Ipamorelin
A selective growth hormone secretagogue that stimulates GH release without significantly affecting cortisol or prolactin.
What is Ipamorelin?
Ipamorelin is a pentapeptide (five amino acids) that selectively stimulates growth hormone release from the pituitary gland. What makes it notable is its selectivity — unlike some other GH secretagogues, it does not significantly increase cortisol, prolactin, or aldosterone levels. This selectivity is why it is considered one of the most well-tolerated peptides in the growth hormone category.
What Ipamorelin Is Investigated For
Ipamorelin is investigated for GH-mediated body composition improvement, sleep quality, and recovery, and is often discussed in the context of the CJC-1295 + ipamorelin stack that dual-activates the GHRH and ghrelin receptor pathways. The strongest evidence is for its defining selectivity profile — established clinical PK/PD work (Raun et al., 1998) shows it releases GH without the ACTH, cortisol, prolactin, or aldosterone elevation seen with GHRP-6 or hexarelin, even at doses 200-fold above effective GH-releasing levels. A Phase IIb RCT in postoperative ileus showed a trend toward faster GI recovery but did not advance to Phase III, and ipamorelin is not FDA-approved for any indication. Downstream outcomes — body composition, lean-mass gain, sleep improvement, recovery — are plausible from GH/IGF-1 pharmacology but have never been tested in long-duration human endpoint trials. The best honest framing is 'cleanest of the GHRPs on side-effect profile, but without definitive clinical efficacy data for anti-aging or performance use.'
History & Discovery
Ipamorelin was developed at Novo Nordisk in the late 1990s and first reported in the peer-reviewed literature in 1998 (Raun et al., European Journal of Endocrinology). It emerged from a medicinal-chemistry program aimed at improving on the earlier growth hormone-releasing peptides (GHRP-6, GHRP-2, hexarelin) by stripping away the off-target hormonal effects — particularly cortisol, ACTH, and prolactin elevation — that limited the older compounds. Novo Nordisk screened a series of pentapeptides and identified the Aib-His-D-2-Nal-D-Phe-Lys-NH2 sequence as retaining potent ghrelin-receptor agonism while demonstrating remarkable selectivity: even at doses 200-fold above the effective GH-releasing dose, it did not significantly raise ACTH, cortisol, or prolactin in the original pig and rat studies. Novo Nordisk progressed ipamorelin into early human trials but ultimately did not advance it toward an approved indication; the compound was later licensed to Helsinn Therapeutics, which ran a Phase IIb proof-of-concept trial in postoperative ileus (published 2014) that showed a trend toward faster GI recovery but did not move to Phase III. No approved therapeutic indication has materialized. Like CJC-1295, ipamorelin migrated into the research-chemical and compounding-pharmacy channel during the 2010s, where it became one of the most commonly discussed peptides in the GH-optimization space — largely on the strength of its selectivity profile and the 'cleanest of the GHRPs' reputation it earned in the preclinical literature.
How It Works
Ipamorelin works by mimicking ghrelin, a natural hunger hormone that also triggers growth hormone release. However, it is designed to be very selective — it tells the pituitary to release GH without triggering other hormonal responses that could cause unwanted side effects.
Ipamorelin is a pentapeptide ghrelin mimetic that binds to the GHS-R1a (growth hormone secretagogue receptor) in the pituitary gland. Unlike GHRP-6 and GHRP-2, it demonstrates high selectivity for GH release without dose-dependent increases in ACTH, cortisol, prolactin, or aldosterone. It acts synergistically with GHRH, which is why it is commonly paired with CJC-1295. The GH release follows a bell-shaped dose-response curve, and it preserves the natural pulsatile pattern of GH secretion.
Evidence Snapshot
Human Clinical Evidence
Moderate. Human pharmacokinetic and pharmacodynamic studies exist. Clinical trials have demonstrated GH-releasing efficacy.
Animal / Preclinical
Strong. Well-characterized selectivity profile in multiple animal models.
Mechanistic Rationale
Strong. GHS-R1a receptor pharmacology is well understood.
Research Gaps & Open Questions
What the current literature has not yet settled about Ipamorelin:
- 01Long-term (>12 month) human safety and efficacy data in healthy adults is absent — ipamorelin has no completed late-stage human program at any indication.
