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№ 038

Follistatin 344

A compound aimed at unlocking muscle growth by releasing the body's natural brake on it. A myostatin antagonist that binds and neutralizes myostatin, the negative regulator of muscle growth. Theoretical muscle-growth signal, limited human data.

GH-axis
Evidence: Anecdotal

Follistatin 344: A compound aimed at unlocking muscle growth by releasing the body's natural brake on it. A myostatin antagonist that binds and neutralizes myostatin, the negative regulator of muscle growth. Theoretical muscle-growth signal, limited human data. Follistatin 344 blocks myostatin, the protein that puts a ceiling on how much muscle you can build.

FDA ⓘ
Not approved
WADA
Banned
Typical dose
100-300 mcg sub-q daily for 10-30 days
Half-life ⓘ
~hours (poorly characterized)
Route ⓘ
Subcutaneous
Schedule
Daily
In plain English

Follistatin 344 blocks myostatin, the protein that puts a ceiling on how much muscle you can build. Theoretically removing the brake means more muscle growth. Real human data is very limited. Treat as experimental, run short cycles only.

Status & legalityWhat do these mean? →
Natty? ⓘ
Not natty

Myostatin antagonism is universally banned in tested sport.

FDA ⓘ
Not approved

Not FDA approved.

Compounding ⓘ
Not classified

Not formally categorized in the FDA bulks lists.

WADA ⓘ
Banned (S4)

S4 Hormone and Metabolic Modulators, myostatin inhibitors are explicitly listed.

Prescribed ⓘ

Not prescribed in conventional medicine.

Who it's for

  • →Bodybuilders / lifters experimenting with muscle-growth pathways
  • →Researchers studying myostatin biology

What to expect

  1. Week 1

    Anecdotal pumps and fullness reports.

  2. Week 4

    Subjective effects peak around here for responders. Cycle endpoint, stop.

  3. Week 8

    Off-cycle. No long-cycle data exists.

Looking at Follistatin 344? Your next 3 steps

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How it works (mechanism)

Glycoprotein that binds and neutralizes myostatin. Different mechanism from ACE-031, direct ligand-binding rather than receptor-decoy. Theoretically permits increased muscle growth by removing the negative regulator.

Dosing protocol

Members only

Stacks well with

Members only

Side effects

01Limited human safety data
02Theoretical: cardiac and tendon issues with chronic strong myostatin suppression
03Injection-site irritation

When NOT to use

  • ⚠Anyone risk-averse to limited human data
  • ⚠Pregnancy / nursing
  • ⚠Active malignancy

Common mistakes

  • • Running it longer than 30 days without safety data
  • • Treating it as steroid-equivalent (it isn't)
  • • Stacking with too many other compounds and crediting Follistatin for everything

What it actually is

Follistatin 344 is a version of a naturally occurring protein that binds and neutralises myostatin, the signal that limits how much muscle your body will build. The idea is to release the brake rather than press the accelerator. It has essentially no human evidence: five indexed papers, of which two are about detecting it on the black market and one is a case series of eye damage in people who used it.

Myostatin is a member of the TGF-beta family that continuously signals muscle to stop growing. Animals and the rare humans with a broken myostatin gene are dramatically more muscular. Follistatin binds myostatin and prevents that signal reaching its receptor, so in principle muscle grows past its normal ceiling. The catch is that follistatin does not bind myostatin alone — it neutralises several related TGF-beta family ligands that do jobs elsewhere in the body, which is where the unexpected harms come from.

Forms, and which is which

Lyophilised powder, subcutaneousHow all use happens

Buyer reconstitutes. A large protein sold as a research chemical, where identity is impossible to verify and correct folding matters.

Verdict: The only form, and the hardest kind of molecule to verify.

Gene therapy follistatinThe legitimate research context

Studied in muscular dystrophy trials as a gene therapy, a completely different proposition from injecting a protein.

Verdict: Real research, unrelated to what is sold.

ACE-031The other myostatin approach

A decoy receptor that traps myostatin. Its clinical programme was halted over vascular safety signals.

Verdict: Same target, and its trials were stopped for cause.

Oral 'follistatin boosters'Nothing

Supplements claiming to raise follistatin, usually egg-derived. No mechanism supports a meaningful effect.

Verdict: Unrelated to the injectable claim.

What it is claimed to do, graded

Builds muscle in humansNone shown

Zero human trials. The evidence index returns five papers total for this compound and none of them is an efficacy study.

Neutralises myostatinLimited

The biochemistry is real and well established for follistatin as a protein. Whether an injected research-chemical preparation does it in a person is untested.

Is safe for short cyclesNone shown

A 2020 retrospective case series reported central serous chorioretinopathy — fluid under the retina, causing vision distortion — in people using high-dose follistatin-344. That is a documented harm in exactly this population, not a theoretical one.

Effects persist after stoppingNone shown

Widely claimed and untested.

Grades describe how much human evidence exists for that specific claim, not whether it will work for you or whether it is safe.

