Why does hexarelin stop working?

Sustained activation of the growth hormone secretagogue receptor downregulates it. Human studies measured the growth hormone response falling substantially after around two weeks of daily use. It is a receptor property — not a batch problem — and a higher dose does not fix it.

Is it better than GHRP-2?

It releases more growth hormone per dose. It also raises cortisol and prolactin more, and it desensitises. For anything longer than a couple of weeks, potency per dose is the wrong thing to optimise for.

What is the CD36 cardiac effect?

Hexarelin binds a receptor on heart tissue that has nothing to do with growth hormone, and animal work suggests protective effects after cardiac ischaemia. It is a legitimate research direction and it has not been established in humans.

Muscle & performanceAnti-aging & longevity

Hexarelin

Examorelin · EP-23905

Early human trialsProhibited in sportReviewed 16 Aug 2026

Hexarelin is a close structural relative of GHRP-6, one methyl group apart, and it releases more growth hormone per dose than any other peptide in this family. On potency alone it is the strongest option available.

It also has a documented problem the others do not, and it is the reason this page exists in the shape it does: the growth hormone response attenuates with continuous use. Human studies have measured this directly, with the response substantially reduced after around two weeks of daily dosing. This is not a tolerance people speculate about on forums; it was found in the clinical literature and it is why hexarelin never became a long-term treatment.

Its other distinctive property is a direct cardiac effect, mediated through the CD36 receptor, not the growth hormone axis. That is a real and interesting research thread, since hexarelin appears to act on heart tissue independently of growth hormone. It also remains preclinical and early-phase, and it is not what the compound is sold for.

How it works

Hexarelin activates the growth hormone secretagogue receptor, releasing growth hormone and suppressing somatostatin. Same mechanism as its relatives, with greater potency at the receptor.

The desensitisation is the mechanistically important part. Sustained agonism of this receptor downregulates the response, and with hexarelin that happens fast enough to be measured within a fortnight. Intermittent use is described for exactly this reason, though no study has established a schedule that avoids it.

Cortisol and prolactin rise more with hexarelin than with the other GHRPs, consistent with its potency at the receptor and its lack of selectivity.

Separately, hexarelin binds CD36 on cardiac tissue and vasculature. This is a growth-hormone-independent action, demonstrated in animals and in early human cardiac work, and it is the basis of the cardioprotection research around this compound.

Quick reference

Commonly described dose: 100 mcg–200 mcg
How often: Once or twice daily in study conditions
Route: Subcutaneous
Where: Abdomen, Thigh, Upper arm
Timing: Most often described on an empty stomach.
Half-life: About 55 minutes
Storage once mixed: Refrigerated, 30 days
Cycle: About 2 weeks on, At least 2 weeks off

These describe what sources report, not what you should do. Full detail and provenance in the dosing section below.

Price index

Per-milligram pricing across vendors arrives with the directory. We are recording prices now so the history exists when the page ships.

Vocabulary on this page

GHRH analogue: A synthetic version of the hormone that tells the pituitary to release growth hormone. One of the two receptor routes into a growth hormone pulse.
Secretagogue: A substance that makes the body release something it already produces, rather than supplying that thing from outside.
Evidence level: The category of human evidence behind a compound, from preclinical through to approved. Stated on every profile here as a category, not an adjective.
Peptide: A short chain of amino acids: the same building blocks as a protein, in a chain short enough to behave differently.

The whole glossary →

Regulatory status — United States

Not approved for human use in any jurisdiction. Reached early-phase clinical study in the 1990s; development did not continue, in part because the growth hormone response was not sustained. Sold only as a research chemical.

Last reviewed 16 Aug 2026. Regulatory positions in this category change frequently; we date this line so you can see how current it is.

What it is studied for

Each entry states the evidence behind it. We do not rank indications by effectiveness — for most compounds here, that would be a claim nobody can support.

Raising growth hormone

Clinical trial

The most potent effect in the class, on a single-dose basis.

EvidenceWell documented in human pharmacology studies, and equally well documented to attenuate with continued use.

Cardiac protection

Published review

A growth-hormone-independent effect through the CD36 receptor.

EvidenceAnimal studies and small early human cardiac work. Not established as a treatment, and no phase 3 programme exists.

Identity and clearance

Molecule

Class: Synthetic hexapeptide, growth hormone secretagogue
Molecular weight: 887.04 Da
Length: 6 amino acids

Sequence

His-D-2-methyl-Trp-Ala-Trp-D-Phe-Lys-NH2

A single methyl group distinguishes it from GHRP-6, and accounts for the difference in potency.

Pharmacokinetics

Clinical trial

Peak0.3 h

Half-life0.9 h

Substantially cleared5 h

Modelled from the half-life above, assuming first-order elimination. Illustrative rather than measured — it shows the shape of clearance, not a prediction for any individual.

