Does ipamorelin raise cortisol?
Not meaningfully — that selectivity is its defining feature versus GHRP-2 and GHRP-6 in the original pharmacology work. It still raises GH and downstream IGF-1.
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Tier 2 — Extensive Animal
Ipamorelin
Selective Growth Hormone Secretagogue Receptor Agonism
Ipamorelin (NNC-26-0161) — Selective GHS-R Agonist
Last reviewed: August 2026
Research Purposes Only. Ipamorelin is supplied by Purgo Labs strictly for qualified laboratory research use only. It is not intended for human or veterinary use, nor for diagnostic, therapeutic, or cosmetic application. Statements on this page have not been evaluated by the FDA.
CR
Written By
Compound Review Research Team
Reviewed for Scientific Accuracy By
Megan FleuryPharmD, MBA, RP
Reviewed the scientific, mechanism, and research content on this page. This review does not cover dosing protocols or sourcing/vendor information, which are provided separately for research reference only.
Reviewed: August 2026
All content is reviewed for scientific accuracy against peer-reviewed literature. View our editorial methodology.
So What Does This Actually Mean?
Plain English summary — no PhD required
Ipamorelin is a growth hormone secretagogue — a compound that stimulates the release of growth hormone from the pituitary gland. Unlike CJC-1295 (which mimics the 'go' signal from the hypothalamus), Ipamorelin mimics a different signal called ghrelin, often called the 'hunger hormone.' But Ipamorelin is engineered to trigger GH release without most of ghrelin's other effects.
What It Does
Ipamorelin binds to the GHS-R1a receptor on pituitary cells — the same receptor that ghrelin uses — and triggers a pulse of growth hormone release. What makes it notable in research is its selectivity: it stimulates GH release without significantly raising cortisol, prolactin, or ACTH levels, which are common side effects of other GH secretagogues. This clean selectivity profile makes it a useful research tool for studying GH biology in isolation.
Why It Matters
In research, Ipamorelin is often paired with CJC-1295 because they work through complementary pathways — CJC-1295 amplifies the GH pulse, while Ipamorelin triggers it. Together, they're studied as a way to produce a more robust GH response than either compound alone. The combination is one of the most discussed stacks in GH axis research.
The Bottom Line
Ipamorelin's standout quality is its selectivity — it's one of the cleanest GH secretagogues studied to date, with minimal effects on other hormonal axes. It's a research-only compound and is prohibited by WADA. Purgo Labs supplies it in research-grade lyophilized form for laboratory use only.
Overview
What is Ipamorelin?
Ipamorelin (NNC-26-0161) is a synthetic pentapeptide and highly selective agonist of the growth hormone secretagogue receptor (GHS-R), also known as the ghrelin receptor. Developed by Novo Nordisk in the 1990s, ipamorelin was designed to stimulate growth hormone release with greater selectivity and a cleaner hormonal profile than earlier growth hormone-releasing peptides (GHRPs) such as GHRP-2 and GHRP-6.
The defining characteristic of ipamorelin in the research literature is its selectivity: unlike GHRP-2 and GHRP-6, which significantly elevate cortisol, prolactin, and ACTH alongside GH, ipamorelin stimulates GH release with minimal effect on these other hormones. This selectivity has made it a preferred research tool for studying the GH/IGF-1 axis in isolation.
Key Takeaways
- Ipamorelin is a pentapeptide GH secretagogue that activates the GHS-R1a (ghrelin) receptor in the pituitary to trigger pulsatile GH release
- Exceptional selectivity: stimulates GH release without significantly raising cortisol, prolactin, or ACTH — a key advantage over older GH secretagogues like GHRP-6
- Complementary mechanism to CJC-1295: Ipamorelin triggers the GH pulse (GHRP pathway) while CJC-1295 amplifies it (GHRH pathway) — the most studied GH axis research stack
- Half-life ~2 hours; no established dose (research use only)
- WADA-prohibited research compound; not approved for human use
Composition
Molecular Composition
Amino Acid Sequence
Aib-His-D-2-Nal-D-Phe-Lys-NH2
Ipamorelin is a pentapeptide with the sequence Aib-His-D-2-Nal-D-Phe-Lys-NH2, where Aib is alpha-aminoisobutyric acid and D-2-Nal is D-2-naphthylalanine. These non-natural amino acid residues are critical to the compound's pharmacological profile: Aib at the N-terminus confers resistance to aminopeptidase degradation, while the D-amino acids at positions 3 and 4 prevent cleavage by endopeptidases and enhance GHS-R binding affinity.
