Bones & muscles Myostatin-inhibiting peptide
Follistatin-344
Regulatory status
Status at a glance
503A compounding status
Not nominated
We found no pending nomination for the 503A bulks list. Unless the substance has another legal pathway (for example, a USP monograph or use in an FDA-approved drug), 503A pharmacies generally may not compound with it.
- FDA approval
- Not FDA-approved for any use
- 503B outsourcing
- Not determined
- Anti-doping (WADA)
- On the WADA Prohibited List
- DEA schedule
- Not a controlled substance
About peptide status
Most peptides discussed here are not FDA-approved for any use, and products labeled “research use only” are not for human use. Removal from Category 2 does not authorize compounding. PCAC votes are non-binding recommendations; FDA and HHS make the final decisions.
This is not medical or legal advice, and we do not publish dosing, sourcing or reconstitution information. Talk with a licensed clinician before using any peptide.
If you think you are having a medical emergency, call 911.
Key takeaway
Follistatin-344 is a form of the natural protein follistatin that blocks myostatin, a brake on muscle growth, sold as a "research chemical" in the performance market for muscle gain. The strongest human data come from gene therapy, not the injectable peptide. In a small 2017 trial, six patients with sporadic inclusion body myositis gained a median 56.0 m per year on the 6-minute walk test after follistatin gene therapy, versus a 25.8 m decline in eight matched untreated controls (p = 0.01). It is not FDA-approved and is banned in sport.
At a glance
- FDA status
- Non-FDA-approved peptide sold as a research chemical/performance drug
- What it is
- Myostatin-binding protein, marketed to remove a natural brake on muscle growth
- Research
- Human data come only from small gene-therapy disease trials, not the injectable peptide
- Sport
- Prohibited by WADA at all times
- Evidence strength
- Low research
Summary
Follistatin-344 is a myostatin-binding protein sold for muscle gain. See how it works, why it is not FDA-approved, and what human research exists.
What is follistatin-344?
Follistatin is a natural protein that binds and neutralizes myostatin and related factors. Follistatin-344 (FS344) refers to a specific 344-amino acid form used in research and gene-therapy work. In the performance market, an injectable "follistatin peptide" is sold for muscle growth, though it is a different, uncharacterized product from the gene-therapy material. It is not an approved medicine.
How does it work?
Myostatin normally limits how much muscle the body builds. By binding and neutralizing myostatin, follistatin is proposed to release that brake and allow greater muscle growth. This pathway is well supported in animal models, where disrupting myostatin signaling produces pronounced muscle growth. This describes the proposed mechanism, which comes from animal work, separate from proven outcomes in people using the injectable peptide.
Is it FDA-approved?
Safety note
Status: Non-FDA-approved peptide sold as a research chemical/performance drug
Category: Wellness and performance · Primary body area: Bones & muscles
No. Follistatin-344 is not approved by the FDA as a drug. Its status by form and setting:
- Injectable peptide: a research chemical and performance-enhancing drug with no recognized compounding status
- Gene therapy: remains investigational
- Sport: myostatin-binding proteins including follistatin are prohibited at all times under the WADA list
What does the research show?
Editor’s note
Evidence strength: Low research (2 human · 0 animal/cell studies)
The myostatin-inhibition rationale is strong in animals, but there is no human efficacy evidence for the injectable peptide; the only human data come from small gene-therapy disease trials that do not transfer to the wellness use.
The human evidence belongs to gene therapy, not the peptide. According to PubMed, a small Phase 1/2a trial used a gene therapy delivering the follistatin (FS344) gene in six patients with Becker muscular dystrophy, reporting some walking improvements and muscle changes; follow-up reported ambulation data. This is a disease population and a gene-therapy delivery, not the injectable follistatin peptide sold for wellness, and it does not establish efficacy or safety of that peptide in healthy people. There are no controlled human trials of the injectable peptide.