- 02Whether the superior selectivity profile observed preclinically (no ACTH, cortisol, prolactin elevation) translates into a meaningfully better long-term human safety margin vs. older GHRPs has not been directly tested in long-duration trials.
- 03Head-to-head clinical comparison of ipamorelin monotherapy vs. ipamorelin + GHRH-analog stacks — the stacking argument is pharmacological rather than outcome-validated in controlled human endpoint data.
- 04Optimal cycling cadence vs. continuous dosing has not been studied; tachyphylaxis risk at the ghrelin receptor with chronic exposure is theoretical rather than quantified.
- 05IGF-1 elevation magnitude and downstream cancer-promotion risk specific to ipamorelin has not been characterized in long-term human pharmacovigilance.
- 06Postoperative ileus and cachexia indications have promising signals from smaller trials but no definitive Phase III data exists.
Forms & Administration
Ipamorelin is administered via subcutaneous injection, typically in the evening before bed to align with natural GH release patterns. Protocols should be determined by a qualified clinician.
Dosing & Protocols
The ranges below reflect protocols commonly discussed in the literature and by clinicians — not a prescription. Actual dosing for any individual should be determined by a qualified healthcare provider who knows the patient.
Typical Range
Protocols commonly discussed for ipamorelin run 200–300 mcg per dose, administered 1–3 times daily. The most conservative protocols use 200 mcg once daily at bedtime; more aggressive body-composition protocols use 300 mcg three times daily (morning, pre-workout or midday, bedtime). Total daily doses above ~1 mg produce diminishing returns because the GH response curve is bell-shaped — higher single doses do not produce proportionally greater GH release and may shift the response curve downward.
Frequency
Ipamorelin is short-acting (serum half-life ~2 hours), so frequent dosing produces multiple discrete GH pulses per day. The standard stacking rationale with a GHRH analog like CJC-1295 or sermorelin rests on two distinct receptor pathways: ipamorelin acts at the ghrelin/GHS-R1a receptor on somatotrophs, while GHRH analogs act at the GHRH receptor. Combined, the two produce a GH pulse that is substantially greater than either alone — this is a synergistic rather than additive effect, because the GHRH component increases somatotroph readiness while the GHRP component triggers the release. This dual-pathway rationale is the basis for nearly every 'ipamorelin + CJC' protocol in circulation.
Timing Considerations
Time of day
Bedtime is the most common window, aligned with the natural nocturnal GH pulse; multi-dose protocols typically add a mid-morning fasted dose and a pre-workout dose.
Relative to meals
Fasted — at least 30 minutes before food and 2+ hours after a meal. Elevated insulin and circulating amino acids substantially blunt GH release, so meal timing directly affects pulse amplitude.
Relative to exercise
Independent of training, though some users add a pre-workout dose on training days for an additional GH pulse around exercise.
Cycle Length
Commonly discussed protocols run 8–12 weeks on, followed by a 4-week off period. Continuous use is also discussed in wellness contexts; pituitary desensitization is a theoretical concern with sustained ghrelin-receptor agonism, though ipamorelin's selectivity and relatively short receptor occupancy make tachyphylaxis less of a documented issue than with older GHRPs. No human trial has directly compared continuous vs. cycled dosing.
Protocol Notes
Ipamorelin is supplied as a lyophilized powder — typically 2 mg or 5 mg per vial — reconstituted in bacteriostatic water. A 5 mg vial in 2 mL of BAC water yields 2,500 mcg/mL, making 250 mcg roughly 0.1 mL or 10 units on an insulin syringe. Subcutaneous injection into the abdominal fat pad is the standard route. Because ipamorelin acts at the ghrelin receptor, dosing on a relatively empty stomach matters: circulating amino acids and elevated insulin blunt GH release, so most protocols call for injection at least 30 minutes before eating or 2+ hours after a meal. Bedtime dosing is popular because it aligns with the natural nocturnal GH pulse and can enhance slow-wave sleep in users. When stacked with CJC-1295 no-DAC or sermorelin, both peptides are typically drawn into the same syringe and injected together at each dosing window.
Ipamorelin is not FDA-approved for any indication. The numbers above describe commonly-referenced protocols, not a prescription. Use should be supervised by a qualified clinician with appropriate IGF-1 and metabolic monitoring.
