Ipamorelin
Selective growth-hormone secretagogue · Pentapeptide ghrelin-receptor agonist
Ipamorelin is described in its founding 1998 paper as the first selective growth-hormone secretagogue — a pentapeptide ghrelin-receptor (GHS-R1a) agonist developed by Novo Nordisk that stimulates growth-hormone release from the pituitary with a selectivity rivaling GHRH itself. What distinguishes it in the literature is its clean endocrine profile: unlike the earlier GH-releasing peptides GHRP-2 and GHRP-6, controlled animal studies report it does not meaningfully raise cortisol, ACTH, or prolactin. It is also one of the better-characterized peptides in this class, with a genuine human intravenous pharmacokinetic study and a human Phase II clinical trial on record. Regulatory agencies classify it as an unapproved drug, and it is prohibited in sport at all times (WADA).
The short version
Ipamorelin is a lab-made peptide — a short, five-piece chain of amino acids — that signals the pituitary gland to release the body's own growth hormone.
Its main claim in the research is selectivity: it tends to nudge growth hormone specifically, without stirring up stress hormones like cortisol the way some older peptides in its family do. That selectivity was shown in animal studies, and it has also been measured in people and tested in a human clinical trial.
Despite reaching human trials, it was never approved as a medicine, and it is banned in competitive sport.
Molecular identity
Specs
- Molecular weight
- 711.9 g/mol
- Molecular formula
- C38H49N9O5
- Monoisotopic mass
- 711.39 Da
- CAS / UNII
- 170851-70-4 · Y9M3S784Z6
- Sequence (pentapeptide)
- Aib-His-D-2-Nal-D-Phe-Lys-NH₂PubChem CID 9831659
- Structure / class
- Selective GHS-R1a agonist (GHRP-class pentapeptide)PMID 9849822
- Molecular target
- GHS-R1a (ghrelin receptor) on pituitary somatotrophsPMID 9849822
- Regulatory status
- Not FDA-approved · WADA S2 prohibitedFDA / research literature
Plain English
Mechanism
Ipamorelin is a selective agonist (a molecule that switches a receptor on) of the growth-hormone secretagogue receptor (GHS-R1a) — the same receptor the hunger hormone ghrelin acts on. Binding it triggers somatotroph cells (the pituitary cells that make growth hormone) in the anterior pituitary (the front lobe of the pea-sized hormone gland under the brain) to release a discrete pulse of growth hormone. It was derived from the earlier secretagogue (a compound that prompts a gland to release a hormone) GHRP-1 by removing a central Ala-Trp dipeptide (a two-amino-acid piece).
The founding study reported it as the first GHS-receptor agonist with a selectivity for growth-hormone release similar to that of GHRH (growth-hormone-releasing hormone — the body's own natural trigger for GH). In conscious swine (pigs), none of the secretagogues tested affected FSH, LH, prolactin, or TSH (other pituitary hormones controlling reproduction, milk, and the thyroid), and ipamorelin did not release ACTH or cortisol (the body's main stress hormones) at levels significantly different from GHRH stimulation — even at doses well above its GH-releasing potency. This clean separation from the stress-hormone axis (the hormonal chain that runs the stress response) is the basis for its reputation as the selective member of the GH-secretagogue family, in contrast to GHRP-2 and GHRP-6 (related but less selective peptides that do nudge cortisol and prolactin).
In human dosing, a single intravenous administration (an injection straight into a vein) produced one growth-hormone secretory episode (a single burst of GH release) peaking near 40 minutes and declining exponentially (tapering off steadily), with dose-proportional pharmacokinetics — meaning a bigger dose produced a proportionally bigger blood level.
Sources:PMID 9849822PMID 10496658
Why people reach for it
Potential benefits
Ipamorelin is the clean GHRP most people start with in this class — here's what draws them to it.
