Levothyroxine vs. Nature-Throid

See how Levothyroxine and Nature-Throid compare on approved uses, dosing, side effects, and cost.

Key Takeaways

  • Levothyroxine is FDA-approved and contains only T4, while Nature-Throid is a non-FDA-approved desiccated thyroid product containing both T4 and T3.

  • Both drugs treat hypothyroidism, but only levothyroxine has gone through formal FDA review for safety, purity, and consistent potency batch to batch.

  • Nature-Throid has faced repeated supply shortages, including a 2020 recall for subpotent tablets, making levothyroxine the more reliably available option.

Levothyroxine vs. Nature-Throid Drug Summary

Levothyroxine

Levothyroxine is a synthetic form of thyroid hormone (T4) used to treat hypothyroidism and to suppress TSH after thyroid cancer treatment. It's taken as a once-daily tablet, capsule, or injection, with the dose adjusted based on regular TSH and T4 blood tests.

Nature-Throid

Nature-Throid is a desiccated thyroid hormone made from porcine thyroid glands, containing both T4 and T3 along with trace amounts of other thyroid compounds. It's taken as a once-daily tablet to treat hypothyroidism and suppress TSH in certain thyroid conditions, though it has never received formal FDA approval.

Levothyroxine vs. Nature-Throid Side Effects

Levothyroxine

Most common
Tremors (dose-dependent)
Palpitations (dose-dependent)
Headache (dose-dependent)
Nervousness (dose-dependent)

Nature-Throid

Most common
Tremors (dose-dependent)
Palpitations (dose-dependent)
Hair loss (dose-dependent)
Weight loss (dose-dependent)

Levothyroxine vs. Nature-Throid Dosage

Levothyroxine

Dosage
Dosage Table
STAGE DOSE WHEN
Starting dose 12.5-25 mcg once daily Weeks 1-6
Maximum dose 1.6 mcg/kg once daily If needed
Dose changes 2 increases As tolerated

Nature-Throid

Dosage
Dosage Table
STAGE DOSE WHEN
Starting dose 15 mg (1/4 grain) daily At the start
Maximum dose 60-120 mg (1-2 grain) daily If needed
Dose changes 2 increases As tolerated

Levothyroxine vs. Nature-Throid Indications

Levothyroxine

Levothyroxine replaces the thyroid hormone the body can't make enough of on its own, treating hypothyroidism from any cause affecting the thyroid, pituitary, or hypothalamus. It's also used to suppress TSH production after thyroid cancer treatment. It carries a boxed warning against use for weight loss, since doses beyond hormonal needs can cause serious harm.

  • Primary, secondary, or tertiary hypothyroidism

  • TSH suppression in thyroid cancer management

  • Not approved for weight loss (boxed warning)

Nature-Throid

Nature-Throid treats hypothyroidism from nearly any cause except the transient thyroiditis recovery phase, and it's used to suppress TSH in conditions like goiters, thyroid nodules, and Hashimoto's disease. It's also used as an adjunct in thyroid cancer management and as a diagnostic agent in thyroid suppression testing. Like levothyroxine, it's not approved for weight loss and can cause serious toxicity at doses beyond what the body needs.

  • Hypothyroidism of any cause (except thyroiditis recovery)

  • TSH suppression in goiters, nodules, Hashimoto's

  • Adjunct in thyroid cancer management

Levothyroxine vs. Nature-Throid Pros and Cons

Levothyroxine

Levothyroxine's decades of FDA oversight mean consistent potency from batch to batch, which matters for a drug with a narrow therapeutic index. It's inexpensive as a generic and rarely affected by supply disruptions.

Pros

  • FDA-approved with decades of established safety data

  • Widely available and rarely affected by supply shortages

  • Contains only T4, making dose adjustments more predictable

Cons

  • Some patients feel T4-only therapy doesn't fully relieve symptoms

  • Requires the body to convert T4 to active T3 on its own

  • Doesn't supply T3 or trace thyroid compounds directly

Nature-Throid

Nature-Throid appeals to patients who feel that T4-only therapy doesn't fully resolve their symptoms, since it supplies T4 and T3 directly rather than relying on the body to convert one to the other. But because it was never subject to a modern FDA approval process, its potency consistency and availability have been less predictable.

Pros

  • Supplies both T4 and T3 directly, without relying on conversion

  • Some patients report symptom improvement beyond T4-only therapy

  • Long history of use dating back to the 1930s

Cons

  • Never received formal FDA approval; potency review is less rigorous

  • History of shortages, including a 2020 recall for subpotent tablets

  • Fixed T4:T3 ratio may not match individual hormone needs

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