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Sermorelin + GHRP-2

Also known as Sermorelin/GHRP-2 blend, Serm/GHRP-2, GHRH + GHRP blend

A withdrawn GHRH medicine pre-mixed with a Japanese diagnostic peptide; sound class rationale, no study of the mixture.

preclinical Blends & stacks research chemical

At a glance

Category
Blends & stacks
Status
research chemical
Route
subcutaneous
Half-life
No combined figure exists. Sermorelin has a half-life of roughly 11-12 minutes intravenously in humans and several tens of minutes subcutaneously; GHRP-2 roughly 30 minutes subcutaneously. Both are short, so the two clear on broadly comparable timescales — the one respect in which this blend is better matched than a DAC-conjugated CJC-1295 paired with a short secretagogue.
Onset
GH peaks 15-30 minutes after an injection; any change in body composition would take months and has never been demonstrated for the combination
Molecular weight
Not applicable to a mixture. Individually 3357.9 g/mol for sermorelin and 818.0 g/mol for GHRP-2.
Sequence
Not applicable: a co-lyophilised mixture of GHRH(1-29)-NH2 (YADAIFTNSYRKVLGQLSARKLLQDIMSR-NH2) and a hexapeptide of non-natural amino acids (D-Ala-D-2-Nal-Ala-Trp-D-Phe-Lys-NH2).

The blend is not approved anywhere, and its regulatory shape is unusual. Sermorelin was an approved drug: the FDA cleared it as Geref for growth hormone deficiency in children and as Geref Diagnostic for pituitary function testing. EMD Serono notified the FDA in December 2008 that it was discontinuing both products and asked for the applications to be withdrawn; in a 2013 Federal Register determination the FDA confirmed the withdrawal was not for reasons of safety or effectiveness, which is a commercial fact, not an endorsement. GHRP-2 (pralmorelin) has never been approved as a treatment anywhere, but it is registered in Japan as GHRP Kaken 100, a single-dose intravenous diagnostic agent for assessing pituitary GH reserve. So one component is a medicine that no longer exists as a product and the other is a diagnostic reagent being used as a chronic therapy. Neither of those is the same thing as an approved treatment, and the mixture is neither.

Doping status: Prohibited at all times (WADA S2): sermorelin as a GH-releasing factor, GHRP-2 as a growth hormone secretagogue.

Checked against the WADA 2026 Prohibited List. For a specific product and country, Global DRO is the lookup athletes are expected to use — the List names substances, not brand names.

What is in it

Mechanism of action

The blend has no mechanism of its own, but the reasoning behind the pairing is genuine and should be stated fairly before it is qualified. Sermorelin is GHRH(1-29), the shortest fully active fragment of human growth hormone-releasing hormone, acting at the GHRH receptor on pituitary somatotrophs. GHRP-2 is a synthetic agonist at the ghrelin receptor GHS-R1a on the same cells. Two receptors, two signalling routes, one cell, one output.

The synergy is real, more than additive, and demonstrated in humans. Bowers and colleagues showed in normal men in 1990 that GHRH given with a GH-releasing peptide produces a GH pulse substantially larger than either alone, and this has been reproduced across many GHRH/GHRP pairs since. The usual account is that the GHRP arm also suppresses somatostatin tone, so one agent presses the accelerator while the other releases the brake. Of all the pairings on this site, this is the one closest to the drugs the original human synergy work actually used: the classic studies used GHRH or sermorelin with GHRP-2 or GHRP-6.

That said, the synergy studies were acute pharmacology — single doses, GH measured over the following hour, in a laboratory. They establish that a bigger pulse can be produced. They do not establish that producing bigger pulses daily for months changes anything a person would notice. GH output is a surrogate endpoint, and GH research in healthy adults has a long record of failing to convert raised GH into demonstrated clinical benefit.

