Follistatin-344 is a potent natural antagonist of myostatin, the body's primary brake on skeletal muscle growth. It has demonstrated remarkable lean mass effects in every animal model tested, from mice to nonhuman primates, and is the only follistatin isoform with human clinical trial data (gene therapy for Becker muscular dystrophy). Not approved for human use. This is not medical advice.
Research-context information only. Follistatin-344 is a research peptide. Protocols, doses, and reactions reported below come from published research and self-reported community sources. This article reports what has been documented, not what should be done. Consult a licensed physician for personal medical decisions.
Parameter Community-Reported Protocol Dose 50 mcg Route Intramuscular injection (IM) Timing 30 minutes pre-workout Frequency Training days only Cycle 8 weeks on, 8 weeks off Vial size 1 mg Reconstitution 2 mL bacteriostatic water → 500 mcg/mL Draw amount 10 units on insulin syringe Storage Lyophilized: -20°C long-term / 2-8°C short-term. Reconstituted: 2-8°C, use within 14-21 days
Community protocols describe 50 mcg IM injection 30 minutes before training, on training days only, for an 8-week active phase.
For the full Follistatin-344 peptide profile, see our follistatin peptide page. For the complete mechanism, see our follistatin benefits guide.
Cycling: 8 Weeks On, 8 Weeks Off
Community protocols describe 50 mcg intramuscularly 30 minutes before training, on training days only, with rest days as off days. This targets myostatin inhibition around resistance training sessions when it matters most.
The 8-week off period allows the body's myostatin/follistatin axis to re-equilibrate and provides a safety window to monitor for emerging side effects.
IM injection sites: Deltoid (most common for small-volume IM), vastus lateralis (outer thigh), or gluteus medius (upper outer glute).
Routes of Administration
Intramuscular injection (standard): IM is the primary route for follistatin-344. The training-day-only timing targets the muscle-building window directly. Trial protocols for IM injections at this volume typically describe 29-31 gauge insulin syringes.
Note on pharmacokinetics: Community peptide doses are extrapolated from gene-therapy studies that used viral vector delivery (sustained local expression over weeks). Direct injection of recombinant follistatin has a much shorter half-life (estimated hours), so the pharmacokinetics are fundamentally different. This is the major caveat underlying all community dosing.
Reconstitution Quick Reference
Vial Size BAC Water Concentration 50 mcg Dose 1 mg 2 mL 500 mcg/mL 10 units
Math: 1,000 mcg / 2 mL = 500 mcg/mL. For 50 mcg: 50 / 500 = 0.1 mL = 10 units. One vial lasts 20 doses.
Follistatin-344 is a fragile protein. Community protocols describe swirling gently rather than shaking; it may take 2-5 minutes to dissolve completely, and the solution should be clear. Community storage protocols describe immediate refrigeration; freezing reconstituted solution is described as damaging the protein. Use within 14-21 days. Community guidance describes discarding solution that appears cloudy or contains visible particles.
For step-by-step instructions, see the Reconstitution Calculator.
Affiliate disclosure: vendor links in this article are affiliate links — The Peptide Catalog may earn a commission if you buy through them, at no additional cost to you.
Where These Numbers Come From
Follistatin-344 has unusually robust preclinical and early clinical evidence:
Mouse studies (Haidet et al., 2008): Single AAV-delivered follistatin-344 produced sustained muscle mass increases of over 20% in both normal and dystrophic mice, lasting 2+ years. FS344 outperformed all other myostatin inhibitors tested.
Nonhuman primates (Kota et al., 2009): AAV1-delivered FS344 increased muscle size and strength in macaques with no adverse immune response and no effect on reproductive hormones.
Human clinical trial (Mendell et al., 2015): Phase 1/2a AAV1.CMV.FS344 gene therapy in Becker muscular dystrophy patients improved 6-minute walk test distance with no serious adverse events and no reproductive hormone changes.
Porcine model (Guo et al., 2017): Transgenic pigs expressing human follistatin-344 showed significantly increased skeletal muscle mass via myofiber hypertrophy.
