PepRank

FGL

43%positive1 reports

Also: FGLL · NCAM-derived FG-loop peptide

ExcludedMemoryNasal / Injection

NCAM mimetic that activates FGF receptors; rodent memory data only.

EVYVVAENQQGKSKA · NCAM FG-loop peptide; commonly used as a dendrimer (FGLL) (15 residues)

EVYVVAENQQGKSKA NCAM FG-loop peptide; commonly used as a dendrimer (FGLL)

#46 of 61 research peptides · updated
Onset
Unknown; there are no user reports of a felt effect.
Lasts
Plasma levels were detectable for 1-4 hours after 100-200 mg intranasal in the phase-1 study; nothing is known about how long any effect lasts.
Access
Grey market
Cost / month
No meaningful figure: the phase-1 doses (25-200 mg per dose) would cost far more than other research peptides at vendor prices.
1 user reports
Nothing 1
  • r/neuro· · 1 upvotesOriginal ↗

    The HA - FGL isn't working but I stumbled across another supplement that could work, D - Serine.

    Nothing

    persistent psychosis and cognitive loss after chronic solvent abuse; HA-FGL (hyaluronic-acid-conjugated FGL)

Strict case
Agonist of the mitogenic FGF receptor, with only phase-1 data and no users to learn from.
Users report
No meaningful user base for cognitive use. Note: 'FLGR-242' discussed on Reddit is an unrelated myostatin-targeting product, not FGL.
Best effects
None reported in humans
Downsides
Unknown
Watch
Direct FGF-receptor agonist: FGFR signalling is mitogenic and implicated in several cancers · only a phase 1 tolerability/PK study in healthy volunteers; the EU development programme went no further
Evidence
Small human studies — Phase 1 safety/PK only; plus animal
Typical use
No established community dose.
Getting it
Never marketed; development stopped after phase 1. A few research-peptide vendors list FGL or HA-FGL (hyaluronic-acid-conjugated) of unverified identity.

User reports 1

  • r/neuro· · 1 upvotesOriginal ↗

    The HA - FGL isn't working but I stumbled across another supplement that could work, D - Serine.

    Nothing

    persistent psychosis and cognitive loss after chronic solvent abuse; HA-FGL (hyaluronic-acid-conjugated FGL)

Safety

Tier by safety barStrict ExcludedBalanced CautionEvidence only Caution

Seen harmMechanismData gapSilent harmProduct

Seen harm 0/3
The one phase 1 study (24 men, single doses) saw only nasal burning and watery eyes, and only one first-hand report exists, so this zero reflects almost no exposure. 2007 phase 1: single intranasal doses of FGLL in 24 healthy men (PubMed 17375985) ↗
Mechanism 2/3
An NCAM-derived agonist of FGF receptors, whose signalling is mitogenic and drives several cancers; no study has shown harm from FGL itself. Neiiendam et al. 2004: FGL is an NCAM-derived FGF-receptor agonist (PubMed 15525346) ↗
Data gap 2/3
One single-dose phase 1 in 24 healthy men; no repeat-dose human data, and development stopped there. 2007 phase 1: single intranasal doses of FGLL in 24 healthy men (PubMed 17375985) ↗
Silent harm 3/3
Mitogenic tumour promotion would be silent and delayed.
Product 2/3
Rare grey-market nasal or injectable vials of unverified identity, sometimes hyaluronic-acid-conjugated.
Never if
Active cancer or a history of cancer · Pregnancy or breastfeeding (no human reproductive data)

Studies 5

Sources 2

More in Neuroprotection & repair all 10 →

  1. 1ARA-290 QEQLERALNSS (11 residues) Caution Injection≈ €180–630 / month56%positive40 reportsNon-erythropoietic EPO-derived peptide for small-fibre neuropathy pain.
  2. 2Cortexin Caution Injection≈ €36–90 / month50%positive20 reportsRussian brain-cortex extract, Cerebrolysin cousin; 10-day IM courses.Animal-brain extract given by injection: immune/allergic and theoretical prion risk, and it shares Cerebrolysin's SAE signal.
  3. 3P21 (P021) DGGL (4 residues) Caution Nasal / Oral / Injection≈ €45–180 / month43%positive15 reportsCNTF-derived neurogenic peptide from Alzheimer's mouse work; grey market only.No human safety data; deliberately drives neurogenesis via a growth-factor pathway, and products are of uncertain identity.
  4. 4NAP / Davunetide NAPVSIPQ (8 residues) Clean Nasal2/10estimateADNP-derived microtubule-stabilising peptide; safe in a large trial but ineffective.
  5. 5Dihexa YI (2 residues) Excluded Oral / Topical / Injection≈ €13–53 / month50%positive30 reportsAngiotensin-IV analogue claimed as potent synaptogenic; hyped, not evidenced in humans.Activates the oncogenic HGF/c-Met pathway, has no human safety data, and its foundational studies are under expressions of concern.
  6. 6Humanin MAPRGFSCLLLLTSEIDLPVKRRA (24 residues) Excluded Injection43%positive1 reportsMitochondrial-derived cytoprotective peptide; anti-Alzheimer's in animals only.Its anti-apoptotic action helps glioma cells survive chemotherapy in animal studies, and there is no human data.
  7. 7Cerebrolysin Excluded Nasal / Injection / IV≈ €140–540 / month40%positive29 reportsPig-brain peptide mix for stroke/TBI; strong anecdotes, real safety questions.Cochrane found more non-fatal serious adverse events than placebo; animal-derived injectable with allergy/immune reaction risk.
  8. 8Corticotropin (repository ACTH gel) Excluded Injection43%positive15 reportsPituitary hormone gel approved for MS relapses; works like steroids, costs like a luxury car.Drives the adrenals to flood the body with cortisol, so it carries the corticosteroid label warnings (infection, Cushing's syndrome, adrenal insufficiency on withdrawal, GI perforation, psychosis, high blood pressure and glucose, bone loss) plus anaphylaxis. A prescription relapse treatment under a neurologist, not something to take outside one.
  9. 9Glatiramer acetate Excluded Injection37%positive24 reportsApproved MS drug made of random myelin-mimicking peptide chains; modest relapse cut, injection burden.Prescription immunomodulator for relapsing MS with an FDA boxed warning for anaphylaxis (82 cases, 6 deaths reported to 2024, some years into treatment), plus label warnings for liver injury and skin necrosis. Worth it for MS under a neurologist; not a self-directed peptide.

