Ipamorelin

Ipamorelin is a growth hormone releaser known as one of the more selective options in its class: it triggers a short pulse of the body's own growth hormone by acting on the ghrelin (hunger hormone) receptor. In animal studies it did this without raising cortisol, a stress hormone that older growth hormone releasers push up; that difference hasn't been clearly shown in people. It's often paired with CJC-1295, a growth hormone releaser that works through a different pathway, on the idea that using both pathways at once adds up. There's little controlled human evidence for that so far. It's not FDA-approved: its only trials in patients were for an unrelated surgery-recovery use, where the first did not beat a placebo and the second never reported results. There are no brand-name products, and it's banned in drug-tested sport.

Ipamorelin has been studied as a selective way to trigger growth-hormone release. A small study in healthy men found it produces a single short pulse of growth hormone that peaks within about an hour. In animal studies it did not raise cortisol the way older peptides in its class do, which is the main reason it's preferred over them; that difference hasn't been clearly shown in people. It was tested in people recovering from bowel surgery, to see whether it sped up gut recovery: the first trial found no benefit over placebo, and a second, larger trial finished without reporting results. The body-composition, sleep, and recovery uses people pursue come from its pharmacology plus user reports, not confirmed clinical trials.

WADA-banned in regulated sport — ipamorelin is explicitly named in the WADA 2026 and 2027 Prohibited Lists[⁸] under S2.2.4 (Growth Hormone Releasing Factors → growth hormone secretagogues / GHS), alongside anamorelin, capromorelin, ibutamoren (MK-677), lenomorelin (ghrelin), and macimorelin, prohibited at all times. Not DEA-scheduled. Not FDA approved for any indication. Novo Nordisk discovered ipamorelin (1998, development code NNC 26-0161); the compound was later licensed, and Helsinn Therapeutics sponsored two placebo-controlled Phase 2 postoperative-ileus trials: the first (NCT00672074, completed December 2009, published 2014) did not beat placebo, and the second, larger one (NCT01280344, completed May 2014) has no posted or published results. No later interventional trial is registered. Currently sold as a research peptide. On the FDA 503A Category 2 bulk-substances list since the September 2023 action; exact current-year 503A/503B sub-status.

Ipamorelin is not FDA-approved and is banned in regulated sport. VialWise is a research and educational reference, not medical advice — consult a licensed professional before considering any compound.

⚠️ Ipamorelin is not approved by the FDA for any indication. Information in this entry is informational, not medical advice. Always confirm dose calculations with the in-app calculator and consult appropriate professional guidance before any protocol decisions.

⚠️ Precision matters at low doses. Ipamorelin is dosed in micrograms ( per dose), placing typical draws in the range depending on reconstitution. Small dosing errors that look trivial in absolute terms can be significant in percentage terms when starting doses are small. A one-unit mis-draw at a 5-unit dose is a 20% error; the same one-unit error at a 30-unit dose is only 3.3%. Always verify draws against the in-app calculator and double-check the unit count on the syringe before injecting — most acutely at the smallest draws in your titration.

Ipamorelin is a pentapeptide (five-amino-acid) growth hormone-releasing peptide (GHRP) discovered and originally developed by Novo Nordisk under the development code NNC 26-0161.[¹] The molecule binds to the ghrelin receptor (also called GHS-R1a — the growth hormone secretagogue receptor type 1a) at the pituitary, stimulating growth hormone release through a receptor pathway distinct from that used by growth-hormone-releasing hormone (GHRH). This receptor-pathway distinction is the rationale for stacking it with GHRH analogs like CJC-1295: GHRH analogs and GHRPs activate different receptors that both lead to GH release, so combining them is expected to release more GH than either alone. For this pairing, that expectation has little controlled human evidence behind it (see Stacking with CJC-1295 below).

The selectivity advantage. Ipamorelin's defining pharmacological property — and the reason it is preferred over older GHRPs in research-community use — is that, in animal studies, it released growth hormone without the cortisol rise those older peptides cause. In people, earlier-generation GHRPs (GHRP-2, GHRP-6, hexarelin) raise cortisol, and more variably prolactin, alongside their GH-releasing effects, with potential downstream consequences (cortisol → catabolic state, prolactin → various endocrine effects).[²][⁶] That evidence comes from the discovery paper's swine studies: GHRP-6 and GHRP-2 raised ACTH and cortisol, while ipamorelin did not, even at doses more than 200-fold above its half-maximal GH dose. The authors called that result "very surprising", so it was a finding of the chemistry program rather than its design goal. Prolactin did not change with any of the peptides tested in that study, so it shows no prolactin difference.[¹] In people, a 2026 review reports no significant effect on other pituitary or adrenal hormones in an early healthy-volunteer study,[⁶] but that study's published summary reports growth hormone only,[⁹] so the human side of the comparison is not well documented. This selectivity is still the main reason researchers choose Ipamorelin over older GHRPs.