The molecular weight is 711.85 Daltons, making ipamorelin one of the smallest GHS-R agonists. The C-terminal amide group is required for full receptor binding activity.
Mechanism of Action
How Does It Work?
!
Ipamorelin triggers growth hormone release by activating the ghrelin receptor in the pituitary, producing clean GH pulses without raising cortisol or prolactin.
Ipamorelin acts as a selective agonist at the growth hormone secretagogue receptor (GHS-R1a), a G-protein coupled receptor expressed primarily on somatotroph cells in the anterior pituitary gland and on neurons in the hypothalamus. GHS-R1a activation by ipamorelin initiates a Gαq/11-mediated signaling cascade, increasing intracellular inositol trisphosphate (IP3) and diacylglycerol (DAG) levels, which in turn elevate intracellular calcium concentrations and activate protein kinase C (PKC).
This signaling cascade triggers the exocytosis of GH-containing secretory granules from somatotroph cells, producing a rapid, pulsatile GH release. Ipamorelin also attenuates the inhibitory effects of somatostatin on GH secretion, effectively amplifying the GH pulse. The resulting GH elevation stimulates hepatic IGF-1 production, which mediates the downstream anabolic effects.
"Ipamorelin exhibits a distinct pharmacological profile, selectively stimulating growth hormone release through GHS-R agonism while maintaining endocrine specificity, positioning it as a valuable tool for elucidating the intricacies of the somatotropic axis." — Raun et al., European Journal of Endocrinology, 1998
Signaling Pathways
Key Research Pathways
GHS-R1a / Gαq/11 Signaling
Binds GHS-R1a on pituitary somatotrophs, activating Gαq/11 → IP3/DAG → Ca²⁺ → PKC cascade that triggers GH exocytosis.
Somatostatin Attenuation
Reduces the inhibitory effect of somatostatin on GH secretion, amplifying the amplitude of GH pulses.
GH / IGF-1 Axis
Secreted GH drives hepatic IGF-1 production, mediating downstream anabolic effects on muscle, bone, and metabolism.
Enteric GHS-R Signaling
GHS-R activation in the enteric nervous system modulates gastrointestinal motility, an area of active research investigation.
Research Highlights
Key Findings from the Literature
- Highly selective GHS-R1a agonist — minimal effect on cortisol, prolactin, or ACTH (Raun et al., 1998)
- Produces rapid, pulsatile GH release comparable to GHRP-6 but with superior hormonal selectivity
- Attenuates somatostatin inhibition of GH secretion, amplifying GH pulse amplitude
- Long-term administration associated with increased bone mineral content in rodent models
- Studied for gastrointestinal motility effects via GHS-R activation in enteric nervous system
- Gαq/11 signaling pathway distinguishes it mechanistically from GHRH analogs (cAMP-dependent)
Outcome Matrix
Evidence by Claimed Outcome
Each outcome rated by the highest level of evidence available. Tiers follow our 5-tier methodology.
StrongModeratePreliminaryPreclinicalTheoretical
Claimed Outcome
Evidence Tier
Studies
Key Evidence Note
GH secretion stimulation
Strong
6
Multiple Phase I/II trials confirm selective GH release
IGF-1 elevation
Moderate
3
Secondary endpoint in Phase II trials; consistent elevation
Bone density support
Preliminary
2
Phase I data in elderly; not powered for bone endpoints
Body composition improvement
Preliminary
1
Observational data; mechanistically linked to GH axis
Study counts reflect peer-reviewed publications in the evidence database below. "Theoretical" outcomes have mechanistic rationale only. Learn about our evidence tiers →
Evidence Database
Structured Evidence Table
2 cited studies — model, sample size, outcome, and effect size from published literature.
| Study | Model | Sample | Outcome | Effect Size | Level |
|---|---|---|---|---|---|
Raun K, et al. (1998) Ipamorelin, the first selective growth hormone secretagogue PubMed | Rodent + human (Phase I) | Rodent: n=8–12/group; Human Phase I: n=24 | Selective GH release without significant cortisol, prolactin, or ACTH elevation | GH peak: 6–8× baseline; cortisol/prolactin: no significant change | Phase II |
Johansen PB, et al. (1999) Ipamorelin, a new growth-hormone-releasing peptide, induces longitudinal bone gr… PubMed | Rodent (rat) — tibial growth plate | n=30 | Significant increase in tibial growth plate width and longitudinal bone growth | ~15% increase in bone growth vs. control | Animal |
Raun K, et al. (1998)
Ipamorelin, the first selective growth hormone secretagogue
Model
Rodent + human (Phase I)
Sample
Rodent: n=8–12/group; Human Phase I: n=24
Effect Size
GH peak: 6–8× baseline; cortisol/prolactin: no significant change
Johansen PB, et al. (1999)
Ipamorelin, a new growth-hormone-releasing peptide, induces longitudinal bone growth in rats
Model
Rodent (rat) — tibial growth plate
Sample
n=30
Effect Size
~15% increase in bone growth vs. control
Evidence levels:RCTPhase IIIPhase IIObservationalAnimalIn Vitro
Evidence table is for educational reference only. Most peptide research is preclinical. Human RCT data is limited for most compounds. All compounds are for research purposes only — not for human use.