Timeline of Effects
Onset
Sleep-quality improvements — particularly deeper and more restorative slow-wave sleep — are the most commonly reported early signal, often within the first 1–2 weeks of bedtime dosing. Subjective recovery benefits (less post-workout soreness, faster return to training) follow in a similar window. Body-composition changes — modest fat mass reduction, lean mass preservation or gain — typically require 4–8+ weeks of consistent use before becoming visible.
Peak Effect
Serum IGF-1 increases progressively over the first month of daily dosing and tends to plateau; GH pulse amplitude is elevated from the first dose but the downstream IGF-1 accumulation takes weeks. Subjective benefits most commonly plateau around the 3-month mark. Ipamorelin's effect size on IGF-1 is typically modest compared to MK-677 or high-dose CJC-1295 DAC — it is characterized more by its clean side-effect profile than by maximum IGF-1 elevation.
After Discontinuation
Short half-life and no suppression of endogenous GHRH mean endogenous pulsatile GH secretion returns to baseline within days of discontinuation. IGF-1 drifts back to pre-treatment levels over 2–4 weeks. Any accumulated body-composition or sleep benefits wane over weeks to months depending on the underlying reason for the benefit (e.g., sleep improvement tends to regress faster than lean-mass gains). No post-cycle therapy is required, as ipamorelin does not suppress the HPG axis.
Monitoring & Measurement
Bloodwork & Labs
- •IGF-1 (serum) — the primary response marker; the GH pulse itself is too short to catch reliably in routine labs, so IGF-1 is the practical proxy
- •Fasting glucose and HbA1c — GH secretagogues can mildly raise both
- •Lipid panel — visceral-fat-driven changes show here first
- •Prolactin and cortisol — expected to stay flat on a selective GHRP like ipamorelin; if either rises, suspect a non-selective or contaminated batch
Functional & Performance Tests
- •DEXA scan — lean mass and visceral fat are the endpoints that matter
- •Waist circumference
- •Grip strength (dynamometer)
- •Overnight sleep quality via wearable (Oura, Whoop, Apple Watch) — sleep depth is a frequently reported effect
When to Test
Baseline, 6 weeks, and 12 weeks on-cycle.
Interpretation & Notes
A 20–40% IGF-1 rise within 6–8 weeks is a typical responder signal. Fasting glucose may drift up 5–15 mg/dL — tolerable, but if it crosses 100 mg/dL or HbA1c reaches 5.7, pull the dose back. Ipamorelin's defining feature is selectivity: unlike GHRP-6 or hexarelin, it should not move prolactin or cortisol. A prolactin doubling on ipamorelin means either a dose too high, a non-selective contaminant, or a mislabeled vial — a useful quality signal for unregulated market sourcing. Standard IGF-1 and metabolic panels are direct-to-consumer via LabCorp, Quest, Marek Health, and Ulta Lab Tests; interpret with a clinician.
Common Questions
Who Ipamorelin Is NOT For
- •Active or recent-history cancer — GH and IGF-1 elevation may accelerate proliferation of existing malignancies; clinicians exclude active cancer from secretagogue protocols.
- •Pregnancy — no human pregnancy safety data; reproductive-toxicology characterization is absent.
- •Breastfeeding — no data on transfer into breast milk or effects on nursing infants.
- •Diabetes or uncontrolled insulin resistance — GH opposes insulin action; ipamorelin's GH effect is milder than MK-677's but glycemic monitoring remains prudent.
- •Pediatric use outside a diagnosed GH deficiency — development-related endocrine effects from unmonitored secretagogue use are a concern.
- •Active acromegaly or pituitary adenoma — further stimulation of GH-producing cells is contraindicated.
- •Uncontrolled hypertension or moderate-to-severe sleep apnea — GH elevation can worsen fluid retention and upper-airway edema, though ipamorelin's milder water-retention profile makes this less prominent than with rhGH.
- •Known hypersensitivity to peptide therapeutics or to excipients in compounded preparations.