The component-specific problem here is GHRP-2's endocrine breadth. Unlike ipamorelin, GHRP-2 is not selective. Arvat and colleagues showed in man in 1997 that GHRP-2 raises prolactin, ACTH and cortisol alongside GH, with the ACTH and cortisol response comparable to that of hCRH 2. Ipamorelin was subsequently designed and introduced explicitly as the first GHS that does not do this 4. This matters more than it first appears, because in the GHRP literature the GH response saturates at low doses — around 1 mcg/kg — while the adrenal and lactotroph responses continue to climb with dose. Pushing the GHRP-2 fraction higher therefore buys progressively less extra GH and progressively more cortisol and prolactin. A fixed 1:1 vial is exactly the wrong instrument for managing that trade-off, because the only way to raise sermorelin is to raise GHRP-2 with it.

There is a second, quieter problem with what is in the vial. No registered sermorelin product has existed anywhere since 2008. Whatever a vial labelled 'sermorelin' contains, it is not a licensed medicine and cannot be — it is bulk API from an unverified chain, and unlike tesamorelin there is no marketed reference product to compare it against. Sermorelin is also a straight 29-residue human peptide with no stabilising modifications, so it is the more fragile of the two in solution. Nothing about the withdrawal of Geref makes the grey-market powder equivalent to the drug that was withdrawn.

What the research shows

There is no controlled study of this blend, and no study of any design in which sermorelin and GHRP-2 alone were given together as a fixed mixture. One published human study did administer both at once, and it deserves to be reported accurately rather than either ignored or oversold: Sigalos and colleagues (2017) retrospectively reviewed men on testosterone therapy who had been prescribed GHRP-6, GHRP-2 and sermorelin at 100 mcg each, three times daily 1. That is a three-drug combination, in men simultaneously on testosterone, reviewed retrospectively without a control group, reporting a surrogate endpoint. It cannot isolate what sermorelin plus GHRP-2 does, and it was not designed to.

Research in humans

The closest thing to combination evidence is Sigalos et al., Am J Mens Health 2017: 105 hypogonadal men on testosterone therapy were prescribed the three secretagogues; 14 met the inclusion criteria, and after a mean of 134 days mean IGF-1 rose from 159.5 to 239.0 ng/mL 1. It is a retrospective chart review, uncontrolled, small, confounded by concurrent testosterone, and it measures IGF-1 rather than any clinical outcome. Individually: sermorelin has real trial evidence in its licensed paediatric indication and as a pituitary function test, but essentially none in healthy adults. GHRP-2 has human data as an acute diagnostic stimulus and in small studies in GH-deficient children, including a 1998 study in which prepubertal GH-deficient children received escalating subcutaneous doses over eight months. Arvat et al. (Peptides 1997) characterised its GH, prolactin, ACTH and cortisol effects in healthy adults. The class-level GHRH-plus-GHRP synergy is well established in humans.

Animal and lab research

No animal study of this specific fixed mixture could be located. Both compounds separately produce dose-dependent GH release in rodents, pigs and dogs, and the GHRH-plus-GHRP synergy is reproducible in those species. None of that is evidence about a pre-mixed vendor product.

Caveats. The composition is not standardised. Vials sold under this name include 5 mg / 5 mg and 2 mg / 2 mg, and three-way 9 mg vials combining sermorelin with both GHRP-2 and GHRP-6 are also marketed; there is no agreed ratio because no study has ever compared ratios. The provenance of the sermorelin fraction is unverifiable, with no reference product in existence. Neither compound has long-term human safety data in healthy adults, and there is none at all for the mixture. No research exists in women or older adults. There is no controlled evidence that chronic submaximal GH stimulation benefits healthy people, and material sold as a research chemical is not verified for identity, purity or sterility.

