How long do peptides stay in your system?

“How long do peptides stay in your system?” sounds like one question, but the honest answer is a range that runs from minutes to weeks, and for many of the peptides people talk about most, nobody knows. This page collects the half-lives that have actually been measured, in published studies or on FDA labels, and marks plainly where the data stops. It is a reference for how long a substance persists in the body, not a dosing guide. Every figure links to its source, and it is educational only, not medical advice.

How long do peptides stay in your system?

It depends almost entirely on the peptide’s elimination half-life. Among the compounds with published human data, half-lives run from about 8 minutes (tesamorelin) to roughly a week (semaglutide). A standard pharmacology rule says a drug is effectively eliminated after four to five half-lives, so tesamorelin is largely gone within an hour, while a week-long half-life means weeks. For BPC-157, TB-500 and most research peptides, no human half-life has been published at all.

What does “half-life” mean?

The elimination half-life is “the time required for the concentration of a specific substance, typically a drug, to decrease to half of its initial amount in the body,” according to the StatPearls pharmacology reference on the National Library of Medicine’s bookshelf (Hallare and Gerriets, StatPearls). The same reference explains why half-life answers the “how long” question: about 90% of a drug is eliminated after roughly 3.3 half-lives, 94% to 97% after 4 to 5, and after 4 to 5 half-lives the concentration “typically falls below a clinically relevant concentration and is considered effectively eliminated” (StatPearls).

Two caveats matter for peptides. First, that rule describes the drug in your blood, not its effects, which can outlast it (covered below). Second, a half-life measured in one setting, such as an intravenous infusion in healthy men, may not match what happens after an injection under the skin or in a different person.

Peptide half-life reference table

Every half-life below comes from a published human study or an FDA label. The “roughly gone after” column is our own arithmetic using the four-to-five half-life rule above, not a measured value, except for semaglutide, where the label states the figure itself.

Semaglutide and tirzepatide are not peptides sold in the research market, but they are the long-acting peptide drugs most readers know, so they anchor the scale.

Why some peptides clear in minutes and others last weeks

Peptides are short chains of amino acids, and enzymes can cut them apart. In the first published pharmacokinetic study of BPC-157, done in rats and dogs, the peptide “was rapidly metabolized into a variety of small peptide fragments” that broke down into single amino acids and entered normal amino acid metabolism, leaving mainly through urine and bile (He et al., 2022). A rat study of Semax described the same pattern of rapid enzymatic degradation (Shevchenko et al., 2006).

Long-acting peptides are modified to last longer. The CJC-1295 trial authors note that therapeutic use of natural growth hormone-releasing hormone “is limited by its short duration of action” and describe CJC-1295 as a long-acting analog (Teichman et al., 2006). A 2026 review describes the DAC in CJC-1295 with DAC as albumin-binding, and lists no human half-life for the version without it (Dominikowski et al., 2026), which is why “CJC-1295” with and without DAC should not be treated as one compound; our CJC-1295 overview explains the split. Tirzepatide’s label says it carries a fatty-acid chain that “enables albumin binding and prolongs the half-life” (Zepbound prescribing information); its half-life, like those of semaglutide and retatrutide, is measured in days.

Half-life is not the same as how long the effect lasts

How long a peptide stays in your blood and how long its effects last are separate questions, and the published studies show the gap clearly:

• CJC-1295. After a single injection, growth hormone rose 2- to 10-fold for 6 days or more and IGF-1 rose 1.5- to 3-fold for 9 to 11 days. After multiple doses, IGF-1 stayed above baseline for up to 28 days (Teichman et al., 2006).
• Ipamorelin. Each infusion produced a single burst of growth hormone, and the drug itself had a 2-hour terminal half-life (Gobburu et al., 1999). More detail is on our ipamorelin page.
• Tesamorelin. It has a half-life of minutes, yet in the label trials in HIV-infected adults with lipodystrophy, daily use over 26 weeks reduced visceral fat, and visceral fat rose again in people switched to placebo for the next 26 weeks (Egrifta SV label). See our tesamorelin overview.
• BPC-157. A 2025 review notes that despite a half-life under 30 minutes, the processes it starts “appear to persist for weeks to months in animal studies” (McGuire et al., 2025). That is animal data, not human. Our sister site covers the gap in how long BPC-157 takes to work.

So “it’s out of my system” and “it has stopped doing anything” are not the same claim, in either direction.

How long does BPC-157 stay in your system?

