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Ipamorelin

Growth HormoneResearch-Grade

Last reviewed: May 23, 2026

Also Known As: NNC 26-0161, GHRP, Selective Growth Hormone Secretagogue

Peptide Class: Synthetic Pentapeptide — Selective GHSR-1a (Ghrelin Receptor) Agonist

Regulatory Status: Not FDA-approved; research-use only. WADA-prohibited (Section S2). Phase 2 development discontinued.

What is Ipamorelin?

Ipamorelin is a synthetic pentapeptide (Aib-His-D-2-Nal-D-Phe-Lys-NH2) developed by Novo Nordisk in the late 1990s as a selective agonist of the ghrelin/growth hormone secretagogue receptor (GHSR-1a). Unlike other GHRPs (GHRP-2, GHRP-6), ipamorelin stimulates growth hormone release without elevating cortisol, prolactin, ACTH, FSH, LH, or TSH — making it the most selective GHRP available. It was investigated in Phase 2 trials for postoperative ileus but discontinued for lack of efficacy in that specific indication. Often paired with CJC-1295 as the GH Stack — the two activate different receptor pathways and produce synergistic GH release. New to peptide research? Start with the basics →

Reported benefits:

  • Stimulates pulsatile growth hormone release via the ghrelin receptor pathway
  • Highly selective for GH — does not affect cortisol, prolactin, or other pituitary hormones
  • Increases IGF-1 levels through GH-mediated pathway
  • Supports lean muscle growth and fat reduction (downstream of GH)
  • Improved sleep quality reported, especially with bedtime dosing
  • Bone formation support (counters glucocorticoid-induced bone loss in animal models)

Common research dose: Most research protocols use 200–300 mcg subcutaneously, 1–3 times daily. Bedtime dosing is most common to align with natural GH circadian peaks. Cycle length is typically 8–12 weeks. Empty-stomach dosing is required for full GH response.

Where to buy: PP maintains a vetted list of peptide vendors with verified discount codes. See Verified Discount Codes → for current options.

How does Ipamorelin work?

Ipamorelin selectively binds the ghrelin/growth hormone secretagogue receptor (GHSR-1a) on pituitary somatotrophs, triggering pulsatile GH release through the cAMP/PKA pathway. Unlike GHRP-2 and GHRP-6, ipamorelin does NOT stimulate cortisol, ACTH, prolactin, or TSH — even at doses 200x above the GH-releasing dose. This selectivity is its primary clinical advantage and the reason it pairs cleanly with CJC-1295 (which works through a different receptor) for synergistic GH release.

  1. GHSR-1a Receptor Activation [1]. Ipamorelin selectively binds the growth hormone secretagogue receptor (GHSR-1a, the ghrelin receptor) on pituitary somatotroph cells and hypothalamic neurons. This is the same receptor activated by endogenous ghrelin — ipamorelin acts as a synthetic ghrelin mimic with much greater receptor selectivity.
  2. cAMP/PKA Signaling [2]. Receptor activation triggers a Gαq-coupled signaling cascade that increases intracellular calcium and cAMP production, activating protein kinase A. This drives the synthesis and release of stored growth hormone from somatotrophs.
  3. Pulsatile GH Release [1]. Ipamorelin amplifies the natural pulsatile pattern of GH secretion rather than creating a continuous flood. This preserves the hypothalamic-pituitary feedback loops that regulate GH homeostasis, which is mechanistically safer than direct GH administration.
  4. Selectivity for GH [1][3]. Unlike GHRP-2 and GHRP-6, ipamorelin does NOT stimulate cortisol, ACTH, prolactin, FSH, LH, or TSH release. Even at doses 200x higher than the GH-releasing dose, no meaningful effect on these other hormones is observed. This selectivity is its primary clinical advantage.
  5. Somatostatin Antagonism [4]. Ipamorelin reduces the inhibitory effect of somatostatin (GH-inhibiting hormone), allowing the pituitary's GH-releasing activity to remain elevated longer than it would otherwise.

What is Ipamorelin used for?

Ipamorelin's research evidence base spans GH stimulation (animal and human PK studies), body composition (downstream of GH/IGF-1), bone formation (counters glucocorticoid-induced bone loss), postoperative ileus (Phase 2, discontinued for lack of efficacy in that specific indication), and cognitive/sleep applications. Most evidence is from animal models and the discontinued Phase 2 program; long-term controlled human trials are limited.

