Peptides / Recovery and repair
Natural peptide · 344 amino acids
Follistatin-344
Not approvedBanned in sport
Follistatin-344 is the precursor form of follistatin, a protein that blocks myostatin and activin, which limit muscle growth. No approval as a drug was found, it is banned in sport, and it has very few study results. PepBank shows 4 results on follistatin-344 from 1 study in people. The strongest evidence is a case report or series. Data as of 2026-10-30.
Also known as FS344, FST344, Follistatin 344
First 40 of 344 amino acids2 changed amino acids
Evidence level: Some studies in people4 of 4 results come from studies in people.
Results in people
4
100% of 4 results
Results in animals
0
0% of 4 results
Results in lab cells
0
0% of 4 results
From computer models
0
0% of 4 results
Overview
Follistatin-344 at a glance
| What it is | Natural peptide, 344 amino acids |
|---|---|
| Approval | Not approved for any use |
| In sport | Banned in sport (WADA S4.3) |
| Studies | 1 study with results. It gave follistatin-344, with 4 results. 4 in people |
| Best study in people | Case report or series with 11 people (2020) |
| Clinical trials | None registered |
| Community use | Community muscle growth use |
The science
What is follistatin-344?
344-residue follistatin precursor associated with activin and myostatin inhibition.
344
Amino acids in one chain
Follistatin-344 structure and chemistry
The key facts about the molecule. Long codes are in the closed section below.
Sequence, 344 amino acidsFrom the first amino acid to the last
M1V+RA+R5HQPGG10LCLLL15LLLCQ20FM−E−D+R25SAQAG30NCWL+R35QA+KNG40+RCQVL45Y+KT−EL50S+K−E−EC55CSTG+R60LSTSW65T−E−E−DV70N−DNTL75F+KWMI80FNGGA85PNCIP90C+K−ETC95−ENV−DC100GPG+K+K105C+RMN+K110+KN+KP+R115CVCAP120−DCSNI125TW+KGP130VCGL−D135G+KTY+R140N−ECAL145L+KA+RC150+K−EQP−E155L−EVQY160QG+RC+K165+KTC+R−D170VFCPG175SSTCV180V−DQTN185NAYCV190TCN+RI195CP−EPA200SS−EQY205LCGN−D210GVTYS215SACHL220+R+KATC225LLG+RS230IGLAY235−EG+KCI240+KA+KSC245−E−DIQC250TGG+K+K255CLW−DF260+KVG+RG265+RCSLC270−D−ELCP275−DS+KS−D280−EPVCA285S−DNAT290YAS−EC295AM+K−EA300ACSSG305VLL−EV310+KHSGS315CNSIS320−E−DT−E−E325−E−E−E−D−E330−DQ−DYS335FPISS340IL−EW
Darker means more water-repelling+ and − show charge in the bodyOutlined: changed amino acid
Structure
Follistatin-344 is a natural peptide of 344 amino acids, with no ring, 18 disulfide bonds, 2 changed amino acids.
Target
Activin A (gene INHBA): antagonistEvidence: known
Development
Highest phase: no known clinical development.
Identifiers
UniProt P19883
The evidence
What follistatin-344 studies show
Results grouped by what the studies measured. Each card shows where its results come from.
Some studies in people4 of 4 results come from studies in people.
All 1 study in people
Key follistatin-344 studies
Studies in people come first, then studies in animals and in the lab.
- PeopleCentral serous chorioretinopathy associated with high-dose follistatin-344: a retrospective case series4 resultsDağ et al. 2020 · International ophthalmology · 11 people · cited by 2
Follistatin-344 clinical trials
ClinicalTrials.gov lists no trial of follistatin-344. A trial under another name may exist.
Status and safety
Is follistatin-344 approved?
FDA
United States
Status unknownStatus unknown.
EMA
European Union
Not approvedNo approved medicine contains it.
WADA
Sport
BannedOn the 2026 Prohibited List, section S4.3.
No. Not approved for any use. The sources we use show no clinical development. They show no approval at the EMA or elsewhere (as of 13 Oct 2026). Banned in sport (WADA S4.3).
Laws and labels change, so check the regulator for the current status.
Follistatin-344 side effects and safety
PepBank has 4 safety results from studies of follistatin-344. 4 of them come from studies in people.
Safety results from studies (4)
- In bodybuilding athletes, follistatin‑344 injections preceded CSCR in 11 patients, affecting one eye in ten and both eyes in one. (International ophthalmology, 2020)
- In eight patients with one follistatin‑344 injection, fluid under the retina disappeared after an average of 2.3 months. (International ophthalmology, 2020)
- In eight patients with one follistatin‑344 injection, CSCR symptoms decreased. (International ophthalmology, 2020)
- In three patients with repeated follistatin‑344 injections, CSCR recurred. (International ophthalmology, 2020)
Doses studied (1 shown)
The doses that these studies used. They are not recommendations.
| Dose as reported | Class | Species | Route | Duration | Design | Source |
|---|---|---|---|---|---|---|
| 1 mg | Human | human | subcutaneous | Not reported | Reports of single patients · n = 11 | Dağ 2020 |
From the community
How people use it
What people report online. It comes from forums and guides, not from studies.
Community-reported. Not tested in trials.
A secondary wiki reports this community protocol. This check verifies its quoted wording. It does not verify actual use, safety or efficacy.
Reported routines and cautions
What people use it for
- Community muscle growth useS1
Reported regimens
| Context | Route | Amount | How often | How long | Agreement | Sources |
|---|---|---|---|---|---|---|
| Community muscle growth use | Subcutaneous | 100 mcg per dose | Once daily | 10-20 days per cycle | One secondary wiki source. No independent primary report was checked. | S1 |
Community sources
- S1Follistatin community protocols (opens in a new tab)www.peptideprotocolwiki.com
Gaps
One secondary wiki source supports the reported protocol. Actual use, financial relationships, retail isoform identity, processing and purity remain unresolved. No official manufacturer label regimen was identified. Mature FST315, mature FST288, gene transfer and oral supplements are separate products or interventions.
Questions and more
Ask a question about follistatin-344
The answer links to every study it uses.
Sources
- Database: PepBank data for follistatin-344 (data version 308560)
- Regulator: FDA status record
- Regulator: EMA status record
- Regulator: WADA status record
- Community: community sources (forums and guides), as summarized in the PepBank community file
AI wrote and checked these results. AI can make mistakes, so check important results against the source.
PepBank is a research reference. Talk to a doctor before you use any peptide.
Ask your AI about follistatin-344
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