Nobody has measured it in people. The first published pharmacokinetic study, in rats and beagle dogs, found an elimination half-life under 30 minutes after intravenous and intramuscular dosing, with the peptide broken down into fragments and amino acids (He et al., 2022). The one published human intravenous study, which gave infusions to two adults, measured safety blood work and reported no blood-level data in its abstract (Lee and Burgess, 2025). Applying animal numbers to people is a guess, not a finding. For the wider evidence picture, see our BPC-157 overview.

What is the half-life of retatrutide?

About six days. In a 12-week, Lilly-funded phase 1b trial of 72 adults with type 2 diabetes, the investigators reported that retatrutide’s pharmacokinetics were dose proportional “and its half-life was approximately 6 days” (Urva et al., 2022). By the four-to-five half-life rule, that suggests roughly a month to clear after the last dose, similar to tirzepatide and a little shorter than semaglutide’s labeled 5 to 7 weeks. Retatrutide is still investigational; our retatrutide overview covers its trial results.

What is the half-life of tesamorelin?

Minutes. The current labels list a mean elimination half-life of 8 minutes for Egrifta SV and 11 minutes for Egrifta WR in healthy adults after a single injection under the skin (Egrifta SV label; Egrifta WR label). The labels also report that peak blood levels arrive about 0.15 hours (roughly nine minutes) after injection, and that absolute bioavailability of the original formulation was under 4% in healthy adults.

What are the half-lives of ipamorelin and CJC-1295?

Ipamorelin’s terminal half-life was 2 hours in a published human pharmacokinetic study that gave it as an intravenous infusion to healthy men (Gobburu et al., 1999). CJC-1295 with DAC had an estimated half-life of 5.8 to 8.1 days in healthy adults (Teichman et al., 2006). CJC-1295 without DAC has no half-life reported in human studies (Dominikowski et al., 2026).

What is the half-life of TB-500?

It has not been measured in people. TB-500 is a synthetic fragment related to thymosin beta-4 (our TB-500 overview explains the difference), and the human data that exists is for the full protein: in a phase 1 trial of recombinant thymosin beta-4 given intravenously to healthy volunteers, half-lives ranged from 0.5 to 2.08 hours (Wang et al., 2021). An earlier trial of synthetic thymosin beta-4 found the half-life increased as the dose increased (Ruff et al., 2010). Neither tells you how the fragment behaves.

What the community gets right, and where it guesses

Half-life comes up most in community threads as a way of telling products apart. In the X posts our tracker collected about CJC-1295 (17 posts, July 13 to 19, 2026), users describe the DAC and no-DAC versions as effectively different peptides with different half-lives, some favoring DAC for less frequent injections and others warning that it keeps growth hormone elevated continuously rather than in pulses. The first half fits the published data, which show a 5.8-to-8.1-day half-life for the DAC version and no human half-life at all for the version without it; the second is a user concern, not something the trial tested. More is on our CJC-1295 community page.

In the TB-500 set (16 X posts, July 14 to 19, 2026), commenters stress that TB-500 is a fragment rather than the full 43-amino-acid protein, and one user claims most blends sold as TB-500 actually contain full-chain thymosin beta-4, which they describe as having a different half-life. We could not verify what is inside any product, and since the fragment’s human half-life has never been published, no one can say how different it is. See our TB-500 community page.

These are self-reports from one platform over short windows, not evidence. The pattern worth noticing is how often half-life figures for research peptides circulate online with no human study behind them.

The bottom line

Where human data exists, peptide half-lives span a wide range: minutes for tesamorelin, about 2 hours for ipamorelin, roughly a week for CJC-1295 with DAC, retatrutide, semaglutide and tirzepatide. Multiply by four to five for a rough sense of when a drug is effectively gone. For BPC-157, TB-500, Semax, Selank, MOTS-c, Epitalon and injectable GHK-Cu, the honest answer is that it has not been measured in people, and any confident number you see is extrapolated from animals or simply unsourced. If timing matters for your health, medications or testing, that is a question for a clinician who can see your full picture.

Status: of the compounds in this table, tesamorelin (as Egrifta, for HIV-related abdominal fat), semaglutide and tirzepatide are FDA-approved drugs; retatrutide is investigational; the rest are not FDA-approved. What this status means.

Educational information only, not medical advice. Half-life figures are as reported in the cited sources as of October 12, 2026; “roughly gone after” values are our arithmetic from those figures.