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, with little effect on cortisol or prolactin, the side effects that older growth hormone releasers tend to cause. It's often paired with CJC-1295, a different type of growth hormone releaser, for a stronger combined effect. It's not FDA-approved (the company that developed it ended its trials after it failed to beat a placebo for an unrelated surgery-recovery use), 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. Studies showed it reliably produces a short pulse of growth hormone with little effect on cortisol or prolactin — the main reason it's preferred over older peptides in its class. It was tested in humans for gut-motility recovery after surgery but did not outperform placebo, so development stopped. 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 Prohibited List 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. ✓ verified 2026-07-18 against the archived 2026 list. 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 a Helsinn Therapeutics-sponsored Phase 2 postoperative-ileus trial (NCT00672074) completed December 2009 and published 2014 did not beat placebo, ending development. 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.

⚠️ For research and educational purposes only. 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 (typically 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 what underlies Ipamorelin's synergy when stacked with GHRH analogs like CJC-1295: GHRH analogs and GHRPs activate different receptors that both lead to GH release, and the combined activation produces greater GH output than either alone.

The selectivity advantage. Ipamorelin's defining pharmacological property — and the reason it is preferred over older GHRPs in research-community use — is its selective action on GHS-R1a without significant stimulation of cortisol or prolactin release. Earlier-generation GHRPs (GHRP-2, GHRP-6, hexarelin) all produce dose-dependent elevations in cortisol and prolactin alongside their GH-releasing effects, with potential downstream consequences (cortisol → catabolic state, prolactin → various endocrine effects).[¹][²] Ipamorelin, in contrast, was specifically designed and selected during the Novo Nordisk discovery program for its lack of cortisol and prolactin stimulation at GH-stimulating doses. This is the single most important reason researchers choose Ipamorelin over older GHRPs.

Clinical development history. Novo Nordisk discovered Ipamorelin in 1998 (development code NNC 26-0161) and advanced it through early clinical pharmacology work. The compound was later licensed, and the most prominent 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. That trial (NCT00672074) completed December 2009 and was published in 2014;[⁴] it did not demonstrate sufficient efficacy over placebo (primary endpoint p=0.15, not significant), and development was not pursued further.

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 GHRH analog (CJC) + GHRP (Ipamorelin) act on different receptors and produce synergistic GH release. The CJC-1295 no-DAC + Ipamorelin pairing is one of the most common research-peptide stacks; see [cjc-1295.md](./cjc-1295.md) for the GHRH-side detail and `cjc-1295-ipamorelin-blend.md` when published for the combined-product entry.

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 — Ipamorelin's defining selectivity is the absence of significant cortisol stimulation at GH-effective doses, distinguishing it from GHRP-2, GHRP-6, and hexarelin.[¹]
• Prolactin elevation — same selectivity story.
• Same theoretical concerns as CJC-1295 — see [cjc-1295.md](./cjc-1295.md) Side Effects section 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 cortisol/prolactin issues that Ipamorelin was selected to avoid

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 · NCT00672074)

• 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