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MuscleLimited human evidence

Hexarelin

Synthetic hexapeptide growth-hormone secretagogue developed in the 1990s. Stimulates GH release potently in short-term human studies. Concerns about tachyphylaxis (tolerance) with chronic use have limited clinical development.

Educational only — not medical advice. SmartPeptide does not prescribe, diagnose, or treat. Always consult a licensed healthcare provider before using any peptide, supplement, medication, or protocol.

What the research shows

1990s/2000s short-term studies show robust GH/IGF-1 elevation in healthy adults. Some research interest in cardiac protection (preclinical). No modern Phase 3 trials in humans. Not pursued to FDA approval.

What's still experimental

Tachyphylaxis management, optimal cycling protocols, long-term safety, and any modern indication-specific human RCTs.

Anecdotal / community reports

Bodybuilding and 'optimization' communities use hexarelin in cycles. Reports of strength/recovery improvements are uncontrolled and confounded by other interventions.

Anecdotal reports are NOT scientific evidence. They reflect personal experience and may not generalize.

FDA approval status

Source: openFDA + DailyMed (NIH/NLM)
No FDA-approved drug label exists for “Hexarelin”. This peptide is not currently approved by the FDA as a finished pharmaceutical product. Any commercial product claiming FDA approval should be treated with suspicion.

Doses studied in research

Source: Published clinical trial

What published trials tested or FDA-approved labels specify. Reporting research facts — not a SmartPeptide recommendation.

Community-anecdotal range — NOT a SmartPeptide recommendation

The doses below are aggregated from research-peptide community forums (Reddit, biohacker discussions). They are NOT supported by clinical trials, NOT FDA-approved, and NOT a SmartPeptide recommendation. Source purity, dose accuracy, and user-reported outcomes are unverifiable. We display this only because the information is publicly available elsewhere — visitors should absolutely consult a licensed clinician familiar with experimental peptides before any use.

Community-anecdotal — not evidence-basedBodybuilding + performance community forums
Indication studied: Community-discussed for GH stimulation (1990s research; not pursued clinically due to tachyphylaxis)
Typical
100µg
1-3x daily · subcutaneous

Most-discussed range

Open calculator
Maximum
200µg
1-3x daily · subcutaneous

Higher community range

Open calculator

Notes from the source: Tachyphylaxis (diminishing response) is well-documented and limits long-term use. Most users cycle 4 weeks on / 4 weeks off.

Important framing: The numbers above are what published trials tested or what FDA-approved labels specify. They are NOT a SmartPeptide recommendation for you. Trial doses come paired with screening, monitoring, and clinician oversight. Always consult a licensed clinician before any peptide use.

How clinicians typically protocol this

Third-party reference · not our recommendation

Dosing phases, cycle lengths, and administration timing as listed in a compounding-pharmacy clinician reference guide. Shown so you can see what a real protocol looks like — and bring informed questions to a licensed clinician.

Third-party protocol referenceCompounding-pharmacy clinician protocol reference (Nov 2025)

Dose numbers, frequencies, and cycle lengths in this panel are extracted from a clinician-facing reference protocol distributed by a US-based compounding pharmacy in November 2025. SmartPeptide has paraphrased all descriptive text and adds no endorsement. Always consult a licensed clinician.

Growth Hormone

Potent synthetic GHRP; strong GH pulse with tolerance concerns at higher doses.

Protocol phases

Typical
100–200 µg1–3× daily
subcutaneous

pre-workout, before bed, or morning

Cycle length

Short cycles (4–6 weeks) with extended off periods to avoid receptor desensitization.

Administration timing

Fasted state preferred. Carbs and fat blunt GH pulses.

Reported side effects
Rise in cortisol and prolactin at higher dosesWater retention
Reconstitution calculator Storage & reconstitution guide
Not medical advice. SmartPeptide does not prescribe, diagnose, or treat. The protocol above reproduces dose figures from a third-party clinician reference so you can see what compounding-pharmacy guidance typically looks like — it is not a recommendation for you, and it has not been validated against peer-reviewed dose-ranging trials. Many of these compounds are not FDA-approved for human use. Work with a licensed clinician familiar with peptide therapy before considering anything here.

