T3 (Cytomel/Liothyronine) — Dosing, Cycles, Half-Life & Side Effects

Quick Facts

Typical Dosing Ranges

Common dose range: 12.5-50mcg/day

Cycle length: 4-8 weeks with taper

Time to steady state: ~5 days

Dose ranges are compiled from published pharmacokinetic studies and community-reported usage. Where a value is community-reported rather than clinically studied, this page and its structured data flag it. Lower end of any range is always the safer starting point.

Stacking Considerations

• No structural stacking blockers. Standard harm-reduction rules apply: minimize total androgen load, minimize oral exposure, and monitor bloodwork.

PCT Requirements

• Depot clearance estimate: ~5 days post-last-dose before SERM start (5 × apparent depot half-life of 24h).
• Never stack two SERMs. Extend a single SERM (tamoxifen OR enclomiphene/clomiphene) rather than combining.
• Use the cycle planner to generate a full protocol based on your complete stack, not this compound alone.

Side Effect Profile

• Thyroid suppression
• Muscle catabolism
• Cardiac strain
• Requires careful dosing
• Suppresses natural thyroid function
• Can cause cardiac arrhythmias at high doses
• May cause muscle loss if not combined with AAS
• Requires gradual tapering to restore thyroid function

Known Interactions

• Trenbolone Acetate + T3 (Cytomel/Liothyronine)

  moderate — cardiovascular

  T3 increases metabolism and heart rate while trenbolone affects cardiovascular health.

  Recommendation: Use lowest effective doses. Monitor vitals closely.

  Monitor: Heart rate, Blood pressure, TSH

Related compounds

• T4 (Levothyroxine/Synthroid)

  Thyroid Hormone · t½ 7 days

• Albuterol

  Beta-2 Agonist · t½ 4-6 hours

• Clenbuterol

  Beta-2 Agonist · t½ ~35 hours in healthy adult humans (Yamamoto et al. 1985, J Pharmacobiodyn, PMID: 4045696, oral 20-80 mcg). Earlier 36-48h estimates appear to have conflated with non-human data (rabbits ~9h, rats ~30h in the same study).

• DNP (2,4-Dinitrophenol)

  Mitochondrial Uncoupler · t½ 36 hours

Monitoring (Bloodwork & Vitals)

• Comprehensive metabolic panel (baseline, mid-cycle, post-cycle)
• Lipid panel (total cholesterol, HDL, LDL, triglycerides)
• CBC (hemoglobin, hematocrit — watch for erythrocytosis)
• Sex-hormone panel (Total T, Free T, Estradiol sensitive, SHBG, LH, FSH)
• Blood pressure (weekly self-check; flag systolic >140 or diastolic >90)

Baseline bloodwork is recommended before any cycle. Discontinue if liver enzymes exceed 3× upper limit of normal or if hematocrit exceeds 54%.

Frequently Asked Questions

Citations

1. Pharmaceutical reference. 2004. Clinical pharmacology reference — Half-life approximately 1 day for liothyronine (T3)
2. Jonklaas J, Bianco AC, Bauer AJ et al.. 2014. Thyroid — ATA hypothyroidism treatment guideline: liothyronine plasma t½ ~1 day vs ~7 days for T4; supports split BID dosing to avoid supraphysiologic peaks
3. Klein I, Ojamaa K. 2001. N Engl J Med — Canonical thyroid-hormone-and-heart review: exogenous/endogenous excess T3 increases heart rate, LV mass, atrial fibrillation risk; underlies cardiac-strain warnings for supratherapeutic dosing
4. Sawin CT. 2002. Thyroid — Subclinical hyperthyroidism (suppressed TSH from exogenous T3) approximately triples atrial-fibrillation risk in adults ≥60; relevant to any PED protocol producing iatrogenic TSH suppression
5. Biondi B, Cooper DS. 2008. Endocr Rev — Comprehensive review: subclinical thyroid dysfunction has measurable cardiovascular and skeletal effects even with FT3/FT4 within range; supports CV monitoring during T3 cycles
6. Surks MI, Ortiz E, Daniels GH et al.. 2004. JAMA — Cooperating-societies scientific review on subclinical thyroid disease; treatment recommendations and risk thresholds underpin safety framing for exogenous T3 supraphysiologic use