The half-life describes the peptide, not the effect. The growth hormone response it produces diminishes over days to weeks of continuous use, which no pharmacokinetic figure captures.

Dose protocols reported in sources

Displayed for reference only. Every row says where it came from, and a trial protocol and a community convention are not the same kind of information. None of this is fed into the calculator, and none of it is a recommendation.

Dose protocols reported in sources, with the source of each.
Goal	Dose	Frequency	Route	Units, 2 mg vial	Source	Start this protocol
Growth hormone response, as studied	100 mcg – 200 mcg	Once or twice daily in study conditions	SubcutaneousAround 1.5–2 mcg per kilogram. Note that the studies using this range are the same ones that measured the response fading.	10–20 u	Clinical trial	Start this
Commonly described community protocol	100 mcg – 200 mcg	One to two times daily, in short blocks rather than ongoing	SubcutaneousCommunity sources describe limiting use to short runs specifically because of desensitisation. That is a sensible response to a documented problem, but no study establishes how long an off period needs to be to restore the response.	10–20 u	Community practice	Start this

Start this copies a row into a protocol of your own, which you can then edit. Where a source gave a dose range or an ambiguous frequency, those fields arrive empty — we will not pick a number on your behalf.

CheckRows marked community practice describe what people commonly do, drawn from public discussion. They are not derived from any trial and are not evidence that a dose is safe or effective.

Cycling

Community practice

About 2 weeks on, At least 2 weeks off.

Unlike most cycling conventions on this site, this one has a documented reason behind it: the growth hormone response is measurably attenuated after roughly two weeks of continuous dosing. What is not documented is how long an off period restores it. The two-week figure is convention.

Calculator

Work out what to draw

Pre-filled with a 2 mg vial as a worked example. These are not recommended values — change them to match the vial in front of you.

Draw to 10 units on a 1 mL U-100 syringe. That is 0.1 mL, containing 100 mcg of Hexarelin.

Concentration1mg / mL

Volume drawn0.1mL

Doses per vial20doses

Per unit10mcg / unit

10 units sits exactly on a printed line.

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Bioalmanac performs arithmetic on values you enter. It does not recommend doses, schedules or compounds, and nothing here is medical advice. Confirm every calculation against your vial and syringe before drawing, and speak with a licensed healthcare provider.

Open this calculation in the full calculator

Units, concentration, bacteriostatic water — the glossary defines the vocabulary, and a unit is not a fixed volume.

Safety

Reported effects

Diminishing growth hormone response over about two weeksClinical trial
Documented in human studies
The characteristic problem with this compound. Raising the dose does not restore it.
Rise in cortisol and prolactinClinical trial
Measured in human studies
The largest of the three GHRPs on this site, consistent with its potency at the receptor.
Increased hungerCommunity practice
Commonly reported
Present, and generally milder than with GHRP-6.
Water retention and puffinessCommunity practice
Commonly reported
Tingling or numbness in the handsCommunity practice
Occasionally reported
Reduced insulin sensitivityPublished review
Expected from raised growth hormone

When to stop

Numbness, tingling or persistent pain in the hands or wrists.
Swelling that does not settle, particularly in the ankles or face.
Rising fasting glucose, or new thirst, frequent urination or blurred vision.
Nipple tenderness or discharge, or a change in menstrual cycle. Cortisol and prolactin rise more with this compound than with its relatives.
Any allergic response: rash, hives, facial swelling or difficulty breathing. Seek urgent care.
Any new lump, unexplained weight loss or unexplained persistent pain.

Interactions and situations that need care

Active or previous cancerAvoid
Growth hormone and IGF-1 are proliferative signals, and no evidence supports raising them deliberately in someone with malignancy.
Diabetes or impaired glucose toleranceUse caution
Growth hormone opposes insulin, and the cortisol rise with hexarelin adds to that. Blood glucose should be monitored rather than assumed.
Existing cardiovascular diseaseUse caution
Hexarelin has direct cardiac activity through CD36, separate from growth hormone. In healthy hearts that has been of research interest; in a diseased heart the consequences are simply unstudied, and 'unstudied' is not the same as 'benign'.
Competing in a tested sportAvoid
Growth hormone secretagogues are named explicitly in WADA's S2 category and are prohibited at all times, in and out of competition. Whether a current test detects this particular compound is beside the point — the prohibition is on the substance, not on being caught.
Pregnancy and breastfeedingAvoid
No reproductive or developmental safety data.

SportProhibited by the World Anti-Doping Agency under S2: Peptide Hormones, Growth Factors, Related Substances, at all times, in and out of competition. Growth hormone secretagogues are named explicitly in S2. Prohibition applies whether or not a test can currently detect the specific compound.

