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Retatrutide Half-Life: How Long It Stays in Your System

How long Retatrutide stays in the body, how that shapes dosing frequency, and what is known about drug testing.

Medically reviewed by Juan Pablo Frías, MD · · DisclosureGLP-1 / GIP / glucagon triple agonistUpdated
Half-life
approximately 6 days
subcutaneous, in people · Lancet 2022, PMID 36354040
Dosing interval
Once weekly
in clinical trials
WADA
Prohibited (S0)
In and out of competition
Detection window
Not found
None reported as of 2 Oct 2026

Retatrutide half-life

A half-life depends on the route (under the skin, into a vein, by mouth or nasal spray) and the species it was measured in, so we report each value with its route and source.

Retatrutide half-life by route
RouteHalf-lifeMeasured inSource
subcutaneousapproximately 6 daysPeopleLancet 2022, PMID 36354040

What half-life means

Half-life is the time it takes for the amount of a drug in the blood to fall by half. After one half-life, about 50% is left; after two, about 25%; after four to five, only a few percent remain.

  • A long half-life lets a drug be dosed less often, for example once a week.
  • A short half-life means levels rise and fall quickly, which is why some peptides are given daily or more often.
  • Effects can outlast blood levels, so half-life alone does not tell you how long a drug works.

What it means for dosing frequency

Retatrutide was dosed once a week in its clinical trials. Changing the interval changes how much drug builds up between doses, so it is not a free choice.

Drug tests and sport

Prohibited by WADA (S0)

Retatrutide is not named, and GLP-1/amylin class agonists are not listed. But it is an investigational drug with no approval in the sources we reviewed, and S0 prohibits drugs under clinical development that no authority has approved. If it is approved somewhere this would change.

Anti-doping labs use tests built for specific substances. Whether a given test detects Retatrutide, and for how long, is not reported in the anti-doping literature we checked (as of 2 Oct 2026). Tested athletes should treat it as prohibited (s0) at all times.

Common questions

How long does Retatrutide stay in your system?

Its reported half-life is approximately 6 days (subcutaneous). Most of a dose is gone after about four to five half-lives.

What is the half-life of Retatrutide?

Approximately 6 days (subcutaneous), from the source cited below.

Is Retatrutide on the WADA prohibited list?

Yes. Prohibited by WADA (S0).

More on Retatrutide

DosageDoses used in published trials, the titration pattern and a units chart.CalculatorVial, water and dose to syringe units.Side effectsWhat labels and studies report, and what is unknown.ResultsStudy outcomes and when they were measured.PricePrice per mg and per week from dated listings. No vendor links.Legal statusFDA, compounding and WADA status with dates.

Sources

  1. 1Retatrutide, a Triple Hormone Receptor Agonist, for Treatment of Obesity (TRIUMPH-1; Jastreboff AM et al.)New England Journal of Medicine · 2026PMID 42814954Accessed 2 Oct 2026
  2. 2Warning letter to NuScience Peptides LLC (ref. 733652), 24 Aug 2026, one of five letters to research-peptide sellers issued that dayU.S. Food and Drug Administration · 2026fda.govAccessed 2 Oct 2026
  3. 3World Anti-Doping Code International Standard Prohibited List 2026World Anti-Doping Agency · 2026wada-ama.orgAccessed 2 Oct 2026
  4. 4A Phase 2 Study of Once-Weekly LY3437943 Compared With Placebo in Participants Who Have Obesity or Are Overweight With Weight-Related Comorbidities (NCT04881760; arms and posted results)ClinicalTrials.gov (U.S. National Library of Medicine) · 2021clinicaltrials.govAccessed 2 Oct 2026
  5. 5World Anti-Doping Code: Prohibited List 2026World Anti-Doping Agency · 2026wada-ama.orgAccessed 2 Oct 2026
  6. 6LY3437943, a novel triple GIP, GLP-1, and glucagon receptor agonist in people with type 2 diabetes: a phase 1b, multicentre, double-blind, placebo-controlled, randomised, multiple-ascending dose trial.Lancet (London, England) · 2022PMID 36354040Accessed 2 Oct 2026
  7. 7Retatrutide in adults with obesity and type 2 diabetes (TRIUMPH-2): a double-blind, parallel-group, randomised, placebo-controlled, phase 3 trial.Lancet (London, England) · 2026PMID 42810372Accessed 2 Oct 2026
  8. 8Efficacy and safety of retatrutide, a GIP, GLP-1, and glucagon receptor agonist, in people with type 2 diabetes and inadequate glycaemic control with diet and exercise (TRANSCEND-T2D-1): a double-blind, randomised, phase 3 trial.Lancet (London, England) · 2026PMID 42250575Accessed 2 Oct 2026
  9. 9Retatrutide-Associated Improvements in Cardiovascular Risk Biomarkers in Adults With Obesity With or Without Type 2 Diabetes.Diabetes, obesity & metabolism · 2026PMID 42608321Accessed 2 Oct 2026

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