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Does np thyroid work as well as erfa thyroid?

Both NP Thyroid and ERFA Thyroid are natural desiccated thyroid (NDT) products derived from pig thyroid glands, containing T4 and T3 in the same proportions as the human thyroid. They were “grandfathered” by the FDA as safe and effective before modern synthetic thyroid hormones existed.

Formulation and efficacy

  • Active hormones (T4 and T3) are identical in NP Thyroid, ERFA Thyroid, Armour Thyroid, Nature‑Throid, and WP Thyroid.
  • Clinical studies show no significant difference in thyroid hormone levels or symptom relief when dosed appropriately.
  • Differences in inactive fillers can affect absorption and tolerance.

Inactive ingredients (excipients)

Excipients bind the tablet, ensure consistent dosing, and aid absorption, but can also cause variability between brands and allergic reactions. Always review ingredient lists and discuss any concerns with your provider.

Side effects of NP Thyroid and ERFA Thyroid

  • Common (due to excessive thyroid hormone): palpitations, chest pain, tremors, hair loss, muscle weakness, sweating, weight changes, anxiety, diarrhea
  • Serious (rare): cardiac arrhythmias, adrenal insufficiency (fatigue, dizziness), hyperglycemia, life‑threatening allergies (hives, swelling, breathing difficulty)

Manufacturers

  • NP Thyroid: Acella Pharmaceuticals
  • ERFA Thyroid: Searchlight Pharma (ERFA Canada Inc.)

Switching between brands

Once stabilized on one NDT brand, do not switch without close monitoring. Changing excipients can alter absorption and hormone levels, potentially worsening symptoms or side effects.

Sources

  • Heald AH, et al. Natural desiccated thyroid for hypothyroidism? Front Endocrinol. 2024;14:1309159.
  • Ettleson MD, Bianco AC. Is T4 enough for everyone? J Clin Endocrinol Metab. 2020;105(9):e3090‑e3104.
  • Hoang TD, et al. Desiccated thyroid vs levothyroxine: J Clin Endocrinol Metab. 2013;98(5):1982‑90.
  • NP Thyroid Prescribing Information. Acella Pharmaceuticals. Last updated 10/2019.
  • ERFA Thyroid. Desiccated Thyroid C.S.D. HRES. Last update 5/2020.