- A clean GH nudge without the stress-hormone cost — Its headline appeal. Its founding paper titled it the first selective GH secretagogue — in animal studies it releases GH with a selectivity rivaling GHRH while leaving cortisol, ACTH, and prolactin essentially untouched, unlike GHRP-2 and GHRP-6.
- Raise your own GH, not inject it — It signals the pituitary to fire its own GH pulse through the ghrelin receptor, so the body's natural feedback and rhythm stay in the loop rather than being overridden by outside hormone.
- Minimal hunger and minimal prolactin — Because it's the selective member of the family, it largely avoids the appetite spike and prolactin rise that make GHRP-6 and GHRP-2 harder to run — a big part of why it's the go-to GHRP.
- Leaner body composition and recovery support — The GH/IGF-1 rise is what people reach for it for — lean body-composition, training recovery, and sleep-quality goals, where IGF-1 drives protein synthesis.
- The canonical bedtime partner for a GHRH analog — It pairs with a GHRH peptide for a bigger combined pulse than either alone — most commonly CJC-1295, the classic CJC-1295 + Ipamorelin night stack.
- One of the better-studied peptides in its class — Unusually for this category it has a real human intravenous PK study and a human Phase II trial on record — though that trial was for post-surgical bowel recovery, not body composition.
Sources:PMID 9849822PMID 10496658PMID 25331030
What people reach for Ipamorelin for, drawn from what the research reports and how it's used — not proven outcomes or medical claims.
Implied timing
Best time to dose
Implied best time
Bedtime (empty stomach)
Most people inject Ipamorelin at bedtime on an empty stomach, riding the body's largest natural GH pulse.
- Ipamorelin amplifies the body's own GH release, and the single largest natural GH pulse fires in early slow-wave (deep) sleep — a bedtime dose stacks the peptide's pulse on top of that nocturnal surge rather than competing with it.
- Food is the reason for the empty stomach: a meal raises insulin and somatostatin (GH's off-switch), both of which blunt the pulse, so the dose goes ~2 hours clear of eating. This empty-stomach rule is the single most important execution variable.
- A fasted-AM dose (before cortisol fully rises) and a pre-workout dose are the common second and third injections on twice- or thrice-daily protocols — but the bedtime dose is the anchor.
- Its terminal half-life is short (~2 h in the human IV study, GH peaking near 40 min), so the value is in the discrete pulse each injection triggers; placing the key pulse at the overnight recovery window is where it's most useful.
No study establishes an ideal time of day for Ipamorelin — this is reasoned from its GH-secretagogue mechanism and how it's used. As a rule of thumb peptide dosing lands in the midday-to-evening window; for Ipamorelin the lean is bedtime, fasted.
Sources:PMID 10496658
How to run it
Dosing & protocol
The most important execution detail for any GH secretagogue is timing: inject on an empty stomach — most commonly at bedtime — to stack with the body's largest natural nighttime GH pulse. Food raises insulin and somatostatin (the body's GH off-switch), both of which blunt the pulse ipamorelin triggers. Keep a ~2-hour food window around the dose. Everything below is community and practitioner convention, extrapolated from GH-axis pharmacology and the published IV data — there is no validated subcutaneous human dose.
Community convention, not trial-proven: the human studies used the IV route, and the Phase II trial failed its efficacy endpoint. Ipamorelin is not FDA-approved for body-composition or anti-aging use and is WADA S2 prohibited at all times. Every practical number here is a usage pattern, not a validated prescription.
Tiered dose ranges
Ipamorelin is dosed by individual injection, typically one to three times daily SC. Dose per injection, not per day.
- Low / introductory:
- 100–150 mcg per injection — used when starting out, to gauge tolerance and confirm the clean endocrine profile on this individual.
- Standard:
- 200–300 mcg per injection — the most common community range; aligns with this page's calculator default (200 mcg) and the scale of the human PK study doses.
