# How Long Ipamorelin Stays in Your System: Half-Life — Ipamorelin > How long does ipamorelin stay in your system? Terminal half-life is about 2 hours in humans; near-complete clearance ~8-10 hours. Detection in sport is separate. Cited. About a 2-hour terminal half-life in humans. One discrete GH pulse near 40 minutes. Detection in sport is a different clock. ## The short version How long does ipamorelin stay in your system? In humans, the terminal half-life — the time for blood levels to drop by half during the clearance phase — is about 2 hours [2]. Pharmacology uses a rule of thumb: after roughly four to five half-lives, a compound is mostly gone. That puts near-complete clearance of the parent peptide at about 8 to 10 hours. The growth-hormone response is even quicker and shorter: a single burst that peaks near 40 minutes after dosing [2]. So the felt 'pulse' is over fast, and the peptide itself clears within hours, not days. One important caveat: how long it stays detectable in an anti-doping test is a separate question from how long it stays active, and the detection window can outlast clearance. Those two clocks are not the same, and the sections below keep them apart. ## The human half-life number The 1999 population PK/PD study is the source. In healthy male volunteers (n=8 per dose level), across five 15-minute IV infusions from 4.21 to 140.45 nmol/kg, the kinetics were dose-proportional [2]. The headline figures: terminal half-life about 2 hours, clearance 0.078 L/h/kg, steady-state volume of distribution 0.22 L/kg [2]. Dose-proportional means doubling the dose roughly doubled exposure — a clean, linear profile. This is the only human pharmacokinetic dataset of its kind for ipamorelin, which is why every credible half-life figure traces back to it. ## The GH pulse versus the peptide Two timelines run here, and they differ. The peptide's own clearance follows the ~2-hour half-life [2]. The growth-hormone response it triggers is a single discrete pulse that peaks near 0.67 h — about 40 minutes — after dosing [2]. So the GH signal rises and falls quickly on its own schedule, while the peptide concentration decays separately. Neither persists for days. The GH pulse is the measured pharmacodynamic event; community claims of multi-day 'GH elevation' from a single ipamorelin dose are not supported by this kinetic profile. ## Clearance in animals Animal data is consistent with rapid clearance. In rats, ipamorelin's plasma clearance is roughly 5-fold lower than GHRP-6 — meaning it lingers somewhat longer than that older peptide, but still clears on a short timescale rather than accumulating. The ipamorelin-derived oral analog NN703 showed a longer 4.1-hour half-life in dogs [7], but that is an engineered, structurally modified molecule built specifically for oral durability — not ipamorelin itself. The parent peptide's profile is the short one. ## Detection is a different clock Clearance and detectability are not the same. Ipamorelin is prohibited in sport at all times under the WADA Prohibited List, category S2, as a growth hormone secretagogue, and accredited anti-doping laboratories detect it in urine. A 2026 critical review specifically notes that ipamorelin's short half-life creates analytical challenges for detection, even as the testing framework expands [13]. The practical point: a roughly 2-hour active half-life [2] does not mean a 2-hour detection window. Detection methods target the parent compound or its signature in urine and can register it outside the active window. This site does not provide detection-window estimates — it notes only that the two clocks differ and that detection is established. --- A tolerability-first readout of the ipamorelin record — the cortisol-sparing GH pulse logged where the studies confirm it, the lone failed human trial and the missing long-term safety left in plain view, and the community reports held to one side as anecdote; the 'order' here orders the literature, never a checkout, and nothing on this console is dosed, dispensed, or sold.