PepRank

Follistatin-344

44%positive10 reports

Also: FS344 · FST-344 · 'F-344' · follistatin-315 (FS315) · AAV1.FS344 / plasmid follistatin (gene therapy)

ExcludedRecoveryMetabolicInjection

Myostatin/activin-binding protein sold as 1 mg vials; about half of tested vials held no follistatin.

#47 of 61 research peptides · updated
Onset
Unknown: there are no human pharmacokinetic data for injected follistatin protein. Users claim effects within days, which is not plausible for muscle growth.
Lasts
Unknown for the protein (users quote anything from 90 minutes to 12 hours); gene therapy is designed to last months or longer.
Access
Grey market
Cost / month
≈ €180–450
researchers' estimate; no listing to price
10 user reports
Glowing 3Positive 1Nothing 3Negative 2Bad reaction 1

  • r/Biohackers· · 4 upvotesOriginal ↗

    10 pounds of lean muscle in 20 days. Only lost 2 of them. And im a hard gainer as F.

    GlowingRecovery · 100 mcg/day · Injection · 20 days

    also on TRT 150 mg/week and 250 g protein a day, so the gain cannot be attributed

  • r/Biohackers· · 2 upvotesOriginal ↗

    ive started follistatin 344 around a week and a half ago and i honestly have seen huge changes

    GlowingRecovery · Injection · about 10 days

    130 lb woman training 6 days a week; a strength jump this fast is not plausible from muscle growth

  • r/Biohackers· · 2 upvotesOriginal ↗

    I did my Follistatin 344 gene therapy at Roatan with Dr.Terry it’s been 3 months for me now since, but I haven’t noticed any effects yet.

    NothingLongevity · Injection · 3 months since treatment

    follistatin gene therapy on Roatán (Honduras), not the peptide

Strict case
Blocks myostatin and activin signalling (FSH axis, angiogenesis, glucose) with no human safety data for the injected protein; vials often hold other drugs.
Users report
Eleven reports: eight on grey-market vials and three on offshore gene therapy. The four glowing or positive vial reports (10 lb in 20 days, a 40 lb deadlift jump in a week, 'super soldier serum') all come from people also on testosterone, tesamorelin/ipamorelin or a hard training block, or describe gains too fast to be muscle. The others get sore, swollen injection sites lasting days, flu-like symptoms, fatigue and fog, or nothing. Replies in these threads overwhelmingly call it a waste of money. Of three gene-therapy patients (offshore clinics in Mexico and Honduras; one paid $25,000), two noticed nothing and one, who gave no details, called the results impressive. Felt nothing: Of 8 reports on the vials, 1 says it does nothing and 3 describe only injection-site or flu-like reactions; 2 of 3 gene-therapy reports felt nothing..
Best effects
Claimed strength and 'pump' (confounded by steroids, GH secretagogues and training) · muscle growth in animal and gene-therapy studies
Downsides
Swollen, painful injection-site lumps lasting days · flu-like symptoms, fatigue and mental fog · very expensive per mg · no measurable effect for many users
Watch
Product: in an anti-doping lab test only 9 of 17 black-market 'follistatin 344' vials contained follistatin; some held GHRP-2 or mechano growth factor instead (Reichel 2019) · Activin/FSH axis: follistatin neutralises activin, which drives pituitary FSH; mice overexpressing it have reproductive defects · Angiogenic in vivo (rabbit cornea), strongly so together with bFGF: a theoretical route to feeding tumour vessels · Higher circulating follistatin tracks with type 2 diabetes, heart failure and death in a 4,733-person cohort (association, not proof) · A related myostatin/activin trap, ACE-031, was halted in a pediatric trial for nosebleeds and telangiectasias
Evidence
Animal only — animal data for the protein; the only human data are 12 patients given intramuscular AAV1.FS344 gene therapy for muscle disease, which says nothing about injecting the protein
Caveat
FS344 is a roughly 38 kDa protein isoform (the precursor of circulating FS315), not a short peptide; whether a lyophilised research vial holds intact, active protein is unverified, and the anti-doping test found many held none. The gene-therapy results come from muscle-disease patients and a different delivery, and the offshore clinics' own outcome data are unpublished or self-reported.
Typical use
Users: 50-100 mcg/day subq or IM for 10-20 days, some up to 1 mg/day. No human dose has been studied for the protein.
Getting it
Sold as 1 mg 'research' vials of recombinant, mostly E. coli-made protein; never approved. Plasmid follistatin gene therapy is offered at offshore clinics (Próspera and Roatán in Honduras, Mexico) for about $25,000. WADA-prohibited (S4.3); gene doping is banned separately.
Stacked with
Testosterone and other anabolic steroids: Most glowing reports come from people on TRT or a steroid cycle, so the steroid explains the gain. · Tesamorelin / ipamorelin or IGF-1 LR3: Run alongside GH secretagogues or IGF-1 LR3 in 10-20 day 'myostatin' blocks.