- Higher-frequency approach:
- 200–300 mcg, 2–3× daily (e.g., bedtime + fasted AM, or bedtime + fasted AM + pre-workout) — more injections, not a higher per-dose amount. Each dose must be on an empty stomach; spacing is typically 4–6 hours between injections.
Subcutaneous administration
Inject into subcutaneous fat — a shallow pinch of skin away from muscle. Site, timing, and the food window are the actionable choices.
- Injection site:
- Abdomen (2–3 cm clear of the navel), love-handle area, or outer thigh. Rotate sites between doses to prevent local irritation and lipohypertrophy (small fatty deposits from repeated injections at one spot).
- Measuring the dose:
- Drawn on a U-100 insulin syringe from the reconstituted vial. At the standard mix (5 mg vial + 2 mL BAC water = 2,500 mcg/mL): 200 mcg = 8 IU · 250 mcg = 10 IU · 300 mcg = 12 IU. The calculator on this page handles any vial size.
- Time of day:
- Bedtime is the primary injection time — the body's largest natural GH pulse occurs in the first hours of deep sleep; ipamorelin stacks with it rather than competing. A fasted-AM injection is the common second dose for twice-daily protocols (before breakfast, before cortisol has risen fully). A pre-workout dose is the third option in a 3× protocol.
- Food window:
- Wait at least 90–120 minutes after a meal before injecting. Avoid carbohydrate- or fat-heavy meals for 2 hours after the dose. Insulin and somatostatin are both elevated by food and both suppress the GH pulse — the empty-stomach rule is the single most important execution variable.
Cycle & washout
GH secretagogues are run in defined cycles, not indefinitely — thought to preserve pituitary sensitivity and somatostatin regulation.
- Standard cycle:
- 8–12 weeks of daily use. Ipamorelin's selectivity makes longer runs common; 12-week cycles are frequently reported with no significant side effects in the community literature.
- Washout:
- 4–6 weeks off between cycles. During the washout, GH and IGF-1 levels return toward baseline. Tracking IGF-1 at the end of a cycle (before washout) gives a useful signal of how the axis responded.
- Standalone vs. stacked:
- In standalone use, once-daily bedtime is standard. In a GHRH+GHRP stack (e.g., with CJC-1295), the same cycle length applies and both are dosed simultaneously.
Reconstitution at a glance
The on-page calculator does this live; the quick reference for this page's default 5 mg vial:
- Mixing:
- 5 mg vial + 2 mL bacteriostatic water = 2,500 mcg per mL. On a 100-unit (1 mL) U-100 insulin syringe: 200 mcg = 8 IU · 250 mcg = 10 IU · 300 mcg = 12 IU · 500 mcg = 20 IU.
Substrate the signal needs
Nutritional cofactor precision
Ipamorelin is the clean GHRP — its selectivity means it raises cortisol and prolactin minimally, so there is less "cost" to mitigate than with GHRP-2 or GHRP-6. The practical cofactor work is mostly about AMPLIFYING the GH pulse and SUPPLYING the substrate that pulse needs to build anything. Groups below map to the three mechanism questions.
Reasoned from GH/IGF-1-axis physiology and ipamorelin's GHS-R1a mechanism — not findings from an ipamorelin cofactor study. Supplement doses are common community ranges, not ipamorelin-specific evidence.
AMPLIFY / relieve the brake
Somatostatin is GH's off-switch. Nutrients that lower somatostatin tone produce a bigger pulse from the same ipamorelin dose.
- L-arginine:
- 3–6 g taken 30–60 minutes before injection — arginine suppresses somatostatin release, extending and deepening the GH pulse. Bedtime timing stacks with the overnight pulse; don't take it with a high-fat meal (blunts absorption).
- Glycine:
- 3–10 g before bed — a mild somatostatin inhibitor and sleep-quality support, which itself preserves the deep-sleep GH peak. Taken with the bedtime ipamorelin dose.
