How long does Retatrutide stay in your system?
Retatrutide has a published half-life of approximately 6 days. By the standard pharmacology rule of thumb, a drug is about 97% eliminated after roughly five half-lives, which here works out to about 30 days (4.3 weeks). That figure comes from an early clinical trial, because retatrutide has no approved label yet.
Source: Urva et al., Lancet 2022 (PMID 36354040) · Peer-reviewed · measured: subcutaneous · dataset reviewed September 23, 2026
What is the half-life of Retatrutide?
Retatrutide's half-life of approximately 6 days comes from a phase 1b dose-escalation study of LY3437943 in people with type 2 diabetes, published in The Lancet in 2022 and measured after subcutaneous injection. Retatrutide is an investigational single peptide that activates three receptors: GLP-1, GIP and glucagon.
The trial also found its pharmacokinetics were dose proportional, meaning exposure rose in step with dose across the range studied, which supports treating one half-life figure as reasonable across those doses. Six days places retatrutide between tirzepatide, at approximately 5 days, and semaglutide, at approximately 1 week. All three are measured in days; what distinguishes them pharmacologically is which receptors they activate.
How much Retatrutide is left after each half-life?
Each half-life removes half of whatever is left, so the percentages are pure arithmetic and the same for any compound; only the clock changes. For Retatrutide, one half-life is 6 days. The rows below run that forward for a single amount with nothing added.
| Half-lives elapsed | Time elapsed | Remaining | Cleared |
|---|---|---|---|
| 1 | 6 days | 50% | 50% |
| 2 | 12 days | 25% | 75% |
| 3 | 18 days (2.6 weeks) | 12.5% | 87.5% |
| 4 | 24 days (3.4 weeks) | 6.25% | 93.75% |
| 5 | 30 days (4.3 weeks) | 3.13% | 96.88% |
| 6 | 36 days (5.1 weeks) | 1.56% | 98.44% |
| 7 | 42 days (6 weeks) | 0.78% | 99.22% |
Why do the numbers differ between sources?
Because retatrutide is still in phase 3, there is no prescribing information to check against. The only figure we cite comes from one early trial with its own population and dose range. Later trials may report different values, and if a label is eventually issued it will become the reference.
Figures quoted for research-use material sold under the retatrutide name have no clinical pharmacology behind them. Without verified identity and purity, there is no reason to assume a vial labelled retatrutide behaves like the molecule studied in the trial.
What does a half-life not tell you?
It does not describe the glucagon component's effects. Retatrutide's distinguishing feature is glucagon receptor activity, thought to raise energy expenditure and reduce liver fat, and the time course of those effects is a separate question from how fast the peptide is cleared.
It also says nothing about weight or safety outcomes, which come from the TRIUMPH phase 3 programme rather than from pharmacokinetics. And because a single-dose curve ignores accumulation, it understates what is present during repeated administration.
Can you run the numbers yourself?
The estimator applies the same decay arithmetic to any half-life, starting amount and time you enter. It opens with Retatrutide's published value loaded. Type another figure to see how sensitive the result is to it.
Published value: Approximately 6 days (Subcutaneous) · Urva et al., Lancet 2022 (PMID 36354040) · Compound profile
Show the math
What are the limits of this estimate?
Everything above is a single-compartment approximation: one pool of drug, falling by the same fraction in every interval. Real elimination varies with kidney and liver function, body composition, formulation and route, and a published figure describes only the route and the people it was measured in. Many compounds also show a fast distribution phase before the slower elimination the table describes.
A half-life is not a dosing schedule. Labelled intervals come from clinical trials that measured outcomes and tolerability, and nothing on this page suggests when to take, repeat or stop anything. Whether Retatrutide is out of your system for drug-testing purposes is a different question again. Tests often look for metabolites rather than the parent compound, and the answer depends on the assay, its sensitivity and the sample type, none of which a plasma half-life captures.
FAQ.
Is retatrutide's half-life from an FDA label?
No. Retatrutide is investigational and has no approved label. The figure of approximately 6 days comes from a phase 1b dose-escalation trial in people with type 2 diabetes, published in The Lancet in 2022, which also found its pharmacokinetics were dose proportional.
How does retatrutide's half-life compare with tirzepatide and semaglutide?
On the sources in our dataset, retatrutide is approximately 6 days, tirzepatide approximately 5 days and semaglutide approximately 1 week. All three are measured in days. Their pharmacological differences lie in which receptors they activate.
Does the published half-life apply to research-use retatrutide?
It cannot be assumed to. The trial figure describes the investigational drug made and supplied for that study. Material sold outside a trial is not verified for identity, purity or formulation, so its pharmacokinetics are unknown.
For what the evidence on Retatrutide actually shows, read the Retatrutide profile. For approval and regulatory position, see is Retatrutide legal. The half-life reference lists every sourced value side by side, including the compounds where a number circulates online with no reliable human data behind it.