Two small studies of this gene therapy report walking results:
| Study | Patients | Design | Result |
|---|---|---|---|
| Phase 1/2a trial in Becker muscular dystrophy | 6 treated | No placebo group | 4 of the 6 walked farther on the 6-minute walk test, by 29 m to 125 m; muscle biopsies showed less fibrosis |
| Study in sporadic inclusion body myositis, an inflammatory muscle disease, published in 2017 | 6 treated, versus 8 matched, untreated controls | Same gene therapy alongside an exercise regimen; controls not randomized | Treated patients gained a median 56.0 m per year on the 6-minute walk test, versus a 25.8 m decline in controls (p = 0.01), with individual changes of 5 to 153 m |
The 2017 sample was tiny and the controls were not randomized, so that result is hypothesis-generating.
Sources: a Phase 1/2a follistatin gene-therapy trial (Mendell et al., Molecular Therapy, 2014, DOI: 10.1038/mt.2014.200) and its follow-up (Journal of Neuromuscular Diseases, 2015, DOI: 10.3233/jnd-150083), indexed on PubMed; and the WADA Prohibited List. This document is educational, is not medical advice or a health claim, and is not an offer to sell any product.
Registered human trials
2 registered human trials on ClinicalTrials.gov that we reviewed
Sources
- [1]
- [2]
- [3]
- [4]
- PMID 25322757
- [5]
Compare every peptide’s status in the peptide regulatory status database
More for Bones & muscles
View all bones & muscles peptides →- FDA-approved Bones & muscles
Abaloparatide
Abaloparatide is a synthetic 34-amino acid analog of parathyroid hormone-related protein (PTHrP) that activates the PTH1 receptor to stimulate new bone formation. FDA-approved in 2017 as Tymlos, it is a daily injection for postmenopausal women and men with osteoporosis at high fracture risk, and it is capped at two years of use. In the pivotal ACTIVE trial, it cut the risk of new spine fractures by about 86% versus placebo.
- FDA-approved Bones & muscles
Calcitonin-Salmon
Miacalcin (injection), nasal spray sold as a generic
Calcitonin-salmon is an FDA-approved synthetic version of a natural hormone that slows bone breakdown, used mainly for postmenopausal osteoporosis, Paget's disease of bone, and high blood calcium (hypercalcemia). It comes as an injection, sold as Miacalcin, and as a nasal spray sold as a generic. A modest effect on fractures and a small possible cancer risk with long-term use make it a second-line option today.
- Not FDA-approved Bones & muscles
Cjc-1295
CJC-1295 is a synthetic long-acting analog of growth-hormone-releasing hormone (GHRH). In two placebo-controlled trials of healthy adults aged 21 to 61 (Teichman, 2006), a single injection raised mean growth hormone 2- to 10-fold for 6 days or more. Mean IGF-1 rose 1.5- to 3-fold, but no controlled human trial shows benefit for muscle, fat loss, recovery, or anti-aging. CJC-1295 is not FDA-approved, it is not eligible for routine pharmacy compounding, and it is banned in sport.
- FDA-approved Bones & muscles
Etelcalcetide
Etelcalcetide (sold as Parsabiv) is a peptide that activates the calcium-sensing receptor to lower parathyroid hormone, used for secondary hyperparathyroidism in people on dialysis for kidney disease. Unlike parathyroid hormone replacement, it suppresses an overactive parathyroid signal, and it is given intravenously at the end of each dialysis session. It has been FDA-approved in the U.S. since 2017.
- Not FDA-approved Bones & muscles
Ghrp-2
Pralmorelin
GHRP-2 (pralmorelin) is a synthetic ghrelin-mimic peptide that prompts the pituitary to release growth hormone, sold in the wellness market for muscle, recovery, and appetite. Its only genuine validated use is as a diagnostic test of growth hormone capacity (approved in Japan), not as a treatment, and there are no controlled trials supporting the marketed wellness benefits. As of 2026 it is not FDA-approved and is banned in sport.
- Not FDA-approved Bones & muscles
Ghrp-6
GHRP-6 is one of the original synthetic ghrelin-mimic peptides, sold in the wellness market to raise the body's own growth hormone and stimulate appetite. Human data are limited to short studies of growth hormone release, with no controlled trials proving the marketed muscle, recovery, or anti-aging benefits. As of 2026 it is not FDA-approved and is banned in sport.