- Alpha-GPC (choline):
- 300–600 mg taken 30 minutes before injection — supports acetylcholine tone in the hypothalamus, which modestly amplifies GH pulse amplitude. Particularly relevant for the pre-workout dose if cognitive clarity is also a goal.
MITIGATE the cost
Ipamorelin's clean profile means minimal cortisol/prolactin cost vs. other GHRPs. The residual cost to manage is the transient rise in blood glucose GH itself causes.
- Berberine:
- 500 mg with meals — supports insulin sensitivity; counters the transient glucose elevation GH pulses cause. Take with food, not around the ipamorelin dose (you want low insulin at dose time).
- Alpha-lipoic acid (ALA):
- 300–600 mg with meals — antioxidant with mild insulin-sensitizing effect, complementary to berberine. Take at meals, not fasted-dose timing.
- Magnesium glycinate:
- 300–400 mg before bed — supports deep (slow-wave) sleep, when the largest natural GH pulse occurs. Pairs directly with the bedtime ipamorelin dose.
SUPPLY the substrate
A GH/IGF-1 signal builds lean tissue only if protein and key minerals are available. These are the raw materials.
- Protein intake:
- 1.6–2.0 g per kg of body weight per day (≈ 0.7–0.9 g/lb) — IGF-1 drives protein synthesis, so without sufficient protein and leucine the anabolic signal arrives with little to build from. Distribute across 3–4 meals for maximal muscle protein synthesis.
- ZMA (zinc + magnesium + B6):
- Zinc 25–30 mg + magnesium 400–500 mg + vitamin B6 10 mg, taken 30–60 minutes before bed — ZMA supports GH-axis signaling and deep sleep simultaneously; low zinc tracks with lower IGF-1. Avoid taking ZMA alongside calcium (competes for absorption).
- Vitamin D3 + K2:
- Vitamin D 2,000–5,000 IU daily (dose to 40–60 ng/mL blood level) + vitamin K2 100–200 mcg — vitamin D associates with healthy IGF-1 levels and musculoskeletal tissue; K2 directs calcium into bone rather than soft tissue during the GH-driven remodeling phase.
Combinations + timing
Stacking notes + timing windows
Ipamorelin acts at GHS-R1a (the ghrelin receptor). The canonical synergistic partner is a GHRH analog, which acts at GHRH-R — a completely different receptor on the same somatotroph cell. These two signals are multiplicative, not additive: together they produce a larger GH pulse than either alone. Pairing ipamorelin with another GHRP (GHRP-2, GHRP-6, hexarelin) is redundant — same receptor, same lever — and sacrifices ipamorelin's clean cortisol profile for no gain.
User combinations reasoned from complementary receptor pharmacology — not regimens studied head-to-head. WADA S2 prohibited; not FDA-approved for body-composition or anti-aging. "Reached for" describes where users go, not a proven indication.
Ipamorelin + CJC-1295
The canonical GH stack: the GHRP + GHRH pairing. The most widely used combination in this class for body-composition and recovery goals.
- Why it works:
- CJC-1295 is a GHRH analog (binds GHRH-R); ipamorelin binds GHS-R1a — two distinct receptors on the same pituitary somatotroph. The GHRH input primes the cell and raises cAMP; the ghrelin-receptor input triggers IP3/DAG signaling. Together they produce a synergistic pulse the founding study's receptor logic predicts: bigger than either alone, not just additive. CJC-1295 DAC (with Drug Affinity Complex) provides a sustained GHRH signal via albumin binding; ipamorelin provides pulsatile GHS-R1a stimulation on top of it.
- The protocol:
- Ipamorelin 200–300 mcg SC + CJC-1295 100–200 mcg SC, co-injected once daily at bedtime (or twice daily, with both peptides drawn into the same syringe for one stick). CJC-1295 DAC is sometimes dosed 2× per week instead of daily, in which case ipamorelin continues daily and the two overlap on injection days.