What to expect

HonestlyThere is no human efficacy data for this compound, so there is no evidence-based timeline to give. Any site publishing a week-by-week schedule of expected effects has invented it.

It produces the largest growth hormone pulse in the class per dose. That much is well established.
It will stop doing so. The response is measurably reduced after about two weeks of continuous use, and this is the single most important thing to know before buying it.
Increasing the dose does not restore the response. That is not how receptor desensitisation works, and doing it only raises the cortisol and prolactin effects.
Cortisol and prolactin rise more than with GHRP-2 or ipamorelin.
The cardiac research is genuine and interesting, and is not a reason to take it. It is preclinical and early-phase work about a different mechanism.

Storage and handling

Freeze-dried powder: Refrigerated at 2–8 °C, protected from light.
After mixing: Refrigerated at 2–8 °C. Do not freeze once mixed.
Long-term, frozen: Unopened powder is stable at −20 °C or colder.

Printable one-pager How to reconstitute a vial, step by step

With other peptides

CJC-1295synergistic
A GHRH analogue works through a different receptor and produces a larger combined pulse. It does not prevent hexarelin's desensitisation, which is a property of the ghrelin receptor rather than of the pairing.
GHRP-2caution
Same receptor. Running two GHRPs together stacks the side effects and, with hexarelin in the mix, the desensitisation as well.
GHRP-6caution
Same receptor, near-identical structure. There is no mechanistic reason to combine them.
Ipamorelincaution
Both are ghrelin receptor agonists. Ipamorelin's selling point is selectivity, and pairing it with the least selective compound in the class removes the reason to have chosen it.

Check this against a whole stack

Checking your vial

Research chemicals carry no manufacturing standard, so what the vial looks like is often the only quality signal available before you use it. More on assessing quality and COAs.

White cake, clear solution
Standard for a short hexapeptide.
Collapsed, melted or fused cake
Heat exposure in transit. Refrigerating it afterwards does not undo the damage.
Cloudy solution or visible particles after gentle mixing
Degraded or contaminated. Do not use it.

Questions

Why does hexarelin stop working?: Sustained activation of the growth hormone secretagogue receptor downregulates it. Human studies measured the growth hormone response falling substantially after around two weeks of daily use. It is a receptor property — not a batch problem — and a higher dose does not fix it.
Is it better than GHRP-2?: It releases more growth hormone per dose. It also raises cortisol and prolactin more, and it desensitises. For anything longer than a couple of weeks, potency per dose is the wrong thing to optimise for.
What is the CD36 cardiac effect?: Hexarelin binds a receptor on heart tissue that has nothing to do with growth hormone, and animal work suggests protective effects after cardiac ischaemia. It is a legitimate research direction and it has not been established in humans.

References

Attenuation of the growth hormone response to hexarelin during continuous administration
Clinical endocrinology literature, 1997 · Human pharmacology study with repeated dosing
Healthy adults · 1.5–2 mcg/kg subcutaneous, daily · Up to 16 weeks, with responses measured over time
The growth hormone response was substantially reduced after approximately two weeks of continuous daily dosing and did not recover while dosing continued. Cortisol and prolactin rose concurrently.
Hexarelin, CD36 and cardiac effects independent of growth hormone
Cardiovascular research literature, 2010 · Animal studies with limited early human cardiac work
Rodents, with small human cardiac studies
Identified binding to CD36 on cardiac tissue and reported protective effects in animal ischaemia models independent of the growth hormone axis. Human evidence remains limited to small early studies.
Commonly reported community protocols
Bioalmanac editorial summary of public community sources, 2026 · Not a study
Records the short-block dosing pattern described in public discussion as a response to desensitisation. The off-period lengths described are convention, not findings.

Related compounds

CJC-1295

A GHRH analogue that raises growth hormone by amplifying the body's own release signal. Sold in two forms whose durations differ by two orders of magnitude.

GHRP-2

A growth hormone releasing peptide approved in Japan as a diagnostic agent. It triggers a pulse of your own growth hormone rather than supplying any.

GHRP-6

The oldest of the growth hormone releasing peptides, and the one with the strongest effect on hunger. That appetite stimulation is the defining fact about it.

Ipamorelin

A selective growth hormone secretagogue that prompts a short pulse of GH release. Widely used, and supported almost entirely by early pharmacology rather than outcome trials.

Keep this page honest

If something here is wrong, out of date, or missing a source, tell us and we will fix it and say that we did.

Suggest a correction

This page is educational. It describes what published research reports, not what you should do. Peptides discussed here are largely not approved for human use, and nothing on Bioalmanac is medical advice. No clinician reviews these pages.

Page last updated 16 Aug 2026