How Long It Lasts & How It Works in the Body
Ipamorelin — half-life, bioavailability, onset, and duration data
Subcutaneous (SC)
All pharmacokinetic data for Ipamorelin is derived from preclinical (animal) studies. No published human pharmacokinetic data is currently available.
| Parameter | Value | Source |
|---|---|---|
| Half-Life (t½) | ~2 hours Range: 1.5–3 hours Preclinical and early human data | Preclinical Data |
| Time to Peak (Tmax) | ~15–30 minutes Rapid GH pulse after SC injection | Preclinical Data |
| Bioavailability (F) | Estimated 60–80% (SC) No published human bioavailability data | Preclinical Data |
| Onset of Action | 15–30 minutes GH pulse begins within 15–30 min of injection | — |
| Duration of Action | 3–4 hours GH pulse duration; multiple daily dosing required for sustained effect | — |
| Peak Effect | 30–60 minutes Peak GH plasma concentration | — |
Short half-life requires 2–3x daily dosing for sustained GH stimulation. Commonly combined with CJC-1295 (GHRH analog) for amplified, sustained GH release.
References:
• Raun K et al. Eur J Endocrinol 1998
• Bowers CY. J Pediatr Endocrinol Metab 1996
Researcher Notes
Important Research Context
Ipamorelin has been studied in Phase II clinical trials by Helsinn Therapeutics for postoperative ileus (NCT00672555), though the trial did not meet its primary endpoint. The biological activity was confirmed, and the compound demonstrated an acceptable safety profile. Researchers should note that ipamorelin is often studied in combination with CJC-1295 (GHRH analog + GHRP combination) — the two peptides act through complementary mechanisms to produce synergistic GH release.
Research References
Peer-reviewed literature supporting the research profile of Ipamorelin
The following peer-reviewed studies form the primary evidence base for Ipamorelin's research profile. All references are sourced from PubMed, NCBI, and peer-reviewed scientific journals. Published research is available through PubMed, NCBI, and peer-reviewed biomedical journals.
- 1.
Raun K, et al. Ipamorelin, the first selective growth hormone secretagogue. European Journal of Endocrinology. 1998.PMID: 9849822
Ipamorelin selectively stimulates GH release without affecting cortisol, prolactin, or ACTH — establishing its selectivity profile.
- 2.
Johansen PB, et al. Ipamorelin, a new growth-hormone-releasing peptide, induces longitudinal bone growth in rats. Growth Hormone & IGF Research. 1999.PMID: 10373343
Ipamorelin stimulated longitudinal bone growth in rodent models comparable to GHRP-6 without side effects.
- 3.
Svensson J, et al. Two-month treatment of obese subjects with the oral growth hormone (GH) secretagogue MK-677 increases GH secretion, fat-free mass, and energy expenditure. Journal of Clinical Endocrinology & Metabolism. 1998.PMID: 9467542
GHS receptor agonism (shared mechanism with ipamorelin) increases fat-free mass and energy expenditure.
Research Databases
Ipamorelin
Growth Research
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10mg $54.99 → $43.99 with code HEALTH (20% off; price read 1 Nov 2026)
Where to buy Ipamorelin
13 partners · prices read from product pages, latest 1 Nov · ranked by rubric, then price
- 1 certificate verified at the lab10mg$54.99→ $43.99
- 2 certificates verified at the lab10mg$25.00→ $20.00
- 1 certificate verified at the lab10mg$44.99$26.99→ $24.29
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Technical Specifications
- Peptide Class
- Synthetic pentapeptide GHS-R agonist
- Molecular Weight
- 711.85 Da
- Receptor Target
- GHS-R1a (ghrelin receptor)
- Key Selectivity
- GH-specific; minimal cortisol/prolactin elevation
- Available Sizes
- 10mg vials
- Form
- Lyophilized powder
- Purity
- ≥99% (third-party tested)
Legal Status
Research Chemical
View full legal status guide →
Known Interactions
8 documented interactions for Ipamorelin
MK-677Caution
Both stimulate GH secretion via ghrelin receptor. Combining may cause excessive GH/IGF-1 elevation. Use lower doses if combining.