  1. Growth Hormone Stimulation [1][3]. Multiple animal and human studies confirm ipamorelin produces GH release with potency comparable to GHRP-6 but greater selectivity. Effects observed in primary rat pituitary cells (EC50 ~1.3 nmol/L) and pentobarbital-anaesthetized rat models.
  2. Body Composition Research. IGF-1 elevation downstream of ipamorelin-induced GH release supports lean muscle synthesis and lipolysis. Most ipamorelin body composition data comes from clinical practice rather than controlled trials.
  3. Bone Formation [4]. In adult female rats, ipamorelin counteracted glucocorticoid-induced decreases in bone formation. The GH secretagogues ipamorelin and GHRP-6 increased bone mineral content in adult female rats.
  4. Postoperative Ileus (Discontinued). Helsinn Therapeutics took ipamorelin through Phase 2 trials for postoperative ileus but discontinued for lack of efficacy in that specific indication. The compound itself was safe — it just didn't address that specific problem effectively.
  5. Cognitive and Sleep Research. Anecdotal and clinical observations suggest improved sleep quality with bedtime dosing, likely due to alignment with natural GH circadian peaks. Limited controlled human data.

How long does Ipamorelin take to work?

Ipamorelin effects build over weeks of consistent dosing. Most users notice improved sleep within 1–2 weeks. Body composition changes (increased lean mass, reduced fat) typically emerge over 8–12 weeks. IGF-1 elevation can be measured within days of starting therapy. Half-life is short (~2 hours), so effects depend on consistent dose timing rather than sustained blood levels.

Most users notice improved sleep quality within 1–2 weeks of consistent bedtime dosing — often the first noticeable subjective effect. Body composition changes (increased lean mass, reduced fat) typically emerge over 8–12 weeks. IGF-1 elevation can be measured in blood work within days of starting therapy. Half-life is short (~2 hours), so effects depend on consistent timing rather than sustained blood levels — bedtime dosing maintains alignment with the natural overnight GH peak.

How is Ipamorelin dosed?

Ipamorelin is administered as a subcutaneous injection. The 2-hour half-life means effects depend on dose timing rather than continuous coverage. Standard dosing is 200–300 mcg subcutaneously per injection, with bedtime as the most common protocol (aligns with natural overnight GH peak). Frequently stacked with CJC-1295 (with or without DAC) for synergistic dual-pathway GH release.

  1. Standard dose. 200–300 mcg subcutaneously per injection.
  2. Bedtime dosing. 200–300 mcg before sleep — most common protocol, aligns with natural GH peak during deep sleep.
  3. Multiple daily dosing. 200 mcg 2–3x per day (morning, mid-day, bedtime) for users targeting sustained effect.
  4. Pre-workout dosing. Some users add a 200 mcg dose 30–60 minutes before training to amplify exercise-induced GH release.
  5. Cycle length. 8–12 weeks on, with at least 4 weeks off; some protocols run continuously for 6+ months under clinical supervision.

Ipamorelin is frequently stacked with CJC-1295 (with or without DAC). The combination produces greater GH release than either alone because they activate different receptor pathways simultaneously — ipamorelin via GHSR-1a, CJC-1295 via GHRH receptor. See the GH Stack page for the combined protocol.

Need to calculate your dose? Convert mg to syringe units and plan reconstitution with the dosage calculator →.

How is Ipamorelin administered?

Ipamorelin is given as a subcutaneous injection — under the skin, not into muscle — 1–3 times daily using a small insulin syringe. Bedtime dosing aligns with the natural overnight GH peak. Empty-stomach timing maximizes the GH response — insulin from food blunts GH release. For the practical mechanics of insulin syringes, units vs mcg conversion, and subcutaneous technique, see the syringes and injection technique guide.

  1. Route. Subcutaneous injection. Common sites: abdomen, thigh, upper arm.
  2. Time of day. Bedtime is most common. Inject 30–60 minutes before sleep on an empty stomach.
  3. With or without food. Best on empty stomach (2+ hours after eating, no food for 30 min after) to maximize GH release. Food spikes insulin, which blunts GH secretion.
  4. Site rotation. Use a different site each injection to reduce localized irritation. Stay at least 1 inch from previous injection sites.
  5. Hunger spike. Brief increase in appetite is expected for 30–60 minutes after injection (ghrelin receptor activation). Bedtime dosing lets you sleep through this.
  6. Missed dose. Skip and resume next scheduled dose. Do not double-dose.
  7. Cycle structure. 8–12 weeks on, 4+ weeks off.

Timing context. Ipamorelin's 2-hour half-life means each dose produces a discrete GH pulse rather than sustained elevation. The body's largest natural GH release happens in the first 90 minutes of deep sleep — bedtime dosing (30–60 min before sleep) stacks the ipamorelin pulse onto this natural peak. Empty-stomach timing matters more than time of day in absolute terms: insulin secreted in response to food blunts the GH response substantially.