What it is used for

  • Marketed for body composition: more lean mass, less fat mass
  • Marketed for sleep quality, recovery and 'anti-ageing'
  • Used in men's health and wellness practice as a cheaper alternative to growth hormone, often alongside testosterone therapy
  • Used to raise GH and IGF-1 — the only claim with supporting human data, and a surrogate endpoint rather than a clinical outcome. That data belongs to the components separately: GHRP-2's acute GH response was characterised on its own 2, the synergy of a GHRH with a GH-releasing peptide was established in unrelated work 3, and the closest thing to a human report of this kind of pairing is a small uncontrolled series in hypogonadal men 1

Dosing

Dose
User protocols describe volume of reconstituted blend rather than milligrams: typically 0.05-0.15 ml per injection, which from a 5/5 mg vial at a common dilution delivers roughly 100-300 mcg of each component
Frequency
once daily at bedtime, or in the more aggressive protocols two to three times daily with at least three hours between doses; the one published human report used thrice-daily dosing
Route
subcutaneous, into abdominal subcutaneous fat
Duration
cycles of 12-24 weeks are described in user protocols; no research supports any particular duration
  • No approved or validated dose exists for the blend. Every figure here comes from user protocols, vendor pages and former clinic practice, not from a study of the combination.
  • The dose must be expressed as a volume, because one injection delivers both compounds in whatever ratio the vial was filled at.
  • The fixed ratio is a sharper problem here than with a selective GHRP. GHRP-2's GH response saturates at low doses while its ACTH, cortisol and prolactin effects keep rising with dose 2 — the contrast with ipamorelin, which was designed to be free of exactly those effects 4, is the whole reason the choice of GHRP matters — so the sensible way to use it is to stay low. But in a 1:1 vial the only way to increase the sermorelin dose is to increase GHRP-2 in step, which pushes the fraction with the endocrine side effects upward for progressively less additional GH. Buying the two separately preserves the ability to run a higher GHRH dose against a deliberately low GHRP dose. The blend removes it.
  • Attribution is impossible. Cortisol-related effects, prolactin-related effects and hunger have a clear mechanistic home in the GHRP-2 fraction rather than the sermorelin fraction 2, but with a mixture you cannot demonstrate that by reducing one, and stopping means stopping both.
  • Sermorelin doses in the region of 100-300 mcg for adults come from off-label clinic practice, not from the licensed indication, which was 0.03 mg/kg daily in children — and that licence no longer exists, the applications having been withdrawn at the manufacturer's request rather than for reasons of safety or effectiveness 5.
  • GHRP-2 at 100 mcg is roughly the 1 mcg/kg dose used as an acute diagnostic bolus in Japan. Using a diagnostic stimulus as a daily chronic therapy is an extrapolation nobody has validated.
  • Injection on an empty stomach, at least two hours after eating, is advised in protocols because raised insulin and free fatty acids blunt the GH response. That is established GH physiology, not a finding about this product.

These figures describe what the literature and published protocols report. They are not advice and not a dosing instruction.

Protocols

Daily evening injection

user protocol — not validated

Source: User protocols, vendor pages and former clinic practice

This is not a validated schedule. It is a pattern that circulates among users and sellers, reproduced because it is what people actually follow — not because it has been tested. No trial established these doses, this interval or this duration, and nobody is checking what is in the vial. Treat every number below as an assertion, not a finding.

Weeks 1-12 to 240.05-0.15 ml of reconstituted blend once daily at bedtime, subcutaneously, at least two hours after eating
More aggressive protocolstwo to three times daily with at least three hours between doses; the one published human report used thrice-daily dosing

Raising the volume raises both components together, and that is the wrong direction for the GHRP-2 fraction: its GH response saturates at a low dose while its ACTH, cortisol and prolactin effects keep climbing. The sensible way to use GHRP-2 is to stay low, which a fixed-ratio vial does not allow while the sermorelin dose goes up.

Schedules are reproduced as their source states them. Units, IU and milligrams explains why the figures are not interchangeable between products.

Reconstitution

Vial sizes
5/5 mg, 2/2 mg
Solvent
bacteriostatic water (0.9% benzyl alcohol); sterile water only if the vial is used within 24 hours
Storage
Reconstituted at 2-8 °C, protected from light; the customary three to four weeks is a convention rather than a stability finding for this mixture. Lyophilised powder at -20 °C. Do not freeze after reconstitution.

