Liothyronine (T3)
Synthetic T3. Short half-life, so it is often split across the day rather than taken once.
Medications & hormones
Research records
Historical source snapshot. Not freshly verified, not a recommendation. Study findings, community accounts and app defaults are not interchangeable.
Publication suitability · 2026-10-15: Historical reference only; not a clinical verification. Clinical, regulatory, efficacy, safety and dose claims are not independently established by this review.
Liothyronine (T3)
Synthetic T3. Short half-life, so it is often split across the day rather than taken once.
Evidence category: Regulator / guideline. This describes the source category, not approval or certainty.
Regulatory statement in source: FDA-approved.
Liothyronine is synthetic T3 with an FDA-approved label (Cytomel). It is approved as replacement in hypothyroidism, as an adjunct in managing well-differentiated thyroid cancer by suppressing TSH, and as a diagnostic agent in thyroid suppression tests. The label carries a boxed warning that thyroid hormones must not be used for obesity or weight loss, and that amounts beyond hormonal needs can cause serious toxicity.
Benefits reported in the imported source
- Replacement therapy in hypothyroidism.
- An adjunct in well-differentiated thyroid cancer, by suppressing TSH.
- A diagnostic agent in thyroid suppression tests.
Risks and limits
- A boxed warning states thyroid hormones must not be used for obesity or weight loss.
- The label warns that amounts beyond hormonal needs can cause serious toxicity.
Source bottom line: Liothyronine is FDA-approved thyroid hormone replacement, with a boxed warning against use for weight loss.
Uncertainty: Reference information only. Not medical advice.
Study protocols — reports, not instructions
Adults with hypothyroidism, per the US label
- Reported regimen
- 25 mcg orally once daily to start, increased by 25 mcg daily every 1 or 2 weeks; usual maintenance 25 mcg to 75 mcg once daily
- Duration
- Ongoing, per the label
- Reported outcome
- Approved as replacement therapy in hypothyroidism; the label's boxed warning states thyroid hormones must not be used for obesity or weight loss.
- Source
- Liothyronine sodium tablets FDA prescribing information
Claim provenance
evidence.json#/catalog:hormone:liothyronine/protocols/0
People with well-differentiated thyroid cancer needing TSH suppression, per the US label
- Reported regimen
- Dose targeted to keep TSH within the desired therapeutic range, which the label says may require higher doses
- Duration
- Ongoing, per the label
- Reported outcome
- Approved as an adjunct to surgery and radioiodine in managing well-differentiated thyroid cancer.
- Source
- Liothyronine sodium tablets FDA prescribing information
Claim provenance
evidence.json#/catalog:hormone:liothyronine/protocols/1
People undergoing a thyroid suppression test, per the US label
- Reported regimen
- 75 mcg to 100 mcg daily, with radioactive iodine uptake measured before and after the administration
- Duration
- 7 days
- Reported outcome
- Approved as a diagnostic agent in thyroid suppression tests.
- Source
- Liothyronine sodium tablets FDA prescribing information
Claim provenance
evidence.json#/catalog:hormone:liothyronine/protocols/2
Community and practice descriptions
Accounts of a practice are not evidence of safety or effectiveness. Words such as “standard”, “safe” or “recommended” describe the source account, not verified consensus or this wiki’s advice. Commercial and self-published citations are retained for traceability, not vendor endorsement or independent clinical corroboration.
Unverified imported account — Liothyronine (T3) Cycle — Dosage, Contest Prep & GH Stack
An imported authored paraphrase, not a quotation or a recommended protocol.
Review: unverified historical account. The imported wording is preserved for attribution; its full clinical, dosing, efficacy or consensus claims have not been independently established. Unvalidated source account; no validated human dosing population or animal-to-human equivalence is inferred.
Imported wording: A performance optimization guide documents that community members using T3 for fat loss typically begin at 25-50 mcg once daily, with increases of 12.5 mcg every 5-7 days for those on intermediate protocols.
Liothyronine (T3) Cycle — Dosage, Contest Prep & GH Stack
Unverified imported account — T3 split dose experiences | Thyroid UK HealthUnlocked
An imported authored paraphrase, not a quotation or a recommended protocol.
Review: unverified historical account. The imported wording is preserved for attribution; its full clinical, dosing, efficacy or consensus claims have not been independently established. Unvalidated source account; no validated human dosing population or animal-to-human equivalence is inferred.
Imported wording: Users on thyroid patient forums describe splitting their T3 dose to manage absorption peaks, with examples including 10 mcg at 5am, 7.5 mcg at 1pm, and 2.5 mcg at 4pm to smooth the effect over the day.
Pharmacokinetic context
Historical half-life estimate: 60 hours. FDA label, Cytomel: biological half-life about 2 1/2 days Population/route context and estimates may differ. This is not a schedule or a verified human dosing rule.
Source references
- CYTOMEL (liothyronine sodium) FDA Label
- Liothyronine sodium tablets FDA prescribing information
- DailyMed: liothyronine
Snapshot provenance
Source ID: catalog:hormone:liothyronine. Commit: adc7684614f9439b41d91a3312b62e7982c7e20e. Review state: historical-not-reverified. Authored links are retained separately from the canonical evidence links in the public data. App templates/defaults and rejected drafts are archived, not deployed.
Related entries and components
None listed.