FDA enforcement & recalls

Live · openFDA Drug Enforcement API
No FDA enforcement actions (recalls, market withdrawals, safety alerts) on record for “Hexarelin”. This is the expected baseline for most peptides — the absence of recalls does NOT imply general safety, only that no formal FDA enforcement has been initiated against approved formulations.

Mechanism & targets

ChEMBL · UniProt · Open Targets

Molecule (ChEMBL)

View on ChEMBL
Formula
C59H72N14O9

Live research

PubMed · ClinicalTrials.gov · Europe PMC · OpenAlex
PubMed papers
0
total
Human studies
0
MeSH: humans
Clinical trials
0
published
Active trials
0
0 total registered
No live research records found via PubMed or ClinicalTrials.gov for this query.

Europe PMC — 567 additional records

Includes EU/UK studies and PubMed Central full-text articles. Often surfaces research weeks before PubMed indexes it.

Research volume (OpenAlex topic graph)

Total works
1,264
all years
Last 5 years
259
recent activity
Open access
941
freely readable
OA share
74%
of all works

Human clinical evidence

Semantic Scholar · AI TLDRs · influence-ranked
Semantic Scholar API is currently rate-limited.

Human-study summaries for “hexarelin” are available on Semantic Scholar but the shared free-tier API quota is exhausted right now. Try refreshing in a few minutes, or check the PubMed and Europe PMC panels above for the same literature.

Research funding & verification

NIH RePORTER · CrossRef DOI registry

NIH-funded research

U.S. National Institutes of Health
Funded projects
8
all years
Top award sum
$2.6M
aggregate USD
Years covered
12
research span
Largest active / recent grants

Publication landscape

CrossRef · DOI registry
Indexed works (CrossRef)
209
all DOIs registered
Retracted papers
0
no retractions on record
Top funders of indexed research
  • University of Queensland3 works
  • National Health and Medical Research Council3 works
  • Università degli Studi di Milano-Bicocca2 works
  • National Natural Science Foundation of China2 works
  • Ministero dell’Istruzione, dell’Università e della Ricerca2 works
  • Australian Postgraduate Award2 works

Funder diversity is a credibility signal. Research concentrated in a single drug company's funding warrants more scrutiny than research funded across NIH, charities, and academic grants.

Preprints — cutting edge

bioRxiv · medRxiv · via Europe PMC

Preprints have NOT been peer-reviewed. They are early research shared by authors before formal validation. Treat findings as preliminary.

Showing 2 of 2 preprints indexed by Europe PMC.

Known risks

Tachyphylaxis (diminishing response with continued use) is well-documented. Theoretical cortisol and prolactin elevation. Cardiac effects (mostly positive in animal models) but human data is sparse. Source quality is a major concern — no FDA-approved formulations.

Reported side effects

Injection-site reactions, transient flushing, mild dizziness, possible water retention. Long-term effects poorly characterized in modern trials.

FDA adverse event reports (FAERS)

Updated quarterly by FDA
Reports filed
1
FAERS, all years
Serious reports
0
0% of reports
Top reporting countries
  • US1

Most-reported reactions

  • Insomnia
    1
  • Night Sweats
    1

Counts from FDA Adverse Event Reporting System (FAERS). Voluntary reports — they show what was reported, not whether the drug caused the event. Many reports lack confirmation. FAERS docs

What requires medical supervision

Not FDA-approved for any indication. Discuss with a clinician familiar with experimental peptides before considering. Source purity verification is essential.

Questions for your clinician

  • Are there evidence-based alternatives (sermorelin, tesamorelin) that would address my goal?
  • How would we monitor for tachyphylaxis and metabolic side effects?
  • What's the exit criteria?

Editorially curated references

Discussions about Hexarelin

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