There is real human hexarelin dosage data, and it is more interesting than the charts suggest. The compound was studied by four routes at once, and the one long study found its own effect fading.
The short version
The human studies used 0.5 to 2 µg/kg into a vein. Half the peak response came at about 0.5 µg/kg. By mouth, only 0.3% got in. One study ran 16 weeks at 1.5 µg/kg twice a day. The growth hormone response nearly halved.
Hexarelin is a six-residue growth hormone secretagogue, and it was studied properly in the mid-1990s in a way most compounds in this library never were. The results are the reason it is not a drug.
What the hexarelin studies administered
| Study | Species | Dose | Route | Duration | n |
|---|---|---|---|---|---|
| Imbimbo et al., 1994 | Human (healthy adult males) | 0.5, 1 and 2 µg/kg | Intravenous bolus | Single doses | 12 |
| Ghigo et al., 1994 | Human (healthy young volunteers) | 1 and 2 µg/kg IV; 1.5 and 3 µg/kg SC; 20 µg/kg intranasal; 20 and 40 mg oral | Four routes compared | Single doses | 12 |
| Arvat et al., 1994 | Human (young and elderly males) | 2 µg/kg | Intravenous | Single doses | 29 |
| Rahim et al., 1998 | Human (healthy elderly) | 1.5 µg/kg | Subcutaneous, twice daily | 16 weeks | 12 |
| Xu et al., 2005 | Rat (pressure-overload heart failure) | 100 µg/kg | Subcutaneous, twice daily | 3 weeks | — |
| Zambelli et al., 2021 | Rat (acute lung injury) | 320 µg/kg | Intraperitoneal, single dose | Single | — |
A dash means we have no sourced figure for that cell and have not estimated one.
Every confirmed figure here is in micrograms per kilogram. If you meet a hexarelin dose written in milligrams per kilogram, check it — a thousand-fold unit slip is the most likely explanation.
The route study nobody quotes
Ghigo and colleagues gave the same 12 volunteers hexarelin four ways in one study: intravenous, subcutaneous, intranasal and oral. That design is rare and it settled the route question in a single paper.
- Subcutaneous: 77% biological bioavailability. Effectively as good as intravenous.
- Intranasal: 4.8%. Usable, but about sixteen times weaker.
- Oral: 0.3%. Which is why the oral arms needed 20 and 40 milligrams to do what 2 micrograms per kilogram did in a vein.
Biological bioavailabilities were 77.0 +/- 10.5%, 4.8 +/- 0.9%, and 0.3 +/- 0.1% for the sc, intranasal, and po routes, respectively.
Ghigo et al., Journal of Clinical Endocrinology and Metabolism, 1994Anything sold as oral hexarelin runs into that 0.3% figure. It is the cleanest route-of-administration data in this entire library, and it is thirty years old.
This is what a properly studied compound looks like, and it is rare here. One paper, one group of volunteers, four routes, a bioavailability number for each. Most compounds in this library have never had their route question answered at all — the arguments about topical versus injectable GHK-Cu, or oral versus injected BPC-157, exist because nobody ran this study for them.
Research compounds with lot-matched testing
Third-party tested research compounds, each shipped with a batch-matched certificate of analysis showing HPLC purity and mass-spec identity — the documentation this site argues you should hold any supplier to.
What 16 weeks did
Rahim and colleagues gave 12 healthy elderly volunteers 1.5 µg/kg subcutaneously, twice daily, for 16 weeks. This is the only chronic human hexarelin exposure on record.
The growth hormone response fell steadily. Area under the GH curve went from 19.1 at baseline to 13.1 at week 1, 12.3 at week 4 and 10.5 at week 16 — then back to 19.4 four weeks after stopping.
Serum IGF-I and IGF binding protein-3 did not change significantly over the 20-week period.
Rahim et al., Journal of Clinical Endocrinology and Metabolism, 1998A secretagogue that raises GH acutely, loses about half that response over four months, and never moves IGF-I is a specific and useful finding. It is also the finding most hexarelin write-ups leave out.
Hexarelin is not an approved drug
We checked the FDA's drug approval database and found no hexarelin record. We checked the clinical-trials registry and found no registered interventional study.
A 2012 analytical-chemistry paper puts it plainly, grouping hexarelin with the other growth hormone releasing peptides as non-approved pharmaceuticals that are nonetheless readily available online. It is also on the World Anti-Doping Agency's prohibited list.
- No FDA record under the name hexarelin, in either the generic or brand field.
- No registered interventional trial listing hexarelin as an intervention.
- Banned in sport, alongside the rest of the growth hormone secretagogue family.
What if you already have a number?
Hexarelin figures are per kilogram and in micrograms, which is the range where vial-to-syringe arithmetic goes wrong most often.
Turning a figure into a syringe volume is arithmetic, and the peptide calculator does it from the vial strength and the volume of diluent. That part always works.
Which is the trap. A calculator converts an unsourced number as cleanly as a sourced one. The output looks equally precise either way.
How it compares in the class
Hexarelin is the most potent secretagogue in the ghrelin-mimetic family and the fastest to lose its effect. Ipamorelin, by contrast, has one human trial at 0.03 mg/kg twice daily that missed its endpoint, and CJC-1295 works through a different receptor entirely.