Sequence beads

Each bead is one amino acid in the peptide's chain, coloured by its side chain: grey for non-polar, cyan for polar, blue for positively charged and fuchsia for negatively charged. Length and mix tell related peptides apart at a glance, from a two-residue dipeptide like carnosine to a 43-residue protein like thymosin beta-4. The colours describe chemistry only and predict neither effect nor safety.

non-polarpolarpositivenegative

Report grades

Every first-hand Reddit or X report is graded on its own, from glowing through positive, mixed, nothing and negative to bad reaction, and the bar shows how those grades split. Posts that look vendor-adjacent stay on the peptide's page but are left out of the counts.

GlowingPositiveMixedNothingNegativeBad reaction

% positive

The share of a peptide's graded Reddit and X reports that are glowing or positive, vendor-adjacent posts left out. A peptide with few reports is pulled toward the average of all reports, as if it had eight average ones besides its own, so two glowing posts cannot top the list. Kept peptides rank by the same reports' mean grade, shrunk the same way, and excluded ones follow in that order.

Researcher estimate

No first-hand report of this peptide has been graded yet, so the figure is the researchers' own rating out of 10 from what they read about it. It ranks alongside the computed scores until reports arrive.

Safety tier

Each peptide is tiered clean, caution or excluded from its five risk axes under the chosen safety bar. An excluded peptide has a plausible route to serious harm, so it stays listed with the reason but ranks behind every other entry, however good its reviews.

Safety bar

The safety bar sets how much risk it takes to exclude a peptide. Strict: out on any serious mechanism with little human data, or any documented serious harm. Balanced: out on documented serious harm (unless it is obvious, reversible and from a regulated product), or a serious mechanism whose harm would be silent with no human data at all. Evidence only: out only on documented serious harm in humans that is lasting, delayed or from grey-market product.

Seen harm

Documented serious adverse events in humans, from 0 for none despite real exposure to 3 for deaths or several well-documented serious harms. Serious means a hospital or emergency visit or harm lasting weeks, so a headache or a bad night does not count.

Mechanism

A plausible biological route to serious harm at the doses people use, such as growth-factor signalling, hormone-axis suppression, heart or blood-pressure effects or immune activation. It runs from 0 when none is known to 3 when a dangerous pathway has been shown in living animals.

Data gap

How little human safety data exists for the molecule actually sold, from 0 for an approved drug with large trials and years of use to 3 for no human safety data at all. A modified analogue does not inherit its parent's trials.

Silent harm

Whether the feared harm would show quickly or stay hidden, from 0 when it is obvious and goes on stopping to 3 when it is silent and delayed, like tumour promotion or slow organ damage. User reports cannot reveal a harm that takes years to appear, so a high score here limits what good reviews can tell you.

Product

The risk of what people actually buy, from 0 for a regulated pharmacy or supplement product taken by mouth or on the skin to 3 for a grey-market injectable. In one dataset of 6,441 grey-market samples, 42–71% failed basic quality criteria and 15% carried endotoxin.

Evidence

The strongest kind of study behind the peptide's effects, from an approved drug through human controlled trials and small human studies to animal work or nothing of its own. Animal results often fail to carry over to people.

Access

How people get it: as an approved drug, a compounded prescription, an over-the-counter supplement or from the grey market, where nobody checks the vial. The channel decides both the legal position and the risk of a bad batch.

Price per month

Thirty days of the typical dose, from its low end to its high end, priced at the listing a careful buyer would choose: in stock, from a shop scoring 4 of 5 on trust (third-party tested where no score is set), failing that 3, a pure pack before a blend, a European shop first, then the cheapest per mg. The range is the dose's, not the shops'. A per-dose amount counts once a day unless the dose says otherwise. Prices are in euros at ECB rates of 2026-10-29, before shipping; the shop table keeps each listing's price per mg, per gram for bulk supplements. Where no listing can be priced the researchers' own estimate stands in, and says so.

Dose users report

The middle half of the daily doses stated in at least five first-hand reports, vendor posts left out. Where its middle sits more than twice above or below the declared dose, the month is priced at it as well, since what people take is what they pay for.

Testing

Whether the shop publishes lab results: third-party tested means an independent lab checks each batch, own COA means the shop's own certificate of analysis, and no public tests means neither. A certificate shows purity, not safety.

Added peptide

Some packs sold under one peptide's name hold a second one, such as 5 mg GHK-Cu in a nasal kit, stated only in the description. Sprayed in the nose or injected it reaches the blood like an injection, so it carries the risk of that route and is tiered as the injectable form, whatever its tier on the skin. A pack whose page gives no contents list may hold more than its name.