AspectRecommendation
Frequency1–3× daily during the cycle (most users dose once at bedtime)
Best time of dayBedtime preferred — aligns with natural overnight GH peak
FoodEmpty stomach required — 2+ hours after eating, 30+ min before next meal
Injection site rotationRotate between abdomen, thigh, upper arm
Half-life~2 hours
Steady-statePer-pulse effect rather than traditional steady-state — each dose triggers a discrete GH pulse

Reconstitution math. Choose your bacteriostatic water volume based on dose precision. Lower water volume = higher concentration = smaller syringe draw. Ipamorelin research vials are typically 5 mg. Because doses are small (200–300 mcg), 2 mL or 3 mL reconstitution is common — it gives more precise unit draws at low dose. All units below are measured on a U-100 insulin syringe (100 units = 1 mL). The table assumes a 5 mg vial.

BAC waterConcentration100 mcg dose200 mcg dose300 mcg dose500 mcg dose
1 mL5 mg/mL2 units4 units6 units10 units
2 mL2.5 mg/mL4 units8 units12 units20 units
3 mL1.67 mg/mL6 units12 units18 units30 units

Units vs mcg. At a 5 mg vial, each unit drawn delivers 50 mcg of Ipamorelin at 1 mL reconstitution, 25 mcg at 2 mL, and 16.7 mcg at 3 mL — the reconstitution volume determines the mcg-per-unit conversion. For a primer on reading insulin syringes and choosing the right barrel size, see our guide on syringes and injection technique.

What does Ipamorelin stack well with?

Ipamorelin's canonical pairing is CJC-1295 — the dual-pathway GH Stack (ghrelin receptor + GHRH receptor) produces synergistic GH release greater than either alone. The recovery peptides (BPC-157, TB-500) pair cleanly for systemic recovery during anabolic protocols. IGF-1 LR3 stacks for direct receptor activation alongside endogenous GH stimulation — space injections 2–3 hours apart to avoid receptor competition. Avoid other GHRPs (GHRP-2, GHRP-6, MK-677) — redundant ghrelin-pathway mechanism.

  1. CJC-1295 (GH Stack). The most popular pairing. CJC-1295 activates the GHRH receptor while ipamorelin activates the ghrelin receptor — dual-pathway activation produces synergistic GH release. See the GH Stack page for the combined protocol.
  2. BPC-157 / TB-500. Wolverine Stack paired for recovery support. The healing peptides accelerate tissue repair while ipamorelin supports the GH-driven anabolic environment.
  3. IGF-1 LR3. IGF-1 LR3 combined for direct IGF-1 receptor activation alongside endogenous GH stimulation. Inject IGF-1 LR3 at least 2–3 hours apart from ipamorelin to avoid receptor competition.
  4. Resistance training. Natural pairing — exercise-induced GH release is amplified when paired with ipamorelin's pulse.
  5. Avoid: other GHRPs. GHRP-2, GHRP-6, and MK-677 all activate the same ghrelin receptor — combination is redundant with no additive benefit.

What are the side effects of Ipamorelin?

Ipamorelin has one of the cleanest safety profiles of any GHRP because of its selectivity. It does NOT raise cortisol (a problem with GHRP-2 and GHRP-6) and does not affect prolactin or other pituitary hormones. The most-reported user effects are mild injection-site reactions and a brief hunger spike (ghrelin receptor activation, 30–60 minutes post-injection). Long-term safety data beyond 12 weeks is limited.

Common (most users)

  1. Injection site reactions. Mild redness or irritation, typically resolves within hours.
  2. Increased hunger. Transient (30–60 minutes post-injection) due to ghrelin receptor activation; diminishes with continued use.
  3. Mild fatigue or sleepiness. Often appears in the hour following injection — one reason bedtime dosing is preferred.

Less common (moderate)

  1. Mild headache. Inconsistent across users.
  2. Slight numbness or tingling. Uncommon; related to GH-induced fluid retention.
  3. Mild fluid retention. Inconsistent; typically appears with long-term use.

Serious (rare)

  1. Long-term safety data beyond 12 weeks is limited. Most controlled studies were short-duration.
  2. Theoretical tumor growth risk. GH/IGF-1 elevation could accelerate pre-existing tumors. Contraindicated with active malignancy.
  3. Severe allergic reactions. Rare and not commonly reported.

Ipamorelin has one of the cleanest safety profiles of any GHRP because of its selectivity. It does NOT raise cortisol (a problem with GHRP-2 and GHRP-6) and does not affect prolactin or other pituitary hormones. Long-term use should be monitored for IGF-1 elevation and glucose tolerance — both rise modestly with sustained GH stimulation.