User reports 11

  • r/Biohackers· · 4 upvotesOriginal ↗

    10 pounds of lean muscle in 20 days. Only lost 2 of them. And im a hard gainer as F.

    GlowingRecovery · 100 mcg/day · Injection · 20 days

    also on TRT 150 mg/week and 250 g protein a day, so the gain cannot be attributed

  • r/Biohackers· · 2 upvotesOriginal ↗

    ive started follistatin 344 around a week and a half ago and i honestly have seen huge changes

    GlowingRecovery · Injection · about 10 days

    130 lb woman training 6 days a week; a strength jump this fast is not plausible from muscle growth

  • r/Testosterone· · -2 upvotesOriginal ↗

    344 merk ik veel spiergroei en herstel. Heb nooit spierpijn en het is alsof ik op een “super soldier serum” ben zeggen me vrienden.

    GlowingRecovery · Injection

    Dutch-language comment; on 500 mg/week testosterone at the same time; replies say the follistatin is doing nothing

  • r/BodyHackGuide· · 1 upvotesOriginal ↗

    I did 100mcg/day for 10 days. Injected into abdomen w insulin needle. Yes I put on about 5lbs of lean mass over 5 weeks.

    PositiveRecovery · 100 mcg/day for 10 days · Injection · 10-day course

    simultaneously on tesamorelin and ipamorelin with a heavy push-pull-legs block

  • r/Biohackers· · 2 upvotesOriginal ↗

    I did my Follistatin 344 gene therapy at Roatan with Dr.Terry it’s been 3 months for me now since, but I haven’t noticed any effects yet.

    NothingLongevity · Injection · 3 months since treatment

    follistatin gene therapy on Roatán (Honduras), not the peptide

  • r/Biohackers· · 2 upvotesOriginal ↗

    Don't waste your money, all your're gonna get is painful injections. Shit don't work.

    NothingRecovery · Injection

  • r/Biohackers· · 2 upvotesOriginal ↗

    I have to honestly say that I did not get much of anything noticeable out of the follistatin therapy. No enhanced sense of wellbeing or physical changes.

    NothingLongevity · Injection

    plasmid follistatin gene therapy at an offshore clinic (Cabo), not the peptide; had stem-cell treatments at the same visit

  • r/BodyHackGuide· · 2 upvotesOriginal ↗

    Just took my 10th daily dose (1mg) of Follistain 344. I’m getting swollen painful lumps at injection sites. They last several days.

    NegativeRecovery · 1 mg/day · Injection · 10 days

  • r/Biohackers· · 1 upvotesOriginal ↗

    J’ai aussi une inflammation qui apparaît deviens rouge et gonflé pendant plusieurs jours. Je n’ai aucun autre symptôme pas de grippe ou autre

    NegativeRecovery · 50-100 mcg before heavy sessions · Injection

    French-language comment; no flu-like symptoms

  • r/Biohackers· · 1 upvotesOriginal ↗

    Currently using 344: the sore, swollen injection sites are legit and the “flu-like” symptoms are kicking my ass, and the 12-hr half life has proven true. Nobody talks about the fatigue or mental fog.

