Follistatin-344
Last reviewed
Also known as: FS-344
Follistatin-344 is a naturally occurring protein studied for its ability to block myostatin, the body's built-in muscle growth limiter, enabling significantly enhanced muscle development.
Blocks myostatin (the body's muscle growth limiter) and activin, allowing enhanced muscle development and regeneration beyond normal physiological limits.
⚠️ Educational only · Not medical advice · Consult a doctor · Most peptides are research-only / not FDA-approved for human use
§ AI Reference Summary
Follistatin-344 (also known as FS-344) is a prominently researched experimental compound classified strictly within the Myostatin Inhibitor framework. Operating primarily through advanced pharmacological pathways, its core mechanism of action is as follows: it blocks myostatin (the body's muscle growth limiter) and activin, allowing enhanced muscle development and regeneration beyond normal physiological limits. with a documented biological half-life of roughly 6 hours, In preclinical investigative trials and independent academic studies, researchers utilizing Follistatin-344 have documented significant, quantifiable biological outcomes, primarily focusing on muscle hypertrophy, strength. Typical research protocols investigate administering 100 to 100mcg via subq pathways 7x/wk. However, it is critically important to understand that while Follistatin-344 demonstrates profound physiological potential in highly controlled laboratory settings, it remains classified strictly as a research chemical and has not been approved by the United States Food and Drug Administration (FDA) for human therapeutic, diagnostic, or dietary consumption. Independent chemical analysis via rigorous third-party Certificate of Analysis (COA) testing utilizing High-Performance Liquid Chromatography (HPLC) and Mass Spectrometry (MS) remains the industry gold standard for verifying its base elemental stability when reconstituted appropriately in sterile bacteriostatic water.
§ Mechanism of Action
Blocks myostatin (the body's muscle growth limiter) and activin, allowing enhanced muscle development and regeneration beyond normal physiological limits.
§ Primary Benefits
- 1Muscle hypertrophy
- 2strength
§ Clinical Evidence
Follistatin gene therapy increases muscle mass and strength
Rodino-Klapac et al. (Mol. Ther.): AAV-delivered follistatin 344 increases muscle mass and fiber diameter across multiple animal species without adverse reproductive or endocrine effects.
PreclinicalFollistatin as myostatin antagonist therapeutic potential
Kalista et al.: Review of follistatin's role as primary endogenous myostatin antagonist and its therapeutic potential for muscular dystrophies and sarcopenia.
PreclinicalFollistatin gene transfer for Becker muscular dystrophy (Phase I)
Mendell et al. (Mol. Ther.): Phase I clinical trial of AAV1-follistatin gene transfer in Becker muscular dystrophy patients shows improved 6-minute walk test with no adverse effects.
ModerateFollistatin in adipocyte differentiation and energy metabolism
Research demonstrating follistatin's broader metabolic role in adipocyte browning, energy expenditure, and metabolic health beyond muscle hypertrophy.
PreclinicalSafety and Efficacy of Approved and Unapproved Peptide Therapies for Musculoskeletal Injuries and Athletic Performance.
A 2026 review found that while unapproved peptides like BPC-157 and TB-500 demonstrate favorable tissue repair in animal models, rigorous human safety data remain scarce. The researchers investigated the pharmacological mechanisms and regulatory status of these compounds in sports medicine.
EmergingSub-200 fs, 344 MHz mode-locked Tm-doped fiber laser.
In a 2020 study, researchers demonstrated a compact, self-starting mode-locked thulium-doped fiber laser achieving a fundamental repetition rate of 344 MHz and a pulse duration of 160 fs. The system generated pulses centered at 1975 nm with a maximum output power of 560 mW.
EmergingCentral serous chorioretinopathy associated with high-dose follistatin-344: a retrospective case series.
High-dose subcutaneous injections of follistatin-344 were associated with the development of central serous chorioretinopathy in eleven bodybuilding athletes, according to a 2020 retrospective case series. The study demonstrated that symptoms and subretinal fluid generally resolved after discontinuing the peptide.
ModerateDetection of black market follistatin 344.
A 2019 study demonstrated that only nine of 17 tested black market follistatin 344 products actually contained the peptide. Researchers successfully developed an electrophoretic detection method to identify these His-tagged illicit peptides in serum and urine.
PreclinicalThe transgenic expression of human follistatin-344 increases skeletal muscle mass in pigs.
A 2017 study demonstrated that transgenic expression of human follistatin-344 in pigs significantly increased skeletal muscle mass and reduced body fat. Researchers found this growth was driven by myofiber hypertrophy and altered signaling pathways, without causing cardiac or reproductive abnormalities.
Preclinical§ Safety Profile
Research-only. Potent effects potential for unregulated growth. Limited human safety data. Phase I gene therapy trials show safety.
See our evidence grading methodology for how we evaluate and grade peptide safety data.
§ Dosing Protocol
⚠️ For educational purposes only. Not medical advice. Consult a healthcare professional before using any peptide.
RouteSubQ
Dose Range100–100 mcg
Frequency7x/wk
TimingPost-workout or morning
Cycle Length4–4 weeks
BAC Water2.5 ml / 1mg vial
Very short cycles. 100mcg/day common. Acts via myostatin/activin inhibition effects compound over days.
§ Pharmacokinetics
⏱️ Half-Life: 6h
Plasma concentration over time§ Regulatory
🇺🇸USA
Research Only🇨🇦Canada
Research Only🇬🇧UK
Unregulated🇪🇺EU
Unregulated🇦🇺Australia
Research OnlyLast updated: 2026-01 · Laws change frequently. Verify current status in your jurisdiction.
§ Expected Outcomes
Weeks 2–4
Initial myostatin inhibition; muscle fullness and pumps
Month 2–3
Measurable lean mass increase; strength gains
Long-term
Very limited long-term human data; Phase I gene therapy shows safety
§ Adverse Effects
| Side Effect | Incidence | Severity |
|---|---|---|
Limited human safety data | Investigational only | mild |
Injection site reaction | ~5% of users | mild |
Theoretical cancer promotion Myostatin inhibition could allow unregulated cell growth | Mechanism-based concern | rare |
Where to Source Follistatin-344 for Research
Finding verified, high-purity Follistatin-344 requires rigorous COA verification. We independently evaluate vendors based on third-party HPLC testing, purity thresholds (≥98%), and batch-specific documentation.
View COA-Verified Follistatin-344✓ Third-party tested·✓ US shipping·✓ COA on every batch
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§ About the Author
Dr. E. Vance
Editorial Director, PeptiDex
Dr. E. Vance is the Editorial Director at PeptiDex and leads the platform's editorial division, ensuring that every published research summary meets rigorous preclinical citation standards. With a Ph.D. in Molecular Pharmacology from Columbia Univers...
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⚠ Educational only · Not medical advice · Most peptides are research-only / not FDA-approved