How long does it take for Armour Thyroid to work?

Armour Thyroid (desiccated thyroid extract) contains both T3 (triiodothyronine) and T4 (thyroxine) hormones derived from porcine thyroid glands. It replaces low thyroid hormone levels in conditions such as Hashimoto’s thyroiditis, goiters, nodules, or thyroid cancer.

After your first dose, thyroid hormone levels begin to rise, but it can take up to 6 weeks before you experience full relief of symptoms such as fatigue, cold intolerance, weight gain, and slowed heart rate. Your healthcare provider will check your T4 and TSH levels every 2–3 weeks and adjust your dose until your blood tests fall within the normal range. Armour Thyroid is usually taken long term and should not be stopped without consulting your provider.

Possible side effects

  • Increased heart rate or palpitations
  • Chest pain
  • Tremors
  • Muscle weakness
  • Excessive sweating
  • Anxiety or nervousness
  • Diarrhea
  • Insomnia
  • Rare serious reactions: allergic response, cardiac complications

Typical dosing

  • Available in eight strengths (¼ grain to 5 grains; each grain = 38 mcg T4 + 9 mcg T3)
  • Usual adult starting dose: 30 mg once daily on an empty stomach
  • Dose may be increased up to 120 mg daily based on lab results
  • Lower starting doses for those with heart disease or severe hypothyroidism
  • Children’s doses are weight‑ and age‑based
  • If a dose is missed, take as soon as remembered unless the next dose is due soon—do not double up

Levothyroxine vs. Armour Thyroid

Levothyroxine (Synthroid, Levoxyl) is a synthetic T4-only hormone with consistent potency and is first‑line for most patients. Armour Thyroid delivers both T3 and T4 but may vary between batches. Your provider can advise which formulation best meets your needs.

Drug interactions

  • Cholestyramine or colestipol (cholesterol drugs)
  • Estrogen‑containing medications
  • Warfarin (blood thinner)
  • Iodine‑containing drugs
  • Calcium or iron supplements
  • Certain steroids (e.g., prednisone)
  • Amphetamines (e.g., dextroamphetamine)
  • Antidepressants, anticonvulsants, HIV and antifungal agents
  • Digoxin (heart medication)
  • Insulin and oral diabetes drugs

Use for weight loss

Armour Thyroid is not approved for weight loss in people with normal thyroid function. Taking excessive doses for this purpose can lead to serious, life‑threatening complications.

Hair loss

Temporary hair thinning may occur during the first few months of treatment as hormone levels normalize and hair follicles adjust. This typically resolves within 4–8 weeks.

Sources

  • Armour Thyroid Package Insert. AbbVie, Inc., 2024.
  • Hypothyroidism (Underactive Thyroid). National Institute of Diabetes and Digestive and Kidney Diseases.
  • Toloza FJK et al. Patient Experiences with Desiccated Thyroid Extract. Medicina (Kaunas). 2020;56(4):161.
  • Medscape: Thyroid Desiccated Extracts.