Does Ipamorelin interact with other drugs?

Ipamorelin's interactions are mostly about avoiding redundancy with other GHRPs (GHRP-2, GHRP-6, MK-677 — same ghrelin receptor) or with direct GH (which bypasses the regulatory feedback that makes ipamorelin safer). Insulin and corticosteroids blunt GH release; time dosing away from meals and steroid administration. No significant drug-drug pharmacokinetic interactions reported.

  1. Insulin and corticosteroids. Both blunt GH release; consider timing dosing away from meals and steroid administration.
  2. Other GH secretagogues (GHRP-2, GHRP-6, MK-677). Combination is redundant via the same receptor; no additive benefit.
  3. Direct human growth hormone (HGH). Combining is generally unnecessary; ipamorelin stimulates endogenous GH and adding exogenous HGH bypasses the regulatory feedback that makes ipamorelin safer.
  4. No significant drug-drug interactions reported in published research.

How should Ipamorelin be stored?

  1. Lyophilized (powder) form: Store at -20°C for long-term storage; refrigerate at 2–8°C for short-term.
  2. Reconstituted solution: Store at 2–8°C; use within 28–30 days.
  3. Reconstitute with bacteriostatic water for injection (BAC water). Swirl gently — do not shake.
  4. Never freeze reconstituted solution.
  5. Protect from light. Store in original carton.
  6. Discard if cloudy, discolored, or contains particles.

What are the limitations of Ipamorelin research?

Ipamorelin is not FDA-approved for any human use. It was investigated in Phase 2 trials for postoperative ileus by Helsinn Therapeutics but development was discontinued in 2014 due to lack of efficacy in that specific indication — the compound itself was found safe. Most evidence for anti-aging and body composition uses comes from animal models and clinical practice observations rather than controlled human trials. WADA prohibits ipamorelin in sport under Section S2.

Ipamorelin is not FDA-approved for any human use. It was investigated in Phase 2 clinical trials for postoperative ileus by Helsinn Therapeutics but development was discontinued in 2014 due to lack of efficacy in that specific indication. The compound itself was found safe — the trial outcome reflected the unsuitability of the indication, not safety problems.

Most evidence for ipamorelin's anti-aging and body composition uses comes from animal models, small-scale clinical practice observations, and individual case reports rather than controlled human trials. Long-term safety data beyond 12 weeks is limited.

The World Anti-Doping Agency prohibits ipamorelin in sport under Section S2 (peptide hormones). Research-grade material is sold for laboratory use only and is not approved for human consumption.

Where to source Ipamorelin

Ipamorelin is not FDA-approved for any human use and is sold only as a research-grade peptide. The vendors highlighted below have been vetted for transparent third-party testing, traceable batch documentation, and verified discount codes — including pre-mixed CJC-1295/Ipamorelin combo options for the canonical GH Stack pairing.

Peptide Partners10% off
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Editor's Pick — 4-test purity program

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Apollo Peptide Sciences10% off

CJC-1295 / Ipamorelin combo

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Behemoth Labz10% off

Nasal + vial formats

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See all 17 verified vendors →

Ipamorelin FAQ

How is ipamorelin different from GHRP-2 or GHRP-6?

All three are growth hormone-releasing peptides that activate the ghrelin receptor. The critical difference is selectivity. GHRP-2 and GHRP-6 also raise cortisol, prolactin, and ACTH alongside GH. Ipamorelin raises only GH — no significant effect on other pituitary hormones even at very high doses. This makes ipamorelin the cleanest GHRP for long-term use.

Should I stack ipamorelin with CJC-1295?

It's the most popular and synergistic stack in the GH peptide space. Ipamorelin activates the ghrelin receptor; CJC-1295 activates the GHRH receptor. Combined, they produce greater GH release than either alone. Most research protocols use ipamorelin + CJC-1295 (often without DAC) injected together at bedtime — see the GH Stack page for the combined protocol.

Why bedtime dosing?

Your body releases the majority of its daily GH during the first 90 minutes of deep sleep. Injecting ipamorelin 30–60 minutes before sleep capitalizes on and amplifies this natural GH peak. Dosing at other times still works but produces smaller GH pulses.

Will ipamorelin make me hungry?

Yes, briefly. Ipamorelin activates the ghrelin receptor (ghrelin is the body's primary hunger hormone). Many users report increased appetite for 30–60 minutes after injection. This is part of why bedtime dosing is preferred — you can sleep through the hunger spike. The effect tends to diminish over weeks of consistent use.