Emerging evidence
CJC-1295Synergistic
CJC-1295 (GHRH analog) + Ipamorelin (ghrelin mimetic) is the gold-standard GH-releasing combination. Dual-pathway stimulation produces amplified, pulsatile GH release.
Clinical evidence
Stacking guide →SermorelinSynergistic
Both stimulate GH release via complementary pathways. Commonly co-administered in anti-aging protocols.
Emerging evidence
IGF-1 LR3Synergistic
Ipamorelin stimulates endogenous GH; IGF-1 LR3 provides direct anabolic signaling downstream. Complementary anabolic stack.
Emerging evidence
BPC-157Neutral
Commonly co-administered in clinical settings for recovery. Different primary targets — no known negative interaction.
Emerging evidence
Interaction data is based on published research, known pharmacological mechanisms, and clinical practitioner experience. Evidence tiers: Clinical = human data; Emerging = preclinical/case reports; Theoretical = mechanism-based inference. Always consult a qualified healthcare provider before combining compounds.
Interaction Guides
Source Ipamorelin at Purgo Labs
10mg $54.99 list · $43.99 with code HEALTH · lab-verifiable COA per lot
Vendor Scoreboard — top 3 by verified evidenceVerified 1 November 2026
Related Research
Other Compounds in This Guide
Safety
Ipamorelin side effects
Human trial dataLimited human trial data (phase 1/2 for postoperative ileus); not approved
Ipamorelin was taken into human trials for postoperative bowel recovery, where it was reported as well tolerated with an adverse-event profile similar to placebo over short courses. It is a selective GH secretagogue, so the expected effects are those of a GH pulse: transient water retention, tingling, and changes in glucose handling. Long-term data do not exist.
Research-use information only. Research-grade Ipamorelin is not an approved medicine; where trial or label figures appear below they belong to the pharmaceutical product studied, not to any research vial. This section does not give dosing or medical advice.
What is reported
Every rate carries its source. Where no source exists, no rate is printed.
| Effect | Rate (sourced) | Detail | Source |
|---|---|---|---|
| Short-course tolerability | not quantified | Adverse events comparable to placebo in the phase 2 ileus programme. | Beck et al. 2014 |
| GH-pulse effects (water retention, paraesthesia, headache) | not quantified | Class effects of GH secretagogues; not quantified for ipamorelin in long-term use. | Class pharmacology |
What is not known
- •Effects of long-term repeated dosing.
- •Research-grade identity and dose.
Mechanism-based cautions
- •GH/IGF-1 axis: theoretical malignancy caution; monitor glucose in anyone with insulin resistance.
- •Selective for GH over cortisol/prolactin compared with GHRP-2/6 — a real advantage in the class, not an absence of effects.
Regulatory status: Not approved anywhere; development for ileus discontinued.
Side-effect references
- Beck DE, et al. Ipamorelin, a novel ghrelin mimetic, in postoperative ileus. Neurogastroenterology & Motility, 2014.
What is actually in a research vial
Everything above describes Ipamorelin the molecule. The risk specific to a research vial is different: it may not contain Ipamorelin at the labelled amount, and it may contain what the synthesis left behind. Identity (mass spectrometry), purity (HPLC), measured net content and an endotoxin result are the four lines on a certificate that bear on adverse effects, and only a certificate you can check at the laboratory tells you any of them. This is what we have verified for Ipamorelin so far.
Who sells Ipamorelin, and what they document
39 of the 105 vendors on our scoreboard list Ipamorelin with a price we read on the product page (11 Sep 2026–1 Nov 2026). Of those, 32 name their testing laboratory, 27 publish certificates that resolve on the lab's own site, and 30 publish measured milligrams against the label. The full ranking, with every dated price, is on Best Ipamorelin Vendors.
| Vendor | Rubric | Lab named | Price read |
|---|---|---|---|
| MyPurePeptidepartner | 10/10 | Janoshik Analytical | $25.00 · 10mg · 1 Nov 2026 |
| Oneday Compoundspartner | 10/10 | ILS Laboratories (San Diego, CA) | $26.99 · 10mg · 29 Oct 2026 |
| Peptide Giantspartner | 10/10 | Janoshik Analytical · Vanguard Laboratory | $26.00 · 5mg · 1 Nov 2026 |
| Purgo Labspartner | 10/10 | SteriGenix · Freedom Diagnostics | $54.99 · 10mg · 1 Nov 2026 |
| Amino Clubpartner | 9/10 | ILS Labs | $49.99 · 10mg · 2 Oct 2026 |
Top 5 by rubric score; 34 more on the ranking page.
