T3 (Cytomel/Liothyronine) — Dosing, Cycles, Half-Life & Side Effects
T3 (Cytomel/Liothyronine) is a thyroid hormone with a half-life of 24 hours. Active thyroid hormone for metabolic enhancement and fat loss, suppresses natural thyroid function. This page is educational harm-reduction reference compiled from peer-reviewed literature — not medical advice, not an endorsement, not a recommendation to use. Consult a licensed clinician before any decision.
Quick Facts
| Class | Thyroid Hormone |
|---|---|
| Half-life | 24 hours |
| Detection window | 7 days |
| Hepatotoxicity | Low |
| Suppression | 0/10 |
| Administration | oral |
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 — cardiovascularT3 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
What is the half-life of T3 (Cytomel/Liothyronine)?
T3 (Cytomel/Liothyronine) has a half-life of approximately 24 hours. Clearance estimate: 24h × 5 = 120h = 5 days. This figure is used to determine injection frequency (for esters) and post-cycle clearance timing.
What is the typical dose range for T3 (Cytomel/Liothyronine)?
Commonly reported ranges for T3 (Cytomel/Liothyronine): 12.5-50mcg/day. Cycle length: 4-8 weeks with taper. These are compiled from published studies and community-reported usage — individual response varies and lower end is always preferred.
Does T3 (Cytomel/Liothyronine) suppress natural testosterone?
T3 (Cytomel/Liothyronine) causes minimal suppression of the HPTA axis (score 0/10). PCT may still be advisable depending on stack and duration.
Is T3 (Cytomel/Liothyronine) liver toxic?
Hepatotoxicity rating: Low. Non-17αα compound — liver stress is lower but still warrants periodic monitoring during a cycle.
What is T3 (Cytomel/Liothyronine) typically used for?
T3 (Cytomel/Liothyronine) is commonly used for: Cutting, Pre-competition, Metabolic support. Intended-use context does not imply safety — every use case carries the same underlying pharmacological risks.
Citations
Disclaimer
StackItSmart is an independent harm-reduction reference. The content above is compiled from peer-reviewed literature and is not medical advice, not an endorsement, and not a recommendation to use T3 (Cytomel/Liothyronine). Performance-enhancing compounds carry legal, endocrine, cardiovascular, and hepatic risks. Consult a licensed clinician before any decision. StackItSmart does not provide sourcing, procurement, or dosing prescriptions.