    Bad reactionRecovery · started at 50 mcg · Injection

  • r/Biohackers· · 2 upvotesOriginal ↗

    I did the therapy and had pretty insane impressive results. Did it via MiniCircle in Honduras

    GlowingLongevity · Injection · vendor-adjacent

    Minicircle plasmid gene therapy in Honduras, not the peptide; no details given and offers to continue by PM

Safety

Tier by safety barStrict ExcludedBalanced ExcludedEvidence only Caution

Seen harmMechanismData gapSilent harmProduct

Seen harm 0/3
No published case reports, regulator warnings or trial SAEs for injected follistatin protein; the 12 muscle-disease patients given AAV1.FS344 gene therapy had no reported adverse effects. Reddit reports are swollen, painful injection sites lasting days, flu-like symptoms and fatigue, which are not serious by the rubric. The zero reflects essentially no documented exposure, not reassurance. Mendell et al. 2015: follistatin gene therapy in Becker muscular dystrophy (no adverse effects) ↗Mendell et al. 2017: follistatin gene therapy in inclusion body myositis ↗r/Biohackers: swollen injection sites, flu-like symptoms, fatigue and fog on FS344 ↗
Mechanism 2/3
Credible pathways from its targets: it neutralises myostatin and activin, which suppresses pituitary FSH (hormone axis), and recombinant follistatin is angiogenic in the rabbit cornea, strongly so with bFGF (vessel growth in animals). A related ligand trap, ACE-031, caused nosebleeds and telangiectasias that stopped its pediatric trial, and higher circulating follistatin tracks with diabetes and mortality in a cohort study. Transgenic overexpression causes reproductive defects in mice, but that is lifelong genetic exposure rather than use exposure, so this stays at 2, not 3. Kozian et al. 1997: follistatin induces angiogenesis ↗Guo et al. 1998: follistatin overexpression causes reproductive defects in mice ↗Campbell et al. 2017: ACE-031 trial stopped for epistaxis and telangiectasias ↗Malmö cohort 2023: elevated circulating follistatin, mortality and cardiometabolic disease ↗
Data gap 3/3
No human safety data for the product sold, recombinant (mostly E. coli-made, His-tagged) follistatin injected subcutaneously. The only human exposure is intramuscular AAV1 gene therapy in 12 patients with muscle disease and unpublished offshore plasmid treatments, which differ in delivery, dose and duration and do not bridge to the vials. Mendell et al. 2015: AAV1.FS344 in six Becker patients ↗WADA: detection of follistatin doping (black-market products are E. coli-expressed) ↗
Silent harm 3/3
The angiogenic pathway points at theoretical support for tumour vessels, which is silent and delayed (3 under the rubric). Fertility and glucose effects would build up but show on hormone or glucose tests (a 2); injection-site and flu-like reactions are immediate. Kozian et al. 1997: follistatin is angiogenic in vivo ↗
Product 3/3
Grey-market injectable vials. An anti-doping laboratory found follistatin in only 9 of 17 black-market 'follistatin 344' products; the rest held other growth-promoting peptides such as MGF or GHRP-2, and all genuine samples were His-tagged recombinant protein with heavy oligomerisation. Users describe swollen, painful injection sites lasting days. Reichel et al. 2019: detection of black-market follistatin 344 ↗r/BodyHackGuide: swollen painful lumps after 10 daily 1 mg doses ↗
Never if
Pregnancy, breastfeeding or trying to conceive (follistatin suppresses FSH; overexpressing mice have reproductive defects) · Active or past cancer (angiogenic in vivo) · Diabetes or prediabetes · Under 18