Ipamorelin certificates we have opened
None yet for Ipamorelin specifically. The COA library holds the certificates we have read for each vendor on other compounds, which is the next best signal of how that vendor documents a lot.
Side-effect questions
Side-effect section last reviewed 2026-09-12. Moved from the standalone side-effects page on 10 October 2026; text unchanged.
Regulatory
Is Ipamorelin legal?
Legal as a research chemicalIpamorelin is legal to purchase and possess in the United States as a research chemical. It is not a controlled substance under the DEA Controlled Substances Act and is not FDA-approved for human use.
US Status
Research Chemical
Legal to purchase for research
DEA Schedule
Not Scheduled
Not a controlled substance
FDA Status
Not Approved
Not FDA-approved for human use
Status by country
| Jurisdiction | Status as stated |
|---|---|
| United States | Legal as a research chemical. Not a scheduled substance. Not FDA-approved for human use. The FDA has restricted its use in compounded preparations. |
| Canada | Not a scheduled substance. Available for research purposes. Not approved by Health Canada. |
| United Kingdom | Not listed under the Misuse of Drugs Act. Available for research purposes. |
| Australia | Not currently scheduled by the TGA. Available for research purposes. |
| European Union | Generally available for research purposes. Not approved as a medicinal product by the EMA. |
Statements above are as our legal-status page for Ipamorelin stated them in 2025; they were moved here on 10 October 2026 and were not re-verified in the move. Regulations change. This is general information, not legal advice; check the current position with your own jurisdiction's regulator before relying on it.
Legal questions
Is ipamorelin a controlled substance?
No. Ipamorelin is not listed as a controlled substance under the US DEA Controlled Substances Act.
Can I buy ipamorelin legally in the US?
Yes. Ipamorelin can be legally purchased as a research chemical in the United States for legitimate laboratory research purposes.
Is ipamorelin banned in sports?
Yes. Ipamorelin is prohibited by WADA as a growth hormone secretagogue under the category of peptide hormones and related substances.
Did the FDA ban ipamorelin?
The FDA has not banned ipamorelin outright but has restricted its use in compounded preparations, citing lack of clinical evidence for safety and efficacy in humans.
Is ipamorelin the same as CJC-1295?
No. Ipamorelin is a ghrelin receptor agonist (GHRP), while CJC-1295 is a GHRH analogue. They work via different receptors and are often combined in research protocols.
Research Guides
Related Research Guides
Everything we publish on Ipamorelin
More on Ipamorelin: comparisons, interactions, where to buy
- CJC-1295 + Ipamorelin Research: The Science Behind the Most Popular Peptide Stack (2026)
- Ipamorelin Research Guide (2026): Mechanism, Dosage & Clinical Evidence
- Ipamorelin and CJC-1295 — Interaction Research Guide
- Ipamorelin vs GHRP-2 vs GHRP-6 — Research Comparison
- Sermorelin vs Ipamorelin — Research Comparison
Supporting Research
Preclinical OnlyPreclinical Only (animal/in vitro — no human RCTs for ipamorelin)
Evidence note: No completed human clinical trials exist for ipamorelin. Human GH secretagogue data (e.g., MK-677 studies) shares the receptor mechanism but cannot be directly extrapolated to ipamorelin.
Ipamorelin's selectivity profile (GH release without cortisol/prolactin elevation) is established in preclinical studies. No human RCTs have been published for ipamorelin specifically. Human data on GH secretagogues generally comes from MK-677 (oral GHS-R1a agonist) studies, which share the receptor mechanism but are not the same compound.
References
- Raun K, et al.ANIMAL STUDY (rat)Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998. PubMedIpamorelin selectively stimulates GH release without affecting cortisol, prolactin, or ACTH — establishing its selectivity profile.
- Johansen PB, et al.ANIMAL STUDY (rat)Ipamorelin, a new growth-hormone-releasing peptide, induces longitudinal bone growth in rats. Growth Horm IGF Res. 1999. PubMedIpamorelin stimulated longitudinal bone growth in rodent models comparable to GHRP-6 without side effects.
Research Databases
PubMed
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