- Outcome:
- The combination most users reach for on lean body-composition, recovery, and anti-aging GH optimization goals — the GHRH+GHRP pairing that mirrors the body's own two-signal GH release physiology.
Ipamorelin + Sermorelin
A lower-intensity GHRH alternative — sermorelin is a shorter GHRH fragment with a less sustained profile, sometimes preferred for more physiologic (less amplified) GH release.
- Why it works:
- Sermorelin (GHRH 1-29) binds the same GHRH-R as CJC-1295 but has a shorter half-life and a more pulse-shaped profile — some practitioners prefer it for milder, more physiologically-patterned GH release, particularly in older users or those newer to GH secretagogues. The receptor complementarity with ipamorelin is identical.
- The protocol:
- Ipamorelin 200–300 mcg SC + sermorelin 200–500 mcg SC, co-injected at bedtime. Both are short-acting; once daily at bedtime is standard for this pairing.
- Outcome:
- Reached for when a more conservative or physiologic-feeling GH profile is wanted — same GHRH+GHRP synergy as the CJC-1295 pair, lower amplitude.
Ipamorelin + BPC-157 + TB-500
The recovery trio: ipamorelin provides a GH/IGF-1 anabolic backdrop; BPC-157 and TB-500 work locally on injured tissue.
- Why it works:
- BPC-157 supports gut lining, angiogenesis (new blood vessel growth), and tendon/ligament repair through local growth-factor signaling. TB-500 (thymosin β4) promotes cell migration into injury sites. Ipamorelin's systemic GH/IGF-1 rise provides the anabolic and anti-inflammatory backdrop that both local peptides work against. Three different levers — systemic GH signal, local repair signal, cell-migration signal — not redundant.
- The protocol:
- Ipamorelin 200–300 mcg SC at bedtime (standalone or stacked with CJC-1295) + BPC-157 250–500 mcg SC once daily + TB-500 on its own loading schedule (typically 2–5 mg per week for the first 4–6 weeks, then 2 mg per week maintenance). Rotate injection sites across the three.
- Outcome:
- Reached for on soft-tissue injury recovery and post-surgery healing goals, where systemic GH support and local repair signaling are wanted simultaneously.
Reconstitution math
Reconstitution calculator
Reconstitution calculator
Calculated for a 1 mL U-100 insulin syringe (100 units/mL).
Units per dose
8
Draw to this mark on a U-100 syringe
- Volume per dose
- 0.08 mL
- Doses per vial
- 25
- Concentration
- 2.5 mg/mL
One vial lasts
- Daily
- 25 days
- Every other day
- 50 days
- 5×/week
- 35 days
Research use only. Not for human consumption. Outputs are reference values based on research literature — verify all measurements independently.
From the studies
Side effects from research
The strongest human safety statement comes from the Phase II trial (mid-stage human study): intravenous ipamorelin at 0.03 mg/kg twice daily for up to seven days was reported as well tolerated across 114 surgical patients, with safety assessed by adverse-event monitoring (tracking any harms) and laboratory tests.
The supporting preclinical (animal and lab, pre-human) selectivity data are also safety-relevant — in swine (pigs), ipamorelin did not significantly elevate ACTH, cortisol, prolactin, or the gonadotropins (the stress and reproductive hormones) even above its GH-releasing dose. No formal long-term toxicology dossier (a full battery of safety studies) or LD50 (the dose fatal to half of test animals) was located in the primary literature, so the defensible safety picture is limited to that short-term human exposure and the animal selectivity findings.