Drug & Supplement Interactions
Documented clinical drug interactions for ipamorelin are sparse, as no post-marketing surveillance exists. Theoretical concerns track the GH-secretagogue class. Glucose-regulating medications: insulin, sulfonylureas, and GLP-1 agonists may require dose adjustment as GH/IGF-1 rise, because GH opposes insulin action. Ipamorelin's effect is milder than MK-677's but is not zero over weeks of use. Corticosteroids (prednisone, dexamethasone) blunt somatotroph responsiveness and can attenuate ipamorelin's GH-releasing effect at the pituitary level. Thyroid hormone status matters — uncorrected hypothyroidism reduces GH response. Somatostatin analogs (octreotide, lanreotide) directly antagonize GH release and will pharmacologically oppose ipamorelin. Opioids have complex interactions with the ghrelin/GHS-R axis — chronic opioid use can alter ghrelin tone and potentially modulate ipamorelin response, though this is not well characterized in humans. Oral estrogens reduce hepatic IGF-1 generation and can affect interpretation of IGF-1 labs. SSRIs and other serotonergic agents have been implicated in ghrelin-pathway modulation in some preclinical work, but clinical significance for ipamorelin specifically is unclear. Disclose all concurrent medications to the prescribing clinician.
Safety Profile
Common Side Effects
Cautions
- • Not FDA-approved
- • Should be monitored with blood work
- • Not appropriate for those with active malignancies
What We Don't Know
Long-term safety data from large clinical trials is not available. Optimal cycle length and long-term effects are not well established.
Legal Status
United States
Ipamorelin is not FDA-approved for any medical indication. Its US compounding-pharmacy access has narrowed through a multi-year regulatory review: the FDA's Pharmacy Compounding Advisory Committee (PCAC) voted against adding ipamorelin to the 503A Bulks List in October 2024 citing insufficient efficacy evidence and safety concerns (fluid retention, congestive-heart-failure signal, hyperglycemia). On April 15, 2026, HHS Secretary Kennedy directed the FDA to remove 12 peptides from Category 2 (bulk drug substances presenting significant safety risks) — but ipamorelin was deliberately excluded from that action. It will be re-reviewed at the July 23–24, 2026 PCAC meeting alongside CJC-1295, AOD-9604, and thymosin alpha-1. As of April 2026, legitimate clinical access remains restricted while reconsideration is pending. Research-chemical vendors continue to sell ipamorelin labeled 'not for human consumption,' which is not an authorized channel for human use. Practitioners should verify current compounding status before prescribing.
International
The European Medicines Agency and UK MHRA have not authorized ipamorelin as a medicine. Australia's TGA classifies GH secretagogues as Schedule 4 prescription-only substances. Canada treats it as an unapproved investigational agent.
Sports & Competition
Ipamorelin is explicitly prohibited under WADA's S2 category (Peptide Hormones, Growth Factors, Related Substances and Mimetics), which names GH secretagogues and GHS-R agonists — prohibited at all times, both in and out of competition. Detection assays for ipamorelin and its metabolites in urine (via LC-MS/MS) are well-established. Athletes subject to WADA, USADA, UKAD, or equivalent bodies must avoid it.
Regulatory status changes over time. Verify current local rules with a qualified professional.
Myths & Misconceptions
Myth
Ipamorelin is completely side-effect free because it's selective.
Reality
The selectivity profile (no significant cortisol, ACTH, or prolactin elevation) is real and well-documented in preclinical work — that's what distinguishes it from GHRP-6 and hexarelin. But it still raises IGF-1, still causes mild water retention and appetite increase in some users, and still carries the theoretical IGF-1-mediated concerns about cancer promotion. 'Clean relative to other GHRPs' is not 'clean absolutely.'
Myth
Ipamorelin is FDA-approved for anti-aging.
Reality
Ipamorelin is not FDA-approved for any indication. It has been studied for postoperative ileus and cachexia but no approval has resulted. Compounding-pharmacy access has narrowed following the 2023 FDA bulk-list review.
Myth
The CJC-1295 + ipamorelin stack is a substitute for HGH that avoids its risks.
Reality
The stack preserves physiological pulsatility better than flat exogenous rhGH dosing, which does plausibly attenuate some side effects like edema and carpal tunnel symptoms. But the downstream effector — IGF-1 — is the same pathway, and the theoretical long-term concerns that attach to sustained IGF-1 elevation attach to the stack too. It is 'HGH-like effects via a different mechanism,' not a fundamentally different risk category.
