Sermorelin / GHRP
Sermorelin combined with GHRP-2 or GHRP-6 (compounding pharmacy growth hormone blend)
Written by Aaron CuhaReviewed Sep 2026
Also known as: Sermorelin/GHRP-2, Sermorelin/GHRP-6, Sermorelin GHRP blend
In plain English, from Aaron
This is how I would explain it to a friend. The evidence, with the numbers, is further down the page.
This is the old growth hormone blend that compounding pharmacies make. It is usually 5 mg of each in a 10 mg vial. One half is a fragment of your own growth hormone signal, and it used to be an approved drug called Geref. The other half is a peptide that copies your hunger hormone. Both push your pituitary to release growth hormone. They just do it through different doors.
What people take it for
- Better sleep.
- Losing fat and keeping muscle.
- Recovering faster from training.
- Feeling younger as growth hormone drops with age.
What the trials actually showed
This is the one blend on this site where the pairing itself has been tested in people. Be clear on what that test was. In 20 patients, the hunger type peptide alone gave a growth hormone peak of 25.7. Add the other type and it jumped to 54.7. Another study gave 26 people both at once through an IV. Peaks ran 47.5 to 76.0 and worked just as well in the oldest group. So the pairing is real. But every one of those was a single IV dose in a clinic, used as a test for a hormone problem. None measured fat, muscle, sleep or anything you would buy this for. Now the doses in the vial. Reconstituted the normal way, a standard 200 to 300 microgram draw gives you the same amount of both. Compare that to the research. The hunger type peptide has a tested dose of 100 micrograms, given once, through an IV, as a test. So a nightly shot is two to three times that, every night. The other half goes the other way. Its best human study gave 1 mg twice a day for two weeks to 10 older men. That brought their growth hormone and IGF-1 back to young levels. That dose is three to five times what the vial gives you. So this blend gives too little of the half with the better evidence and too much of the half with the thinner evidence. One more finding matters. People were given both for 7 to 30 days. Whether the effect faded depended on the dose and how often they took it. Those are the two things a fixed vial will not let you change.
What people report
Reports, not trial results
The good
- Deeper sleep in the first week or two. The most consistent report on this kind of blend.
- Better recovery and less joint soreness after a few weeks.
- A warm flushed face soon after the shot, which people take as a sign it is working. Flushing did show up in the controlled study.
The bad
- Hunger that hits hard 20 to 30 minutes after the shot. In a trial, one of these peptides raised how much 7 lean men ate by about 36 percent. This is the thing that ends most blend runs.
- Puffy hands, water weight and stiff mornings.
- Tingling or numb fingers.
- The effect fading after two or three months.
- Red lumps at the injection site from a nightly shot.
- If the hunger is what breaks you, you cannot cut just that half. It is one vial. You cut both or you stop.
Where these come from: Flushing and the jump in food intake both come from real trials and are cited on this page. The sleep, recovery, water weight and fade over time reports come from peptide forums and clinic write ups, and none of that is from a trial of a compounded blend.
My bottom line
This is the strongest case any blend on this site can make. It is still a hormone spike in a clinic, not a result you can feel. Hunger is what ends most of these runs, and a single vial is the one format that will not let you deal with it.
An opinion, not a finding. I am a coach, not a doctor.
Overview
The standard compounding pharmacy growth hormone blend, usually sold as 5 mg sermorelin with 5 mg GHRP-2 in one 10 mg vial. This is the only blend on this site where the class combination has genuine human data: adding a GHRH to GHRP-6 roughly doubled the acute growth hormone peak, 54.7 against 25.7 micrograms per litre in 20 patients. That was a single intravenous diagnostic test in a hospital, not a nightly subcutaneous protocol, and the specific vial has never been studied.
Sermorelin plus a growth hormone releasing peptide is the oldest configuration of this idea and the one with the most real science underneath it. Sermorelin is GHRH 1-29, the shortest fully active fragment of growth hormone releasing hormone, and it was an FDA-approved drug marketed as Geref for diagnosing and treating growth hormone deficiency before it was discontinued. GHRP-2 is pralmorelin, approved in Japan as a diagnostic test of pituitary function. GHRP-6 is the first-generation hexapeptide that opened the whole field. These are not invented molecules with no history; they are old drugs that fell out of the approved column for commercial reasons.
