# Dihexa

A lab-made compound from one university group, promoted online as a powerful memory enhancer on the strength of rat studies. FDA has found no record of it ever being given to people in a study.

Also called: PNB-0408
Source page: https://peplogue.com/peptides/dihexa/
Reviewed: 2026-10-12. Not medical advice.

## How it works

- Where it acts: It binds HGF, a growth factor, and boosts its signalling through the MET receptor.
- What it changes: In rats, more connections between nerve cells and better memory.
- What people notice: No human studies. MET signalling also drives some cancers, a theoretical risk.

## What the evidence shows

- **Memory and learning**: Lab only. Rat and cell studies from a single lab. Four related papers from that lab carry journal notices about possible image manipulation.

## Side effects and risks

- unknown: No human safety data of any kind.
- unknown: Reported to act through a growth pathway (HGF and c-Met) that is also active in many cancers.

Who should avoid it: Everyone.

## How it has been given in studies

No human dose exists.

## Legal status

- United States: undefined
- European Union: undefined
- Spain: undefined. Research peptide. No authorised medicine in Spain that we found (not individually checked in CIMA). Not lawful to sell to the public.
- Germany: undefined. Not approved in Germany. Selling it as a medicine without approval is a crime (AMG § 21, § 96); sold online only as 'research' products.
- France: undefined. No French authorisation found. Not named by ANSM, but its Jul 2026 alert says peptides bought outside the official circuit are illegal.
- Italy: undefined. No Italian authorisation found. Not lawful to sell to the public as a medicine. Research-grade vials online are unverified products.
- Netherlands: undefined. No Dutch marketing authorisation found. Selling it as a medicine without one is illegal per IGJ, even if labelled 'research use'.
- United Kingdom: undefined
- Canada: undefined
- Australia: undefined

## Questions people ask

**Does Dihexa improve memory?**

Only rat and cell studies from a single lab support it, and four related papers from that lab carry journal notices about possible image manipulation. There are no human studies.

**Is Dihexa safe?**

There are no human safety data of any kind. It is reported to act through a growth pathway (HGF and c-Met) that is also active in many cancers, a theoretical risk.

**What is FDA doing about Dihexa?**

FDA advisers are due to review it for compounding by February 2027. FDA has found no record of it ever being given to people in a study.

## Sources

- FDA: bulk substances that may present significant safety risks: https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks
- Retraction Watch: four papers earn expressions of concern (Sep 2021): https://retractionwatch.com/2021/09/24/four-papers-by-athira-ceo-earn-expressions-of-concern/
- Retraction Watch: settlement over data-falsification allegations (Jan 2025): https://retractionwatch.com/2025/01/07/biotech-company-athira-settlement-data-falsification-allegations/