Pros and cons

Pros
  • • The myostatin biology is genuine and one of the better-understood limits on muscle growth
  • • Short protocols limit total exposure
  • • The mechanism is different from anything hormonal, so it does not carry the endocrine side effects
Cons
  • • Zero human trials — grade F on the site's own ladder
  • • A documented eye harm in real users: central serous chorioretinopathy at high doses
  • • Follistatin neutralises several TGF-beta ligands, not myostatin alone, so off-target effects are expected rather than surprising
  • • The other drug aimed at this target had its trials halted over vascular safety
  • • A large protein sold as a research chemical is the hardest category to verify
  • • Banned in sport

When to stop

  • • Any change in vision — blurring, a dark or distorted patch in central vision. This is the documented harm, take it seriously and get seen
  • • Thirty days, on any protocol — there is no safety data supporting longer
  • • Tendon or joint pain as strength climbs
  • • Any new cancer diagnosis

Interactions

ACE-031 or other myostatin inhibitorsAvoid

Same pathway, compounded off-target suppression, and the other agent's trials were halted for safety.

Active or suspected cancerAvoid

TGF-beta signalling is central to tumour biology in both directions. Broad suppression in a body with a tumour is unstudied.

Anabolic steroidsCaution

Commonly stacked. It makes any effect unattributable and compounds tendon loading against a rapidly growing muscle.

Heavy training loadsCaution

Muscle can gain force capacity faster than tendon adapts, which is a plausible injury mechanism and a recognised theoretical concern with strong myostatin suppression.

Nothing well characterisedCaution

There is no human interaction literature for this compound.

Is this for you?

Probably worth reading further if
  • • Realistically nobody on the current evidence, given a documented eye harm and no efficacy data
Skip it if
  • • You value your vision — the reported harm is retinal and occurred in users at high doses
  • • You have active cancer
  • • You are pregnant or nursing
  • • You are drug-tested in sport

The one number

5 indexed papers total, two of them about detecting black-market product and one a case series of retinal harm
Pepdex evidence index, PubMed; Int Ophthalmol 2020 (PMID 32671599)

Sources for the claims above

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AI Coach, live sample
Member answer
is 250mcg of bpc enough for a knee injury?
For a knee, is the standard working dose and a solid place to start. The trick with BPC is consistency, give it weeks, not days. , run it , and don't drop below , results tend to fall off under that line. If nothing's moved by week 3, that's when earns its place.
how much bac water for a 10mg reta vial?
is the standard play for a 10 mg reta vial. That gives you , clean unit math across the whole titration: on a 100-unit insulin syringe. Run instead if you want fewer, more concentrated shots. Most people titrate up over , and that mix keeps the numbers cleanest.
what should i track on bloodwork for tirzepatide?
Lipid panel, ALT/AST (liver enzymes), and an A1C, baseline before you start then every 3 months. If you've got metabolic-syndrome history, add fasting glucose and insulin so you can actually watch insulin sensitivity improve. You don't need a big hormone panel for a GLP-1.

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Frequently asked

What is Follistatin 344?+
Follistatin 344 blocks myostatin, the protein that puts a ceiling on how much muscle you can build. Theoretically removing the brake means more muscle growth. Real human data is very limited. Treat as experimental, run short cycles only.
Is Follistatin 344 FDA approved?+
Not FDA approved.
Is Follistatin 344 legal?+
Follistatin 344 is not FDA-approved, so there is no approved prescription version. Most supply is sold as "research only" by peptide vendors. A compounding pharmacy may only use substances the FDA permits for compounding, and many research peptides are not permitted — do not assume a compounded prescription is available. Possession is generally not criminalized but distribution without authorization may be. Verify local laws.
Is Follistatin 344 banned by WADA?+
Follistatin 344 is on the WADA prohibited list under Banned (S4). S4 Hormone and Metabolic Modulators, myostatin inhibitors are explicitly listed.
Are you still natty after taking Follistatin 344?+
No. Myostatin antagonism is universally banned in tested sport.
Do doctors prescribe Follistatin 344?+
Not prescribed in conventional medicine.
What's the typical dose of Follistatin 344?+
Dosing depends on your goal, experience, and tolerance. The full Follistatin 344 protocol (dose, frequency, and how to titrate) is in the members section on the entry page.
What are the side effects of Follistatin 344?+
Common side effects include: Limited human safety data; Theoretical: cardiac and tendon issues with chronic strong myostatin suppression; Injection-site irritation. Less common effects and full safety details are on the entry page.
How long until Follistatin 344 starts working?+
Anecdotal pumps and fullness reports.
What can you stack with Follistatin 344?+
Follistatin 344 is commonly combined with complementary compounds. The full stacking protocol (what to pair, dosing, and timing) is in the members section on the entry page.
Where do people get Follistatin 344?+
Pepdex does not sell, ship, or recommend suppliers. Follistatin 344 is not FDA-approved; prescription versions require licensed clinical care, and "research only" markets carry real legal and quality risks. /coa explains how to verify a Certificate of Analysis and /guides/scam-vendor-spotting covers the red flags.

Common questions about Follistatin 344

Tracked alongside Follistatin 344

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MK-677 →
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Creatine →
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Glycine →
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Melatonin →
same reason — the sleep window is the GH window

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