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Follistatin 344 vs PEG-MGF

Updated 13 sources

Key differences

  1. 1Different levers: follistatin binds myostatin and activin; PEG-MGF is a piece of an IGF-1 isoform tied to repair signalling.
  2. 2Some black-market vials sold as follistatin contained MGF.
  3. 3Different levers. Follistatin removes the myostatin brake on muscle growth; PEG-MGF is a piece of an IGF-1 isoform tied to muscle repair signalling.
  4. 4Black-market follistatin vials have turned out to contain MGF instead.

Side by side

Facts from each record, in the same words as their own pages.
Follistatin 344 and PEG-MGF side by side
Follistatin 344PEG-MGF
Category
  • Other
  • Healing & recovery, GH axis
Evidence
  • Limited human data
  • Animal data only
FDA status
  • Not FDA approvedRegulatory
  • Not FDA approvedRegulatory
WADA
  • Prohibited
  • Prohibited
Half-life
  • Native FS315 had PK poorly suited to an injected drug in a Lilly study; an Fc-fused version had about 100-fold longer terminal half-life. No human figure.Clinical study
  • About 90 minutes for FS344, per one guide, with no source given.Competitor guide
  • 2 to 4 hours for recombinant protein, per another guide.Competitor guide
  • About 35 hours, per a third guide, with no source given.Competitor guide
  • Not reported in any peer-reviewed study, human or animal.Clinical study
  • Several hours, by one guide's estimate; plain MGF about 5 to 7 minutes. No human PK study exists.Competitor guide
  • Community estimates of up to about 1 day; the guide notes no published human PK data.Competitor guide
  • About 5 days, per one guide, with no source given.Competitor guide
Routes
  • Subcutaneous injection, Intramuscular injection
  • Subcutaneous injection, Intramuscular injection
Forms
  • Vial (powder)
  • Vial (powder)
Reported doses
  • 50 to 500 mcg (subcutaneous injection)
  • 1 to 2.5 mcg/kg (subcutaneous injection)
  • 50 mcg (intramuscular injection)
  • 100 to 500 mcg (subcutaneous injection)
  • 200 to 400 mcg (intramuscular injection)
Most cited frequency
  • Once daily
  • 2 to 3 times a week, after workouts
Vial sizes
  • 1 mgCompetitor guide
  • 2 mg, 5 mgCompetitor guide
Mixed vial keeps
  • Fridge at 2 to 8 °C for 7 to 14 days; the guide suggests finishing within 7 days and freezing extra aliquots at -20 °C for up to 30 days.Competitor guide
  • Fridge at 2 to 8 °C, use within 30 days.Competitor guide
Protocols on file
  • 12
  • 10

Doses shown are what sources report, labelled by origin. Not medical advice.

Read each in full

Sources

13 sources, each checked by date. Record updated Oct 24, 2026. Numbers are restated in our own words and labelled by where they came from.

Regulatory2

  1. 503A bulk drug substance categories (May 14, 2026)FDA · checked Oct 24, 2026
  2. Certain bulk drug substances, safety risksFDA · checked Oct 24, 2026

Competitor guide6

  1. Follistatin 344 dosage guidePeptidesExplorer · checked Oct 24, 2026
  2. Follistatin dosing protocolsPeptide Protocol Wiki · checked Oct 24, 2026
  3. Follistatin 344PeptIQ · checked Oct 24, 2026
  4. PEG-MGF dosing protocolsPeptide Protocol Wiki · checked Oct 24, 2026