Worked example

A 10 mg vial (5 mg sermorelin + 5 mg GHRP-2) with 2.5 ml bacteriostatic water gives 2 mg/ml of each. 0.1 ml, that is 10 units on a U100 insulin syringe, contains approximately 200 mcg of each component — and there is no way to take more of one without taking more of the other.

Let the water run down the wall of the vial and swirl rather than shake. No stability data have been published for these two peptides in shared solution, and the sermorelin fraction is the more fragile of the two: it is an unmodified 29-residue peptide, and the historical Geref product was supplied as a lyophilised powder with specified handling for that reason. In practice most clinics that used this pairing kept the two in separate vials and drew both into one syringe, which preserves independent dosing; the pre-mixed vial gives that up.

Safety

Side effects

  • Injection site reactions: redness, itching, pain and transient swelling — the commonest complaint in the sermorelin trials
  • Increased appetite, often marked, attributable to the GHRP-2 fraction acting at the ghrelin receptor 2
  • Raised cortisol, ACTH and prolactin: documented for GHRP-2 in humans and dose-dependent 2, and the specific liability that distinguishes this blend from an ipamorelin-based one, ipamorelin having been selected precisely for the absence of those effects 4. Prolactin elevation can in principle cause breast tenderness or gynaecomastia in men and menstrual disturbance in women; this has not been studied over months of use.
  • Water retention, puffiness and joint aches — the classic consequences of raised GH
  • Tingling or numbness in the hands; carpal tunnel-type symptoms with sustained elevation
  • Drowsiness or vivid dreams after bedtime injection
  • Flushing, headache and a transient metallic taste, reported with sermorelin
  • Raised fasting glucose and reduced insulin sensitivity are a recognised consequence of sustained GH elevation, and are not routinely monitored in practice
  • No controlled safety dataset exists for the combination, and none for GHRP-2 as a chronic therapy in healthy adults — the human GHRP-2 literature is built on acute single-dose studies 2 and the one located report of a GHRH/GHRP pairing in men is small and uncontrolled 1

Do not use if

  • Active or previous malignancy. Raising GH and IGF-1 in someone with a current or past malignancy is contraindicated on the same reasoning that governs approved growth hormone therapy; the mechanism here is established rather than speculative.
  • Diabetes or impaired glucose tolerance: GH opposes insulin action and sustained elevation worsens glycaemic control
  • Prolactinoma or unexplained hyperprolactinaemia, and caution with dopamine antagonists — a concern specific to the GHRP-2 fraction, which raises prolactin dose-dependently in humans 2, rather than to the blend as a whole, which is exactly the problem a fixed ratio creates
  • Cushing's syndrome or any condition in which additional cortisol drive is unwelcome — GHRP-2 raises ACTH and cortisol as well as GH 2
  • Untreated hypothyroidism, which blunts the GH response, and active proliferative retinopathy, following the contraindications for approved somatropin
  • Pregnancy and breastfeeding: no data
  • Children and adolescents: sermorelin's licensed use was paediatric, but under specialist endocrine supervision at a defined dose — a grey-market blend is not that, and GHRP-2 has no such standing
  • Competitive athletes under the WADA code: both components are prohibited at all times
  • Anyone who needs to be able to attribute an effect to one component or adjust one dose

Interactions

Never studied for the combination. Mechanistically predictable and, for the GHRP-2 fraction, unusually broad: opposition to insulin and oral glucose-lowering drugs; interaction with corticosteroids, which both suppress the GH axis and compound the cortisol question; altered thyroid hormone replacement requirements, since GH affects peripheral T4 to T3 conversion and untreated hypothyroidism blunts the GH response; blunting by somatostatin analogues such as octreotide; and additive prolactin elevation with dopamine antagonists such as antipsychotics and metoclopramide, given that the GHRP-2 fraction raises prolactin on its own 2. Concurrent testosterone therapy, the setting in which this pairing is most often used in practice, itself raises IGF-1 and confounds any attempt to judge whether the peptides are working. These follow from endocrine physiology rather than from studies of this product.

Sources