetes and Digestive and Kidney Diseases: Hypothyroidism Overview
  • Medscape: Thyroid Desiccated Extracts