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What is in erfa thyroid?

ERFA Thyroid is a natural desiccated thyroid (NDT) extract made from dried pig (porcine) thyroid glands. It contains a fixed ratio of:

  • Thyroxine (T4)
  • Triiodothyronine (T3)

NDT products like ERFA Thyroid have more T3 relative to T4 than the human thyroid produces. This differs from synthetic options:

  • Levothyroxine (Synthroid): T4‑only
  • Liothyronine (Cytomel): T3‑only

How does ERFA Thyroid work?

In hypothyroidism, your thyroid fails to produce enough T4 and T3, causing symptoms like fatigue, weight gain, dry skin, and cold intolerance. ERFA Thyroid replaces both hormones, restoring normal levels. Dosing is adjusted based on:

  • Clinical response
  • TSH and T4 (and sometimes T3) blood tests

Side effects of ERFA Thyroid

Excess thyroid hormone (overdose) leads to hyperthyroid-like symptoms:

  • Headache, nausea, vomiting
  • Irregular heartbeat, chest pain, palpitations
  • Tremors, muscle weakness, insomnia
  • Anxiety, irritability
  • Diarrhea, weight loss
  • Skin rash or hives, irregular menstrual periods

Rare serious effects:

  • Allergic reaction (hives, swelling, difficulty breathing)
  • Heart attack or heart failure signs (chest pain, swelling, shortness of breath)

ERFA Thyroid vs. Armour Thyroid

Both are porcine NDTs containing T3 and T4. Main differences:

  • Brand origin (ERFA: Canada; Armour: USA)
  • Inactive fillers/excipients
  • Slight hormone ratio variations

Do not switch brands without medical supervision.

Natural vs. Synthetic thyroid hormones

  • Natural (ERFA Thyroid): Contains both T4 and T3 in their bioidentical forms.
  • Synthetic T4 (Synthroid): Requires peripheral conversion to T3.
  • Synthetic T3 (Cytomel): Directly provides T3.

Synthetic products have consistent hormone content; NDT potency may vary and have occasional recalls, making levothyroxine the preferred first‑line therapy.

Sources

  • Thyroid desiccated (Rx). Medscape. Accessed Feb. 11, 2025.
  • Armour Thyroid – porcine thyroid tablet. DailyMed. Accessed Feb. 11, 2025.
  • ERFA Thyroid. HRES. Last update 5/2020. Accessed Feb. 11, 2025.