The combination also has more behind it than any other page in this batch, and it is worth being precise about what that evidence is and is not. In 20 patients tested for growth hormone deficiency, GHRP-6 at 1 microgram per kilogram alone produced a mean peak of 25.7 micrograms per litre in the growth hormone sufficient group, and GHRP-6 with GHRH at the same weight-based dose produced 54.7. In 26 subjects spanning ages 19 to 96, a combined intravenous bolus of 90 micrograms GHRH plus 90 micrograms GHRP-6 produced growth hormone peaks of 47.5 to 76.0 micrograms per litre with no significant decline across age groups and no non-responders. Both of those are diagnostic tests: one dose, intravenously, in a clinic, with blood drawn over 90 to 120 minutes. Neither measured body fat, muscle, sleep or anything else a person would buy a blend for.
The chronic picture is where it gets interesting and where the blend format starts to hurt. Bowers and Granda-Ayala gave younger and older men and women GHRP-2, GHRH, or the two together for 7 to 30 days. Chronic administration of either component could convert an additive combined response into a synergistic one, and the type of synergy differed depending on which one was given chronically. Critically, whether the growth hormone response desensitised at all depended on the dose and the frequency of administration. That is the finding a fixed-ratio vial ignores: the two variables that decide whether the pairing keeps working or fades are exactly the two variables the blend takes away from you.
Now the arithmetic. The common compounded blend is a 10 mg vial split 5 mg sermorelin and 5 mg GHRP-2, so each peptide is half the powder by mass. By molecule count it is not close. Sermorelin weighs 3,357.9 Da and GHRP-2 weighs 817.0 Da, so an equal-mass vial delivers about 4.1 GHRP-2 molecules for every sermorelin molecule; with GHRP-6 at 873.0 Da the ratio is about 3.8 to 1. Reconstituted in 2 mL, a 5 plus 5 vial holds 2.5 mg per mL of each, so the standard 200 to 300 microgram sermorelin dose is an 8 to 12 unit draw that also delivers 200 to 300 micrograms of GHRP. Set that against the human record: GHRP-2's validated diagnostic dose is 100 micrograms intravenously, and the combined-test GHRP-6 dose was 90 micrograms. A nightly blend draw therefore delivers two to three times the GHRP dose that appears anywhere in the published human literature, and delivers it every night rather than once as a test.
The sermorelin half goes the other way. The human study most often cited for it gave GHRH 1-29 at 1 mg twice daily for 14 days to 10 healthy older men and restored 24-hour growth hormone and IGF-1 to levels not significantly different from young men. That is 1,000 micrograms per dose, three to five times what a blend draw delivers. So the standard blend under-doses the component with the better human evidence and over-doses the component whose human record is a single acute diagnostic test.
Mechanism of action
Sermorelin activates the pituitary GHRH receptor, raising growth hormone pulse amplitude while preserving hypothalamic feedback. GHRP-2 and GHRP-6 activate the growth hormone secretagogue receptor GHS-R1a, a separate receptor cloned in 1996, releasing growth hormone and suppressing somatostatin tone. Because the two receptors are distinct and somatostatin withdrawal amplifies the GHRH signal, the combined response is larger than either alone, and in human testing roughly double. GHRP-6 in particular also raises appetite, cortisol and prolactin, which is why the later, more selective secretagogues were developed.
Human evidence
This is the one blend in this batch where the class combination has been given to humans and measured. What was measured was an acute growth hormone peak from a single intravenous dose in a diagnostic setting, using GHRH and GHRP-6 or GHRP-2 rather than the compounded vial anyone buys.
- GHRP-6 alone versus GHRP-6 plus GHRH, 20 patients: mean peak growth hormone 25.7 against 54.7 micrograms per litre in the growth hormone sufficient group. Flushing was the only side effect seen.
- GHRH 90 micrograms plus GHRP-6 90 micrograms, 26 subjects aged 19 to 96: peaks of 47.5 to 76.0 micrograms per litre, no significant age effect, no non-responders.
- GHRP-2 with GHRH for 7 to 30 days: the additive response could become synergistic, and desensitisation depended on dose and frequency.
- Sermorelin as GHRH 1-29, 1 mg twice daily for 14 days in 10 old men: 24-hour growth hormone and IGF-1 restored to young levels.
- GHRP-2 alone, validated in 77 healthy subjects and 58 growth hormone deficient patients as a 100 microgram intravenous diagnostic test with a 15 microgram per litre cut-off.
- GHRP-2 infusion in 7 lean men increased food intake by about 36 percent.
What this does not tell you: Every combination study above is an acute intravenous test designed to diagnose growth hormone deficiency, run once, with blood drawn for 90 to 120 minutes. None of them measured fat, muscle, strength, sleep, recovery or any outcome a person takes a blend for. None used the subcutaneous route, the nightly schedule, the doses or the ratio in a compounded vial. The chronic study that did run 7 to 30 days measured hormone responses, not outcomes. No published work describes the stability of sermorelin and a GHRP in one vial, and no dose-finding study exists for the pair at any ratio.
