Tirzepatide (Mounjaro/Zepbound) — Dosing, Cycles, Half-Life & Side Effects

Tirzepatide (Mounjaro/Zepbound) is a dual GIP/GLP-1 receptor agonist with a half-life of ~5 days (120 hours). FDA-approved dual GIP/GLP-1 receptor agonist for weight management. Not a PED — acts through appetite suppression and metabolic regulation. No HPTA interaction, no hepatotoxicity. Generally more effective than semaglutide for fat loss. Subcutaneous injection once weekly. 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

ClassDual GIP/GLP-1 Receptor Agonist
Half-life~5 days (120 hours)
Detection window30 days
HepatotoxicityNone
Suppression0/10
Administrationsubcutaneous

Typical Dosing Ranges

Common dose range: 2.5-15mg/week (titrate up over 4-8 weeks)

Cycle length: 12-52 weeks

Time to steady state: ~25 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: ~25 days post-last-dose before SERM start (5 × apparent depot half-life of 120h).
  • 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

  • GI side effects (nausea, diarrhea, constipation)
  • Very expensive (~$1000-1200/month without insurance)
  • Must maintain high protein intake to preserve muscle
  • Requires dose titration (4-8 weeks)
  • Potential muscle loss without resistance training

Known Interactions

No compound-specific interactions are catalogued in the current matrix. This does not mean no risk exists — it means there is no curated pairwise entry.

Related compounds

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 Tirzepatide (Mounjaro/Zepbound)?

Tirzepatide (Mounjaro/Zepbound) has a half-life of approximately ~5 days (120 hours). Clearance estimate: 120h × 5 = 600h = 25 days. This figure is used to determine injection frequency (for esters) and post-cycle clearance timing.

What is the typical dose range for Tirzepatide (Mounjaro/Zepbound)?

Commonly reported ranges for Tirzepatide (Mounjaro/Zepbound): 2.5-15mg/week (titrate up over 4-8 weeks). Cycle length: 12-52 weeks. These are compiled from published studies and community-reported usage — individual response varies and lower end is always preferred.

Does Tirzepatide (Mounjaro/Zepbound) suppress natural testosterone?

Tirzepatide (Mounjaro/Zepbound) causes minimal suppression of the HPTA axis (score 0/10). PCT may still be advisable depending on stack and duration.

What is Tirzepatide (Mounjaro/Zepbound) typically used for?

Tirzepatide (Mounjaro/Zepbound) is commonly used for: Weight management, Cutting (fat loss), Body recomposition, All experience levels. Intended-use context does not imply safety — every use case carries the same underlying pharmacological risks.

Is Tirzepatide (Mounjaro/Zepbound) legal?

Tirzepatide (Mounjaro/Zepbound) is a controlled substance in many jurisdictions (typically Schedule III in the US when it is an anabolic androgenic steroid). StackItSmart does not provide sourcing information. Possession, import, and use without a prescription carry legal consequences that vary by country and state.

Citations

  1. FDA prescribing information (Mounjaro/Zepbound). 2022. FDA NDA — Half-life approximately 5 days for tirzepatide SC injection
  2. FDA Mounjaro prescribing information. 2022. FDA drug label — Tirzepatide terminal half-life 5 days — supports weekly SC injection schedule; established via FDA-approved PK studies
  3. SURMOUNT + SURPASS trials (meta-analyzed in Zeng 2023). 2023. Frontiers in Endocrinology — Tirzepatide RCT dose range 2.5-15mg SC weekly; titration over 4-8 weeks required to minimize GI side effects
  4. FDA Mounjaro label + clinical trials. 2022. FDA drug label — Tirzepatide is non-hormonal (GIP/GLP-1 dual agonist); no HPTA suppression. suppressionScore 0/10
  5. FDA Mounjaro label. 2022. FDA drug label — Tirzepatide non-hormonal; no aromatization path. aromatizationRate 0/10
  6. FDA Mounjaro label + SURMOUNT/SURPASS safety data. 2022. FDA drug label — Tirzepatide hepatotoxicity events rare at RCT doses; ALT elevations infrequent. hepatotoxicity 1/10
  7. Jastreboff AM, et al. Tirzepatide Once Weekly for the Treatment of Obesity. N Engl J Med. 2022;387(3):205-216. PMID: 35658024
  8. Wadden TA, et al. Tirzepatide after intensive lifestyle intervention in adults with overweight or obesity. Lancet. 2024;403(10435):1417-1429

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 Tirzepatide (Mounjaro/Zepbound). 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.

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