Stacking Protocols
Stack Components Purpose GH + Myostatin FS-344 50 mcg + CJC-1295/Ipamorelin Myostatin inhibition + GH/IGF-1 Growth Factor FS-344 50 mcg + IGF-1 LR3 Myostatin block + direct IGF-1 receptor activation Connective Tissue Support FS-344 50 mcg + BPC-157 + TB-500 Muscle growth + tendon/ligament adaptation
Stacking tips: No clinical data validates any combinations. Documented starting doses begin around FS-344 alone for at least one cycle before adding partners. BPC-157 and TB-500 are popular protective additions to help tendons/ligaments adapt to increased muscular loading.
Side Effects & Safety
Injection site reactions -- redness, swelling, itching (most common) Transient fatigue -- some users report mild fatigue in first 2-3 days Joint stiffness -- occasionally reported, typically mild Elevated appetite -- consistent with increased metabolic demand Reproductive concerns (theoretical) -- follistatin is involved in FSH regulation, though FS344 has lower FSH-suppressing activity than FS288. No reproductive hormone changes observed in the Mendell clinical trial Tendon/ligament adaptation lag -- rapid muscle growth without proportional connective tissue strengthening may increase injury risk Commonly excluded populations: Trial protocols and community usage guidelines commonly exclude subjects with active malignancy, pregnancy or breastfeeding, autoimmune conditions, or age under 18
mg to Units Conversion
On a standard 100-unit insulin syringe, each "unit" equals 0.01 mL (so 100 units = 1 mL). Once Follistatin-344 is reconstituted, the conversion from a target dose to syringe units depends on the chosen dilution.
The two reconstitution ratios most often described in community protocols are below.
Reconstitution A: 1 mg vial + 2 mL BAC water (500 mcg/mL) — the standard dilution from the Quick Reference above.
Dose (mcg) Volume (mL) Units (insulin syringe) 25 mcg 0.05 mL 5 units 50 mcg 0.1 mL 10 units 75 mcg 0.15 mL 15 units 100 mcg 0.2 mL 20 units
Reconstitution B: 1 mg vial + 3 mL BAC water (333 mcg/mL) — more BAC water for larger, easier-to-measure draws.
Dose (mcg) Volume (mL) Units (insulin syringe) 25 mcg 0.075 mL 7.5 units 50 mcg 0.15 mL 15 units 75 mcg 0.225 mL 22.5 units 100 mcg 0.3 mL 30 units
These conversions reflect the dilutions documented in community reconstitution protocols. They report how the math is described, not a recommended dosing schedule.
Core Supplies for This Protocol
The three essentials for running any reconstituted injectable: cold storage, accurate syringes, and metabolic tracking.
As an Amazon Associate, The Peptide Catalog earns from qualifying purchases.
Full catalog →
Follistatin Peptide Page -- Full profile, vendor pricing Follistatin Benefits -- Myostatin inhibition and beyond Follistatin Results Timeline -- Week-by-week expectations IGF-1 LR3 Benefits Guide -- Growth factor often stacked with follistatin BPC-157 Dosing Guide -- Healing peptide for connective tissue support TB-500 Dosing Guide -- Systemic repair peptide CJC-1295 + Ipamorelin Guide -- GH secretagogue stack Calculate Your Follistatin-344 Cycle Cost -- estimate vials needed and total cost Best Peptides for Muscle Growth (2026) -- all 10 muscle-building peptides ranked
References
Citation Topic PMID Lee & McPherron, PNAS (2001) Myostatin regulation by follistatin 11459935 Haidet et al., PNAS (2008) Long-term muscle enhancement via FS344 gene delivery 18334646 Kota et al., Sci Transl Med (2009) FS344 gene delivery in nonhuman primates 20368179 Mendell et al., Mol Ther (2015) Phase 1/2a FS344 gene therapy in Becker MD 25322757 Guo et al., Transgenic Res (2017) Human FS344 expression in pigs 27787698 Amthor et al., Dev Biol (2004) Follistatin-myostatin binding mechanism 15136138
For educational and research purposes only. This is not medical advice. Follistatin-344 is not approved for human use by any regulatory agency.