# FGL

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

- Page: https://peprank.xyz/peptides/fgl
- Category: Neuroprotection & repair (Research peptide)
- Also known as: FGLL; NCAM-derived FG-loop peptide
- Routes: Nasal / Injection
- Sequence: EVYVVAENQQGKSKA (NCAM FG-loop peptide; commonly used as a dendrimer (FGLL))
- Safety tier: Strict: Avoid · Balanced: Caution · Evidence only: Caution
- Risk axes (0 none to 3 severe): Seen harm 0, Mechanism 2, Data gap 2, Silent harm 3, Product 2
- Positive: 43% of 1 graded reports glowing or positive, shrunk toward the 49% all-report average by 8 reports' weight
- Rank: #47 of 61 research peptides
- Graded reports: 1 (Nothing 1)
- Evidence: Small human studies — Phase 1 safety/PK only; plus animal
- Access: Grey market
- 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.
- Cost per month: No meaningful figure: the phase-1 doses (25-200 mg per dose) would cost far more than other research peptides at vendor prices.
- Updated: 2026-10-30

**Why Avoid under the strict bar:** Agonist of the mitogenic FGF receptor, with only phase-1 data and no users to learn from.

## What users report

No meaningful user base for cognitive use. Note: 'FLGR-242' discussed on Reddit is an unrelated myostatin-targeting product, not FGL.

**Effects:** none reported in humans

**Downsides:** unknown

**Risks:** 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

**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.

## Risk profile

- **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.
- **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.
- **Data gap 2/3:** One single-dose phase 1 in 24 healthy men; no repeat-dose human data, and development stopped there.
- **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)

## Top reports

- Nothing, neuroprotection: “The HA - FGL isn't working but I stumbled across another supplement that could work, D - Serine.” — [r/neuro](https://www.reddit.com/r/neuro/comments/rp4rx8/could_the_peptide_fgl_reverse_alterations_to_nmda/hqehwl6/)

## Studies

- [2007 phase 1: tolerability and pharmacokinetics of intranasal FGLL in healthy volunteers](https://pubmed.ncbi.nlm.nih.gov/17375985/) (open-label, n=24, 2007): Single 25-200 mg nasal doses were well tolerated (brief nasal burning, runny eyes); plasma levels were detectable for 1-4 hours at the higher doses.
- [Neiiendam et al. 2004: the NCAM-derived FGL peptide is an FGF-receptor agonist](https://pubmed.ncbi.nlm.nih.gov/15525346/) (in-vitro, 2004): FGL activated FGF receptor 1 and induced neurite outgrowth and survival in cultured rat neurons.
- [Cambon et al. 2004: an NCAM mimetic peptide promotes synaptogenesis and memory consolidation](https://pubmed.ncbi.nlm.nih.gov/15115815/) (animal, 2004): FGL injected into the brain right after training gave a long-lasting memory improvement in rats and promoted synapse formation in hippocampal cultures.
- [Klementiev et al. 2007: an NCAM-derived peptide reduces amyloid-beta-induced pathology and memory loss](https://pubmed.ncbi.nlm.nih.gov/17223274/) (animal, 2007): Systemic FGL prevented or reduced amyloid-beta-induced neuron loss, tau phosphorylation, inflammation and memory impairment in rats (authors from the developer, ENKAM).
- [Corbett et al. 2013: amyloid-beta-induced CA1 cell loss alleviated by systemic FGL](https://pubmed.ncbi.nlm.nih.gov/23951173/) (animal, 2013): Systemic FGL prevented social-recognition memory loss and CA1 pyramidal cell loss after amyloid-beta injection in young rats.

## Sources

- [2007 phase 1: tolerability and PK of intranasal FGLL in healthy volunteers](https://pubmed.ncbi.nlm.nih.gov/17375985/)
- [Neiiendam et al. 2004: FGL peptide is an NCAM-derived FGF-receptor agonist](https://pubmed.ncbi.nlm.nih.gov/15525346/)