Clinical development history. Novo Nordisk discovered Ipamorelin in 1998 (development code NNC 26-0161). Early human pharmacology work includes a dose-escalation study in healthy male volunteers that characterized its pharmacokinetics and GH response.[⁹] The compound was later licensed, and its Phase 2 program — targeting postoperative ileus (gastrointestinal motility recovery after surgery, where gut prokinetic effects of GHS-R1a agonism were the rationale) — was sponsored by Helsinn Therapeutics (U.S.), Inc. The first trial (NCT00672074) completed December 2009 and was published in 2014;[⁴] it did not demonstrate efficacy over placebo (primary endpoint p=0.15, not significant). Helsinn then ran a second, larger placebo-controlled, dose-finding Phase 2 trial (NCT01280344), which started in April 2011, after the first had ended, enrolled 320 patients and completed in May 2014. It has no results posted on ClinicalTrials.gov, and no publication of it has been found.[¹⁰] No later interventional trial of ipamorelin is registered.

Current research-community use. Despite the absence of FDA approval, Ipamorelin is widely used in the research-peptide community for: - Body composition optimization (lean mass, fat mass), typically as part of a stack with CJC-1295 no-DAC - Sleep quality (particularly when dosed at bedtime, amplifying the natural sleep-time GH pulse) - Recovery from training - General "anti-aging" / IGF-1 elevation contexts

These uses are based on extrapolation from clinical pharmacology data plus accumulated researcher experience. Ipamorelin has no FDA-approved indication.

Stacking with CJC-1295. Ipamorelin is most commonly stacked with CJC-1295 — usually the no-DAC formulation (Mod GRF 1-29) — on the rationale that a GHRH analog (CJC) and a GHRP (Ipamorelin) act on different receptors, so together they should release more GH than either alone. A 2026 review describes the pairing as a way "to amplify GH release through complementary stimulation of the GH axis", but says "this practice is largely driven by anecdotal rationale, and controlled clinical evidence supporting synergy or meaningful body-composition outcomes in healthy individuals remains limited."[⁶] The pair's reported muscle result comes from animals: a 2026 sports-medicine review reports improved maximum tetanic tension (muscle force) in mouse models of glucocorticoid-induced muscle loss and notes "these findings are limited to animal studies."[⁷] The CJC-1295 no-DAC + Ipamorelin pairing is one of the most common research-peptide stacks; see the CJC-1295 entry for the GHRH-side detail and the CJC-1295 / Ipamorelin Blend entry for the combined product.

Commonly reported

• Acute flushing, lightheadedness, tingling — transient, related to the acute GH pulse. The most-reported side effect in research-community use of the CJC/Ipa stack.
• Hunger increase — the ghrelin receptor is the body's primary "hunger" receptor; activating it (which is what Ipamorelin does at the GHS-R1a target) produces appetite stimulation as an on-mechanism side effect. This is the most reliable subjective sign of Ipamorelin activity and the main "feature that can be a bug" depending on the researcher's goals.
• Headache — uncommon
• Mild water retention — particularly during the first 1–2 weeks of a cycle
• Sleep changes — usually improved deep sleep when dosed at bedtime; this is one of the most-reported subjective benefits
• Cortisol elevation — not typically reported. In the discovery paper's animal studies it did not occur, even at very high doses, while GHRP-2 and GHRP-6 raised cortisol.[¹] In people it is not well documented: a 2026 review reports no effect in an early human study,[⁶] but that study's published summary reports growth hormone only.[⁹]
• Prolactin elevation — not typically reported. Older GHRPs raise it variably in people.[⁶] The discovery paper's animal study found no prolactin change with any peptide tested, so it shows no difference;[¹] human data for ipamorelin are as thin as for cortisol.
• Same theoretical concerns as CJC-1295 — see the Side Effects section of the CJC-1295 entry for: insulin resistance / impaired glucose tolerance, IGF-1-mediated theoretical cancer concerns, theoretical cardiovascular concerns from sustained GH/IGF-1 elevation. These are class-level concerns for any GH-elevating intervention; specific data on long-term Ipamorelin use is essentially absent.

Active malignancy or undiagnosed cancer concern — theoretical contraindication based on IGF-1 elevation. Class consideration for any GH-elevating intervention.