Sources:PMID 25331030PMID 9849822
As reported in literature
Research dosing ranges
These are the doses actually used in the published studies — the evidence the practical figures above lean on, shown separately so research data is never mistaken for a proven human dose. Reported doses span in-vitro (in lab dishes), rodent, swine (pig), and human studies. The human studies are an intravenous pharmacokinetic study and a Phase II clinical trial — there is no validated systemic dose for the research community's typical subcutaneous use. Potency values below are tagged by model; doses are often given per kilogram of body weight (1 kg ≈ 2.2 lb).
| Dose | Route | Model | Outcome | Sources: |
|---|---|---|---|---|
| EC50 1.3 nmol/L | In vitro | Rat pituitary cells | GH release (Emax ~85%) | PMID 9849822 |
| ED50 ~80 nmol/kg | Intravenous | Rat (anesthetized) | GH release | PMID 9849822 |
| ED50 ~2.3 nmol/kg | Intravenous | Swine (conscious) | GH release | PMID 9849822 |
| 4.21–140.45 nmol/kg | IV infusion (15 min) | Human (healthy, n=8/dose) | Dose-proportional GH release; t½ ~2 h | PMID 10496658 |
| 0.03 mg/kg twice daily | Intravenous | Human (Phase II, n=114) | Well tolerated; failed efficacy endpoint | PMID 25331030 |
Quick answers
Frequently asked
What makes Ipamorelin different from other GH secretagogues?
Selectivity. Its founding 1998 paper titled it the first selective growth-hormone secretagogue: in animal studies it stimulates growth-hormone release with a selectivity comparable to GHRH, without the rises in cortisol, ACTH, or prolactin reported for GHRP-2 and GHRP-6.
Has Ipamorelin been studied in humans?
Yes — more than most peptides in this category. There is a published human intravenous (into-a-vein) pharmacokinetic study (how the body handles the drug) and a Phase II clinical trial (a mid-stage human study) for post-operative ileus (a sluggish bowel after surgery). In that trial it was well tolerated but did not beat placebo (a dummy treatment) on its efficacy endpoint (the main measure of whether it worked).
How is Ipamorelin commonly dosed?
No human trial has set a subcutaneous dose, so there is no official one — the human studies all used the intravenous route. In practice, the common community pattern is 200–300 mcg per injection, subcutaneously, once to three times daily on an empty stomach. The single most important variable is timing: inject at bedtime (and/or fasted AM) to stack with the body's natural GH pulse, and keep a 2-hour food window — food raises insulin and somatostatin, both of which blunt the GH release ipamorelin triggers. Treat all of this as user convention extrapolated from GH-axis pharmacology, not a medical recommendation.
Is Ipamorelin an approved drug?
No. It is not approved for any indication, and a U.S. FDA advisory committee recommended against including it on the list of bulk substances permitted for pharmacy compounding. It is also prohibited in sport by WADA at all times. This page presents research literature only and makes no therapeutic claims.
What is Ipamorelin's half-life?
In a human intravenous study, the terminal plasma half-life was approximately 2 hours, with the growth-hormone response peaking near 40 minutes. No half-life has been characterized for oral or subcutaneous routes.
Why is Ipamorelin paired with CJC-1295?
Receptor complementarity. Ipamorelin acts at GHS-R1a (the ghrelin receptor); CJC-1295 acts at GHRH-R (the GHRH receptor) — two distinct receptors on the same GH-producing pituitary cell. The two signals are synergistic rather than additive: together they produce a larger GH pulse than either alone. This mirrors the body's own two-signal GH release logic and is the basis for the canonical ipamorelin + CJC-1295 pairing.
Primary sources
References
- PubChem CID 9831659PubChem CID 9831659 (Ipamorelin)
- PMID 9849822Raun et al., Eur. J. Endocrinol. 1998
- PMID 10496658Gobburu et al., Pharm. Res. 1999 (human PK)
- PMID 25331030Beck et al., Int. J. Colorectal Dis. 2014 (Phase II)
- NCT00672074ClinicalTrials.gov NCT00672074 (Phase II ileus)
- FDA 2024FDA PCAC briefing — Ipamorelin (2024)
- WADAWADA Prohibited List (S2, prohibited at all times)
Research use only · Not medical advice · Updated 2026-06-01