See ipamorelin dosage, the CJC-1295 and ipamorelin figures, the hexarelin complete guide and where to buy hexarelin. The peptide dosage chart holds the whole library.
Research compounds with lot-matched testing
Third-party tested research compounds, each shipped with a batch-matched certificate of analysis showing HPLC purity and mass-spec identity — the documentation this site argues you should hold any supplier to.
What to know now
- Human hexarelin doses are 0.5 to 2 µg/kg, with a half-maximal GH response near 0.5 µg/kg in 12 healthy men.
- Bioavailability by route: 77% subcutaneous, 4.8% intranasal, 0.3% oral.
- Sixteen weeks at 1.5 µg/kg twice daily cut the GH response from 19.1 to 10.5, and it recovered after stopping.
- IGF-I and IGFBP-3 did not change over 20 weeks.
- No FDA record, no registered interventional trial, and a place on the WADA prohibited list.
- Every confirmed animal dose is also in micrograms per kilogram.
What we're watching
Nothing much, honestly, and that is the finding. Hexarelin's human program ran, the desensitization result landed, and development stopped. The current literature is cardiac and neuroprotective work in rodents rather than anything aimed at a dose.
If a group ever repeats the 16-week study with a different schedule, that would be the interesting one — the open question is whether intermittent dosing avoids the fade.
Frequently asked questions
What dose of hexarelin was used in humans?
Micrograms per kilogram. The dose-response study used 0.5, 1 and 2 µg/kg as intravenous boluses in 12 healthy men, and reported a half-maximal growth-hormone response at about 0.5 µg/kg.
Does hexarelin work by mouth?
Barely. The four-route study measured biological bioavailability of 77% subcutaneous, 4.8% intranasal and 0.3% oral. Oral doses had to be 20 to 40 mg to do anything at all.
What happened in the long hexarelin study?
The growth-hormone response fell. Twelve elderly volunteers took 1.5 µg/kg twice daily for 16 weeks; the GH area under the curve dropped from 19.1 to 10.5, and IGF-I did not change. Four weeks after stopping it had recovered.
Is hexarelin approved anywhere?
There is no record of hexarelin in the FDA's drug approval database and no registered interventional trial. A 2012 analytical paper groups it with the non-approved growth hormone releasing peptides.
What doses did the hexarelin animal studies use?
Also micrograms per kilogram. The rat heart-failure work used 100 µg/kg twice daily for three weeks, and the pharmacokinetic study used 5 to 50 µg/kg.
References
- Imbimbo, B. P., Mant, T., Edwards, M., et al. (1994). Growth hormone-releasing activity of hexarelin in humans: A dose-response study. European Journal of Clinical Pharmacology, 46(5), 421–425. https://doi.org/10.1007/BF00191904
- Ghigo, E., Arvat, E., Gianotti, L., et al. (1994). Growth hormone-releasing activity of hexarelin, a new synthetic hexapeptide, after intravenous, subcutaneous, intranasal, and oral administration in man. Journal of Clinical Endocrinology and Metabolism, 78(3), 693–698. https://doi.org/10.1210/jcem.78.3.8126144
- Arvat, E., Gianotti, L., Grottoli, S., et al. (1994). Arginine and growth hormone-releasing hormone restore the blunted growth hormone-releasing activity of hexarelin in elderly subjects. Journal of Clinical Endocrinology and Metabolism, 79(5), 1440–1443. https://doi.org/10.1210/jcem.79.5.7962341
- Rahim, A., O'Neill, P. A., & Shalet, S. M. (1998). Growth hormone status during long-term hexarelin therapy. Journal of Clinical Endocrinology and Metabolism, 83(5), 1644–1649. https://doi.org/10.1210/jcem.83.5.4812
- Xu, X. B., Pang, J. J., Cao, J. M., et al. (2005). GH-releasing peptides improve cardiac dysfunction and cachexia and suppress stress-related hormones and cardiomyocyte apoptosis in rats with heart failure. American Journal of Physiology — Heart and Circulatory Physiology, 289(4), H1643–H1651. https://doi.org/10.1152/ajpheart.01042.2004
- Thomas, A., Delahaut, P., Krug, O., Schänzer, W., & Thevis, M. (2012). Metabolism of growth hormone releasing peptides. Analytical Chemistry, 84(23), 10252–10259. https://doi.org/10.1021/ac302034w
- Zambelli, V., Rizzi, L., Delvecchio, P., et al. (2021). Hexarelin modulates lung mechanics, inflammation, and fibrosis in acute lung injury. Drug Target Insights, 15, 26–33. https://doi.org/10.33393/dti.2021.2347
- World Anti-Doping Agency. The Prohibited List 2026. https://www.wada-ama.org/en/prohibited-list
- Sigalos, J. T., & Pastuszak, A. W. (2018). The safety and efficacy of growth hormone secretagogues. Sexual Medicine Reviews, 6(1), 45–53. https://doi.org/10.1016/j.sxmr.2017.02.004
The absence of an approval was checked against the FDA's drug approval database and the clinical-trials registry directly.