Myth
Ipamorelin won't show up on a drug test.
Reality
WADA-accredited labs have LC-MS/MS methods for detecting ipamorelin and its metabolites in urine. It is explicitly prohibited under S2 at all times. Athletes have been sanctioned.
Myth
Ipamorelin works regardless of when you dose it — meals don't matter.
Reality
Ipamorelin acts at the ghrelin receptor, and GH response is substantially blunted by elevated insulin and circulating amino acids. Dosing on a relatively empty stomach (≥30 min before eating, or 2+ hours after a meal) meaningfully affects the size of the GH pulse. This is why bedtime dosing is so common — it aligns with both the fasted state and the natural nocturnal GH pulse.
Published Research
15 studiesThe growth hormone secretagogue receptor 1a agonists, anamorelin and ipamorelin, inhibit cisplatin-induced weight loss in ferrets: Anamorelin also exhibits anti-emetic effects via a central mechanism
The influence of ghrelin agonist ipamorelin acetate on the hypothalamic-pituitary-testicular axis in a cichlid fish, Oreochromis mossambicus
Determination of growth hormone releasing peptides metabolites in human urine after nasal administration of GHRP-1, GHRP-2, GHRP-6, Hexarelin, and Ipamorelin
Prospective, randomized, controlled, proof-of-concept study of the Ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients
Proof-of-concept RCT testing ipamorelin for postoperative ileus in bowel resection patients, providing one of the few controlled human efficacy datasets for the peptide in a clinical setting.
Efficacy of ipamorelin, a novel ghrelin mimetic, in a rodent model of postoperative ileus
Mechanism of ipamorelin-evoked insulin release from the pancreas of normal and diabetic rats
Influence of chronic treatment with the growth hormone secretagogue Ipamorelin, in young female rats: somatotroph response in vitro
The growth hormone secretagogue ipamorelin counteracts glucocorticoid-induced decrease in bone formation of adult rats
Highly potent growth hormone secretagogues: hybrids of NN703 and ipamorelin
The GH secretagogues ipamorelin and GH-releasing peptide-6 increase bone mineral content in adult female rats
Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers
Key human PK/PD study establishing ipamorelin's dose-response profile in healthy volunteers, demonstrating potent GH release with a bell-shaped dose-response curve and confirming its favorable selectivity — no significant effect on ACTH, cortisol, or prolactin.
Ipamorelin, a new growth-hormone-releasing peptide, induces longitudinal bone growth in rats
Pharmacokinetic evaluation of ipamorelin and other peptidyl growth hormone secretagogues with emphasis on nasal absorption
Ipamorelin, the first selective growth hormone secretagogue
Foundational paper defining ipamorelin as the first truly selective GH secretagogue, demonstrating in swine and rats that it releases GH without affecting ACTH, cortisol, prolactin, or aldosterone — even at doses 200-fold above the effective GH-releasing dose.
A new series of highly potent growth hormone-releasing peptides derived from ipamorelin
Popular Stacks Including Ipamorelin
CJC-1295 + Ipamorelin (The GH Secretagogue Stack)
The classic growth hormone secretagogue stack — often called the GH stack or sleep stack. Combines GHRH signaling (CJC-1295) with selective ghrelin receptor activation (ipamorelin) to amplify the body's natural nighttime growth hormone pulse.
Tesamorelin + Ipamorelin (FDA-Backed GHRH Analog + Selective Ghrelin-Mimetic)
A growth hormone secretagogue stack that pairs the only FDA-approved GHRH analog (tesamorelin) with the cleanest ghrelin-receptor trigger (ipamorelin). Delivers the same GHRH + ghrelin dual-pathway synergy as CJC-1295 + ipamorelin, with tesamorelin's Phase III evidence base standing in for the compounded GHRH leg.
Quick Facts
- Class
- Growth Hormone Secretagogue
- Tier
- C
- Evidence
- Moderate
- Safety
- Moderate Data
- Updated
- Apr 2026
- Citations
- 15PubMed
Also known as
Tags
Peptide Families
Related Goals
Evidence Score
Clinical Trials
View Clinical TrialsLinks to ClinicalTrials.gov for reference. Listing does not imply endorsement.