Reading the research record
This page should be read as the strongest version of the blend argument, and it is still not strong. The class pairing works pharmacologically, was demonstrated in humans decades ago, and roughly doubles an acute growth hormone peak. That is a real finding and it is fair to report it. What it is not is evidence that a nightly compounded vial changes body composition, and the leap from the first to the second is the leap this whole category of product is built on.
The economics explain the silence. Sermorelin's approval was discontinued, GHRP-6's patents are long gone, and GHRP-2 sits in a narrow Japanese diagnostic approval. None of the three can support the cost of a modern outcome trial, so the literature froze in the 1990s and 2000s at the point where the hormone response had been characterised and the clinical question had not been asked. A thin record here is an economic fact rather than a verdict, which is precisely why the honest framing is unknown rather than disproven.
The fixed-ratio problem is sharpest on the secretagogue side. GHRP-6 raises appetite hard through the ghrelin receptor, and GHRP-2, marketed as the cleaner one, still raised food intake by about 36 percent in lean men. Appetite is the most common reason people abandon these blends, and on a single vial the only way to reduce the GHRP is to reduce the sermorelin with it. The same applies to prolactin and cortisol elevations, which differ between the secretagogues and which are the reason later work moved toward more selective molecules. If you want the GHRH without that particular secretagogue's baggage, a blend is the one format that will not let you have it.
The evidence, charted
Fig. 1 · evidence composition
5of 6 citations (83%) are in people
Counted from the citation list on this page. The Human count is the same number shown in the badge at the top. Both understate any literature larger than the sources we cite.
Fig. 2 · evidence over time
Evidence spans 6 distinct years, 1992 to 2005, counted from the citation list on this page. The newest citation on file is from 2005, more than five years ago; the published record may have gone quiet.
Fig. 3 · legal status at a glance
US
Approved
UK
Not approved
AU
Not approved
CA
Not approved
Approved in 1 of 4, prescription route in 0, not approved in 3. A jurisdiction's classification is a regulatory fact, not a verdict on the science; see Legal status below for the full text and any notes.
Fig. 4 · dose response
No human dose response curve exists
We draw this figure where the data supports it. For this compound in humans it does not, so the panel stays empty rather than borrowing an animal curve and implying it transfers.
Key studies & citations
- Human1992
Growth hormone (GH)-releasing hormone-(1-29) twice daily reverses the decreased GH and insulin-like growth factor-I levels in old men
In 10 healthy old men, 14 days of GHRH 1-29 at 1 mg twice daily restored 24-hour growth hormone and IGF-1 to levels not significantly different from young men. The best human result for the sermorelin half, and note the dose: 1,000 micrograms twice a day, several times what a blend draw delivers.
Journal of Clinical Endocrinology and Metabolism - Human2002
Diagnosis of growth hormone deficiency in adults by testing with GHRP-6 alone or in combination with GHRH: comparison with the insulin tolerance test
Twenty patients received GHRP-6 at 1 microgram per kilogram alone and, on a separate day, GHRP-6 with GHRH at 1 microgram per kilogram. In the growth hormone sufficient group the mean peak was 25.7 micrograms per litre alone and 54.7 combined; in the deficient group 1.3 versus 4.0. The combination is genuinely better than the secretagogue alone, measured as a single intravenous diagnostic test. Flushing was the only side effect observed.
European Journal of Endocrinology - Human1998
Preserved growth hormone (GH) secretion in aged and very old subjects after testing with the combined stimulus GH-releasing hormone plus GH-releasing hexapeptide-6
26 normal subjects in three age bands from 19 to 96 given a combined intravenous bolus of 90 micrograms GHRH plus 90 micrograms GHRP-6. Mean growth hormone peaks were 47.5, 52.9 and 76.0 micrograms per litre with no significant differences between age groups, and there were no non-responders. Shows the combined stimulus still works in old people, as a one-off test.
Journal of Clinical Endocrinology and Metabolism - Human1996
GHRP-2, GHRH and SRIF interrelationships during chronic administration of GHRP-2 to humans
Younger and older men and women received GHRP-2, GHRH, or GHRP-2 plus GHRH for 7 to 30 days. Chronic dosing of either could convert an additive combined response into a synergistic one, and the type of synergy differed by which was given chronically. Whether the response desensitised depended on dose and frequency, which are the two things a fixed-ratio vial prevents you from adjusting.
Journal of Pediatric Endocrinology and Metabolism - Human2005
Growth hormone releasing peptide-2 (GHRP-2), like ghrelin, increases food intake in healthy men
A GHRP-2 infusion increased ad libitum food intake by about 36 percent in seven lean men alongside a strong growth hormone rise. This is the side effect that most often ends a blend course, and the one you cannot remove without also removing the sermorelin.