Diabetes or impaired glucose tolerance — caution due to GH's counter-regulatory effects on insulin sensitivity

Pregnancy and lactation: no data; default to contraindicated

Pediatric use: no data — should not be used in researchers under 18; GH-elevating interventions in children are heavily regulated and require specialist medical supervision

Concurrent use of exogenous GH — combined GH elevation is unpredictable; not studied

Concurrent use of another GHRP — receptor saturation + reintroduces the cortisol and prolactin effects of older GHRPs, which researchers describe as the reason they choose Ipamorelin

Hyperinsulinism caution

Regulatory note (US): Ipamorelin was placed on the FDA 503A Category 2 bulk-substances list in the September 2023 action (the same action that caught BPC-157), which halts legal 503A compounding pending review. The exact current-year 503A/503B sub-status.

Growth hormone secretagogue

A compound that signals the body to release its own growth hormone, rather than supplying growth hormone directly.

Pituitary gland

A small gland at the base of the brain that releases growth hormone and other hormones.

Subcutaneous

An injection into the fatty layer just under the skin, rather than into a muscle or vein.

WADA Prohibited List

The list of substances banned in regulated sport by the World Anti-Doping Agency.

1. Raun K, Hansen BS, Johansen NL, Thøgersen H, Madsen K, Ankersen M, Andersen PH. (1998). Ipamorelin, the first selective growth hormone secretagogue. European Journal of Endocrinology, 139(5):552–561.(PMID 9849822)
2. Sigalos JT, Pastuszak AW. (2018). The Safety and Efficacy of Growth Hormone Secretagogues. Sexual Medicine Reviews, 6(1):45–53.(PMID 28400207)
3. Bowers CY. (2001). Unnatural growth hormone-releasing peptide begets natural ghrelin. Journal of Clinical Endocrinology and Metabolism, 86(4):1464–1469.(PMID 11297568)
4. Beck DE, Sweeney WB, McCarter MD, Ipamorelin 201 Study Group. (2014). Prospective, randomized, controlled, proof-of-concept study of the Ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients. International Journal of Colorectal Disease, 29(12):1527–1534.(PMID 25331030 · NCT00672074)
5. Ankersen M, Johansen NL, Madsen K, Hansen BS, Raun K, Nielsen KK, Thøgersen H, Hansen TK, Peschke B, Lau J, Lundt BF, Andersen PH. (1998). A new series of highly potent growth hormone-releasing peptides derived from ipamorelin. Journal of Medicinal Chemistry, 41(19):3699–3704.(PMID 9733495)
6. Dominikowski A, Rękoś Z, Olejarz M, Szczepanek-Parulska E, Domin R, Ruchała M. (2026). The emerging landscape of performance-enhancing peptides modulating GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration. Frontiers in Endocrinology, 17:1822475.(PMID 42395176)
7. Mayfield CK, Bolia IK, Feingold CL, Lin EH, Liu JN, Rick Hatch GF, Gamradt SC, Weber AE. (2026). Injectable Peptide Therapy: A Primer for Orthopaedic and Sports Medicine Physicians. The American Journal of Sports Medicine, 54(1):223–229.(PMID 41476424)
8. World Anti-Doping Agency. World Anti-Doping Code International Standard Prohibited List 2027 (effective 1 January 2027). PDF: wada-ama.org/sites/default/files/2026-09/2027list_en_final_clean_26_august_2026_2.pdf. Ipamorelin is named under S2.2.4 (growth hormone secretagogues): "ipamorelin".
9. Gobburu JV, Agersø H, Jusko WJ, Ynddal L. (1999). Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharmaceutical Research, 16(9):1412–1416.(PMID 10496658)
10. Helsinn Therapeutics (U.S.), Inc. Phase II Double-Blind Placebo-Controlled Dose Finding Study to Evaluate Safety/Efficacy of Ipamorelin Compared to Placebo for Recovery of Gastrointestinal Function in Patients Following Small or Large Bowel Resection w/Primary Anastomosis. ClinicalTrials.gov: NCT01280344. Phase 2 (sponsor study ID HT-IPAM-202); randomized, quadruple-masked, placebo-controlled, three ipamorelin arms. Status: COMPLETED; start 2011-04; primary completion 2013-06; completion 2014-05; enrollment 320 (actual). No results posted and no linked publication; a PubMed search for the registry ID returns 0.(NCT01280344)

• CJC-1295 — discussed together in this entry's stacks section
• BPC-157 / TB-500 Blend — discussed together in this entry's stacks section
• CJC-1295 / Ipamorelin Blend — same mechanism class
• GHRP-2 — same mechanism class
• GHRP-6 — same mechanism class
• Hexarelin — same mechanism class