# How Long Ipamorelin Stays in Your System: Half-Life > How long does ipamorelin stay in your system? The human half-life is about two hours. A clinical-lens read of the pharmacokinetics, the GH pulse timing, and what it means. About two hours in humans — what that number means for the drug, the growth-hormone pulse, and anti-doping detection. ## The short version How long does ipamorelin stay in your system? In people, the terminal half-life is about two hours [2]. Half-life is the time it takes for the amount in your blood to fall by half. After roughly four to five half-lives — eight to ten hours — most of a single dose is effectively gone. So as a molecule, ipamorelin clears fairly fast. There are two important wrinkles. First, the *effect* and the *molecule* are not the same: ipamorelin triggers a single growth-hormone pulse that peaks about 40 minutes after dosing [2], and that downstream signal plays out on its own timeline. Second, "out of your blood" is not "undetectable to a drug test" — anti-doping labs can detect growth hormone secretagogues even after the parent peptide has cleared. This page works through all three layers, with every number tied to the human study that measured it. ## The two-hour half-life, measured in humans The half-life number comes from the one human pharmacokinetic study of ipamorelin. Gobburu and colleagues (1999) gave healthy men five 15-minute IV infusions ranging from 4.21 to 140.45 nmol/kg and modeled the results [2]. They found dose-proportional (linear) kinetics with a terminal half-life of approximately two hours, a clearance of 0.078 L/h/kg, and a steady-state volume of distribution of 0.22 L/kg [2]. Dose-proportional matters: it means doubling the dose roughly doubles the exposure without surprising non-linear jumps, at least across the range tested. Practically, a two-hour half-life means a single IV dose is largely eliminated within about a day. In rats, plasma clearance is roughly five-fold lower than the older peptide GHRP-6, but the human figure is the one to anchor on [2]. ## The GH pulse: a different clock The clinically interesting part is that the growth-hormone response runs on its own schedule, separate from how fast the peptide clears. After ipamorelin, GH rises as a single discrete pulse that peaks around 40 minutes (0.67 h) post-dose [2]. The peptide itself is largely gone within hours, but the GH it released — and the downstream effects of that pulse — outlast the molecule. This is the whole pharmacological design: a short-acting trigger that produces a clean, time-limited GH pulse rather than a sustained elevation. It is also why community protocols often time dosing around sleep, when the body's own GH secretion peaks — though that timing rationale is a practice, not a studied dosing instruction, and this site reports no human dose [3]. ## Detection and the anti-doping angle "Stays in your system" has a second meaning for anyone subject to drug testing, and here the answer is different. Ipamorelin is prohibited in sport at all times under the WADA Prohibited List, category S2 (peptide hormones and growth factors), as a growth hormone secretagogue [7]. Accredited anti-doping laboratories have established urine-detection methods for these peptides. A 2026 critical review of peptide use in sport specifically flagged ipamorelin's short half-life as an *analytical challenge* for detection — the parent peptide clears quickly — while noting that detection frameworks continue to expand [7]. In other words: the molecule's short blood half-life does not mean it is undetectable, and the detection window is not the same as the pharmacokinetic half-life. None of this is advice; it is the regulatory and analytical context tied to the published review. --- A tolerability-first console read of the ipamorelin literature — the reported side effects, the water-retention question, and the half-life logged plainly, the single failed human trial and the blank long-term-safety line kept in view; the 'md' names a reading lens, never a clinic, and nothing here is dosed, prescribed, or sold.