Journal of Clinical Endocrinology and Metabolism - Review1999
Sermorelin: a review of its use in the diagnosis and treatment of children with idiopathic growth hormone deficiency
Sermorelin as GHRH 1-29 is the shortest fully active GHRH fragment. An intravenous 1 microgram per kilogram dose is a rapid and relatively specific diagnostic test, and daily subcutaneous dosing at 30 micrograms per kilogram treated some prepubertal children with growth hormone deficiency. The regulatory history behind the sermorelin half, in children with a diagnosed deficiency.
BioDrugs
What users report
Self-reported experiences, not evidence. Nothing below was measured under controlled conditions, and reports like these cannot separate a real effect from placebo, from the training or diet change that accompanied it, or from what the product actually contained. They are here because knowing what people describe, including what goes wrong, is worth reading alongside the studies.
- Deeper sleep within the first one to two weeks, the most consistent report on any GHRH plus secretagogue combination.
- A strong hunger surge starting 20 to 30 minutes after the injection, which is much more pronounced on GHRP-6 blends than GHRP-2 blends and matches the ghrelin receptor pharmacology.
- Better recovery from training and less joint soreness after several weeks.
- Flushing and a warm face shortly after injection, which is the one side effect that also appeared in the controlled diagnostic study.
- Water retention, puffy hands and morning stiffness.
- Tingling or numbness in the fingers.
- The effect fading after two to three months, which users call desensitisation and which the chronic human study says depends on dose and frequency rather than being inevitable.
- Injection site redness and small lumps from nightly subcutaneous dosing.
Sources: Flushing is documented in the controlled GHRP-6 plus GHRH diagnostic study, and the appetite effect is documented in the GHRP-2 food intake trial, so those two are trial-derived. The sleep, recovery, water retention and fade-over-time reports come from peptide user forums and from clinic write-ups and are not from any trial of a compounded blend. The 2026 Frontiers in Endocrinology review of self-administered growth hormone axis peptides lists the same adverse effect domains, including prolactin and cortisol elevations, fluid retention, myalgia and arthralgia and dysglycaemia.
Frequently asked questions
Is this the one blend with actual combination evidence?
Close to it, with an important qualifier. The class pairing has been tested in people: adding GHRH to GHRP-6 roughly doubled the acute growth hormone peak, 54.7 against 25.7 micrograms per litre in 20 patients. But that was a single intravenous dose in a hospital as a diagnostic test, not a compounded vial injected nightly, and it measured a hormone peak rather than any outcome.
What is the split in the vial and what does one shot deliver?
The common configuration is a 10 mg vial split 5 mg sermorelin and 5 mg GHRP-2, so half the powder is each by mass. Reconstituted in 2 mL that is 2.5 mg per mL of each, so a standard 200 to 300 microgram sermorelin dose is an 8 to 12 unit draw that carries the same 200 to 300 micrograms of GHRP. By molecule count, equal mass gives you about four GHRP-2 molecules for every sermorelin molecule, because sermorelin is roughly four times heavier.
Are those doses in line with the research?
Neither of them is. The GHRP-2 diagnostic dose validated in 77 healthy subjects and 58 patients is 100 micrograms intravenously, given once as a test, so a nightly blend draw is two to three times that, repeatedly. The sermorelin study most often quoted used 1 mg twice daily for 14 days, which is three to five times what the blend delivers. The vial under-doses the half with the better evidence and over-doses the half with the thinner evidence.
GHRP-2 or GHRP-6 in the blend?
GHRP-6 raises appetite hardest and also raises cortisol and prolactin more, which is why the later peptides were developed. GHRP-2 is more selective but its appetite effect is reduced rather than absent: an infusion raised food intake by about 36 percent in seven lean men. If appetite is a problem for you, the blend format is the wrong one, because you cannot lower the secretagogue on its own.
Will it stop working after a few months?
That is the common forum belief and the human data is more specific than that. In a study running 7 to 30 days, whether the growth hormone response desensitised depended on the dose and the frequency, and chronic dosing could actually turn an additive response into a synergistic one. Dose and frequency are the two levers that decide it, and a fixed-ratio vial removes half of your ability to use them.
Is sermorelin a real drug or a peptide from the internet?
Both, at different times. It was FDA-approved as Geref for diagnosing and treating growth hormone deficiency, and that approval was discontinued for commercial reasons rather than safety ones. Today it reaches people through compounding pharmacies, which means it is not FDA-reviewed for safety, purity or efficacy in the form you receive it.