Studies 8

Sources 5

More in Hormones & libido all 12 →

  1. 1GHRP-6 Excluded Injection≈ €13–81 / month59%positive14 reportsFirst-generation GHRP used as an appetite drug for bulking; strong hunger, cortisol, glucose, GH axis.GH/IGF-1 axis elevation plus cortisol rise and reduced insulin sensitivity (FDA), with only single-dose human safety data.
  2. 2Kisspeptin YNWNSFGLRF (10 residues) Excluded Nasal / Injection≈ €4.1–12 / month52%positive30 reportsTop-of-axis GnRH stimulator for libido/testosterone; chronic use can crash the axis.Directly manipulates the HPG axis; continuous or long-acting exposure suppresses it.
  3. 3Hexarelin Excluded Injection≈ €27–110 / month45%positive5 reportsMost potent GHRP; fast desensitisation, acute cortisol/prolactin rise and direct CD36 heart effects.GH/IGF-1 axis elevation, acute cortisol and prolactin release, and GH-independent actions on heart and coronary vessels via CD36.
  4. 4IGF-1 DES Excluded Injection≈ €22–180 / month49%positive4 reportsShort-acting, truncated IGF-1 injected into the trained muscle; very potent at dropping blood sugar.An IGF-1 receptor agonist about ten times as potent as IGF-1 in cells and the most hypoglycaemic of the IGF-1 variants in primates, with no human data, the same tumour-promotion concern as LR3, and grey-market vials that are rarely tested.
  5. 5MK-677 Excluded Oral≈ €18–54 / month48%positive29 reportsOral GH secretagogue (not a peptide); hunger, bloat, insulin resistance, CHF signal.GH/IGF-1 elevation, insulin resistance and a CHF safety signal in an RCT.
  6. 6IGF-1 LR3 Excluded Injection≈ €36–140 / month40%positive24 reportsLong-acting IGF-1 analogue (a cell-culture reagent) for muscle; hypoglycaemia, tumour-growth signal.A potent, long-acting IGF-1 receptor agonist with no human data at all: it accelerated tumour growth in mice, the same receptor causes hypoglycaemic seizures and carries a malignancy warning on the approved IGF-1 drug, and every vial is grey-market.
  7. 7Sermorelin YADAIFTNSYRKVLGQLSARKLLQDIMSR (29 residues) Excluded Sublingual / Injection≈ €38–94 / month46%positive29 reportsShort GHRH analogue; cheap, gentle, sleep-focused, still GH/IGF-1 axis.GH/IGF-1 axis elevation, though the mildest of the class.
  8. 8PT-141 DHFRWK (6 residues) Excluded Nasal / Injection≈ €24–170 / month39%positive30 reportsFDA-approved melanocortin libido drug; works strongly for many, raises blood pressure.Cardiovascular effects (BP spikes; contraindicated in CVD) and melanocortin pigmentation effects.
  9. 9GHRP-2 Excluded Injection / Nasal / IV≈ €18–45 / month39%positive7 reportsJapan-approved GH diagnostic sold as a vial; hunger, cortisol and prolactin spikes, GH axis.GH/IGF-1 axis elevation with cortisol and prolactin spikes; FDA notes raised insulin needs and deaths in critically ill subjects.
  10. 10Ipamorelin Excluded Injection≈ €11–100 / month42%positive51 reportsSelective ghrelin-receptor GH secretagogue; sleep and recovery, GH axis plus reactions.GH/IGF-1 axis elevation plus repeated anaphylaxis reports, including a coroner-attributed death.
  11. 11CJC-1295 YADAIFTQSYRKVLAQLSARKLLQDILSR (29 residues) Excluded Injection≈ €14–27 / month38%positive29 reportsLong-acting GHRH analogue stacked with ipamorelin; GH axis, vasodilatory reactions.GH/IGF-1 axis elevation plus FDA-noted tachycardia/vasodilatory reactions and anaphylaxis.

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.