Does ipamorelin raise cortisol?

No — this is one of its main advantages over other GHRPs. Even at doses 200x higher than the GH-releasing dose, ipamorelin does not raise cortisol or ACTH. GHRP-2 and GHRP-6 do raise these hormones, which is why ipamorelin is preferred for long-term use.

How long until I see results?

Sleep quality improvements often appear within 1–2 weeks. Body composition changes (increased lean mass, reduced fat) typically emerge over 8–12 weeks. IGF-1 elevation can be detected in blood work within days of starting consistent therapy.

Can I take ipamorelin during the day?

Yes, though bedtime alignment with natural GH peaks is most efficient. Some users add a pre-workout dose (30–60 min before training) to amplify exercise-induced GH release. Multiple daily dosing (morning + mid-day + bedtime) is sometimes used for sustained effect, but bedtime alone produces most of the benefit.

Where can I buy ipamorelin?

Ipamorelin is sold by specialty research peptide vendors. PP maintains a list of vetted vendors with verified discount codes — see Verified Discount Codes →.

References

  1. Raun K, Hansen BS, Johansen NL, et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998;139(5):552-61. https://pubmed.ncbi.nlm.nih.gov/9849822/
  2. Wikipedia. Ipamorelin. https://en.wikipedia.org/wiki/Ipamorelin
  3. Johansen PB, Segev Y, Raun K, et al. Ipamorelin, a new growth-hormone-releasing peptide, induces longitudinal bone growth in rats. Growth Horm IGF Res. 1999;9(2):106-13. https://pubmed.ncbi.nlm.nih.gov/10373343/
  4. Andersen NB, Malmlöf K, Johansen PB, et al. The growth hormone secretagogue ipamorelin counteracts glucocorticoid-induced decrease in bone formation of adult rats. Growth Horm IGF Res. 2001;11(5):266-72. https://pubmed.ncbi.nlm.nih.gov/11735237/
  5. Svensson J, Lall S, Dickson SL, et al. The GH secretagogues ipamorelin and GH-releasing peptide-6 increase bone mineral content in adult female rats. J Endocrinol. 2000;165(3):569-77. https://pubmed.ncbi.nlm.nih.gov/10860573/

Published Studies

Plain-English summaries of the peer-reviewed studies behind the claims above. Click any title to read the source paper.

European Journal of Endocrinology / PubMed · 1998Abstract open
Ipamorelin, the First Selective Growth Hormone Secretagogue →

Raun K, Hansen BS, Johansen NL, et al.

The landmark study establishing Ipamorelin as the first growth hormone secretagogue with high selectivity for GH release — meaning it stimulates GH without significantly raising cortisol, prolactin, or ACTH. The study demonstrated that Ipamorelin produced robust GH release in rats comparable to GHRP-6 and hexarelin, but with approximately 90% less cortisol response and no meaningful ACTH elevation. This selectivity profile is what distinguishes Ipamorelin from older GHRPs and makes it the preferred GHRP for stacking with GHRH analogs like CJC-1295.

Growth Hormone & IGF Research / PubMed · 1999Abstract open
Ipamorelin — Effects on Bone Mineral Density and Body Composition in Aged Rats →

Hansen BS, et al.

A 12-week study examining Ipamorelin's effects on body composition and bone health in aged rats — directly relevant to its research application in age-related metabolic decline. Findings included significant increases in bone mineral content, reduced adiposity, and increased lean mass, all attributed to sustained GH/IGF-1 axis activation.

Pharmaceutical Research / PubMed · 1999Abstract open
Pharmacokinetic-Pharmacodynamic Modeling of Ipamorelin in Human Volunteers →

Gobburu JVS, et al.

One of the few human pharmacokinetic studies of Ipamorelin, characterizing how it behaves in the human body. The study modeled the relationship between Ipamorelin plasma concentrations and GH release kinetics in healthy volunteers — confirming that the dose-response relationship seen in animal models translates to humans.

PMC / Sexual Medicine Reviews · 2018Open Access
Beyond the Androgen Receptor — The Role of Growth Hormone Secretagogues in Hypogonadal Males →

Sigalos JT, Pastuszak AW

A clinical review examining Ipamorelin alongside other GH secretagogues for applications in metabolic syndrome and hypogonadism. The paper summarizes Ipamorelin's selectivity advantage over GHRP-2 and GHRP-6 and reviews the synergistic GH response when Ipamorelin is combined with GHRH analogs — documenting 2–4x greater GH AUC compared to either compound in isolation.

Growth HormoneGHRPGHSR AgonistResearch-Grade

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CJC-1295 vs Sermorelin vs Ipamorelin →

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