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Tirzepatide

Aliases: Mounjaro · Zepbound · LY3298176

Last verified: 2026-09-23

Approved drugStrong evidencePeptidesHigh interest

The short version

Tirzepatidee set a new bar: SURMOUNT-1 showed ~21% average body weight loss at the highest dose — a level previously achievable only by bariatric surgery. The SURPASS program confirmed superiority over semaglutide 1 mg in diabetes. The side-effect profile is class-typical (nausea ~20–30%), and long-term questions are the same as for the whole class: muscle loss, gallbladder complications, questions of chronic use. It is currently the most effective approved anti-obesity drug.

Identity & type

Molecular type
analog
Sequence / structure
39-mer, C20 diacid bočni lanac
Molecular weight
~4814 Da
Origin
Dual GIP/GLP-1 receptor agonist with weekly half-life; drugs Mounjaro, Zepbound.

Mechanism of action

GIPR + GLP-1R co-agonism → synergistic effects on insulin, appetite and adipose metabolism.

Dosing & routes

Official / clinical context

Approved drug — indications, dosing and warnings are defined by the official label. Titration 2.5 → 15 mg SC weekly.

Regulator-approved labeling and published study designs — never a recommendation.

Community-reported practice

Titration 2.5 → 15 mg SC weekly. Mounjaro/Zepbound: the strongest approved weight effect (~−20% in trials); users describe complete appetite control. GI side effects more frequent than semaglutide, but efficacy higher.

Unverified self-reports. Not medical advice. Not endorsement.

Expected effects (community)

Mounjaro/Zepbound: the strongest approved weight effect (~−20% in trials); users describe complete appetite control. GI side effects more frequent than semaglutide, but efficacy higher.

Protocol — official vs community

Official / label

Zepbound (obesity) / Mounjaro (T2D): 5–15 mg SC once weekly. Maintenance is 10 or 15 mg.

  1. 01Weeks 1–4: 2.5 mg weekly
  2. 02Weeks 5–8: 5 mg weekly
  3. 03If needed, increase in 2.5 mg steps ≥4 weeks apart
  4. 04Maintenance: 10 or 15 mg weekly

Duration: Chronic.

The 2.5 mg start is an initiation dose, not a maintenance dose.

Community (anecdotal)

Same structure; vial-based users often hold at 5–7.5 mg for cost or tolerability.

Cycle:
Continuous.
Break:
None.

SURMOUNT-5 showed ~20.2% vs semaglutide's 13.7% at equivalent titration — head-to-head, not extrapolated.

Human evidence

Robust: SURPASS 1–5 (diabetes), SURMOUNT 1–5 (obesity), SURMOUNT-5 (head-to-head vs semaglutide).

Preclinical evidence

The preclinical phase was completed and submitted to regulators as part of registration; pharmacology and toxicology details are part of the official label.

Known risks

  • Nausea, diarrhea, vomiting (~20–30%)characterized
  • Gallbladder complications; rarely pancreatitischaracterized
  • Muscle mass loss with large weight reductioncharacterized

Teal: characterized in clinical/labeling contexts. Amber: theoretical or reported outside controlled settings.

Unknowns & evidence gaps

  • Decades-long safety
  • Comparative efficacy vs newer triple agonists

Frequently asked questions

References

  1. Jastreboff A.M. et al., SURMOUNT-1 (N Engl J Med, 2022)
  2. Frias J.P. et al., SURPASS-2 (N Engl J Med, 2021)
  3. Aronne L.J. et al., SURMOUNT-5 (2025)