PEG-MGF Dosage, half-life & reference guide

Week by week.

What to expect in the first 8 weeks

Onset

Unknown; nothing systemic is reported

Peak effect

Unknown in people or animals

Duration

8–16 weeks per community cycle

1. Day 1–14Animal

   Expect nothing systemic to feel

   Commonly reported in the first weeks: very little beyond the injection site, sometimes local soreness or a fuller feeling in the muscle dosed. That fits what it is meant to be — a local signal to muscle stem cells, not a hormone. Nothing here has been measured in people, so your training log is the only read available.

   The science

   The proposed action is on muscle precursor cells rather than on metabolism: in C2C12 cells the E domain of MGF increased myoblast proliferation while holding back terminal differentiation, and blocking the IGF-1 receptor with an antibody did not stop it (Yang & Goldspink 2002). Kandalla 2011 reported the same peptide activating human muscle progenitor cells and raising their fusion potential across ages. A 2026 clinical review places PEG-MGF in its lowest evidence tier, with no peer-reviewed human studies and no half-life documented (Dominikowski 2026).

   Sources

   • Yang & Goldspink (2002)
   • Kandalla et al. (2011)
   • Dominikowski et al. (2026)

   Updated Oct 2026

2. Day 14–42Animal

   Multiply first, repair after

   As its discoverers describe it, MGF is a sequence, not a bigger push: the tail tells muscle stem cells to multiply and wait, and mature IGF-1 then tells them to fuse and rebuild. That is a repair story rather than a growth story, which is why it is usually run after hard training or an injury rather than as a standing dose.

   The science

   The IGF-1 gene's splicing, processing and the biology of its E peptides are mapped in Philippou 2014. Yang & Goldspink 2002 is the original split: the E domain raised proliferation and inhibited differentiation, where mature IGF-1 does the reverse. Loading is what turns the variant on — muscle raises IGF-1Ec after resistance exercise and damage, and the human Ec peptide itself has been identified in tissue and tracked after exercise-induced muscle damage (Vassilakos 2017). None of this has been tested by injecting the peptide into a person.

   Sources

   • Philippou et al. (2014)
   • Yang & Goldspink (2002)
   • Vassilakos et al. (2017)

   Updated Oct 2026

3. Day 28–84Animal

   Where the animal evidence is actually strongest

   Not muscle growth. The clearest animal results for this peptide are heart function preserved after an induced heart attack, brain tissue protected when blood flow was cut off, and tendon and bone defects healing faster — mostly with synthetic peptide delivered near the injury. Running it for size asks it to do the thing its own evidence covers least.

   The science

   Mavrommatis 2013: a stabilized E-domain peptide (C-terminus amidated, two arginines as D-stereoisomers) entered heart cells without using the IGF-1 receptor, localized to the nucleus, blocked apoptosis, and preserved contractility two weeks after a myocardial infarction in mice. In sheep given microsphere infarcts, the E domain preserved cardiac function with about 35% less compromised muscle than controls (Carpenter 2008). Dluzniewska 2005 found strong neuroprotection from the synthetic peptide in a gerbil model of transient brain ischemia and in hippocampal culture, with the effect independent of the IGF-1 receptor. In connective tissue: Zhang 2016 improved healing of injured rat Achilles tendon, Zhang 2015 traced tenocyte invasion to MMP-2 via FAK-ERK, and Deng 2011 reported faster healing of a 5 mm radius defect in rabbits — while Xin 2012 found the same peptide inhibiting osteoblast differentiation and mineralization, the same proliferate-but-do-not-commit pattern.

   Sources

   • Mavrommatis et al. (2013)
   • Carpenter et al. (2008)
   • Dluzniewska et al. (2005)
   • Zhang et al. (2016)
   • Zhang et al. (2015)
   • Deng et al. (2011)
   • Xin et al. (2012)

   Updated Oct 2026

4. Any dayAnimal

   What PEG-MGF is built on

   A disputed cell finding, a set of local animal injury studies, and no human data. The lab that discovered MGF's effect on muscle cells and two drug companies that set out to repeat it reached opposite answers — the companies found nothing at any concentration they tried, and said so in print. That disagreement is the honest center of this entry; the PEG version has never been studied at all.

   The science

   Yang & Goldspink 2002 reported the proliferation and differentiation effects (an erratum followed in 2006). Fornaro 2014 — two pharmaceutical companies, published jointly — found peptide up to 500 ng/ml failing to raise proliferation in C2C12 cells or primary human myoblasts, failing to inhibit myoblast fusion, doing nothing in primary mouse muscle stem cells, and failing to activate p-ERK in cardiac myocytes, while mature IGF-1 and full-length IGF-1Eb worked in the same hands; they concluded the results "call in to question whether there is a physiological role for MGF". The animal work used synthesized peptide rather than anything a user buys: Mavrommatis 2013 a chemically stabilized analogue, Dluzniewska 2005 a synthetic C-terminal peptide. Esposito 2012 characterized black-market MGF as C-terminally amidated analogues of the human sequence, and Cox 2017 identified a confiscated variant, MGF R23H, stable in plasma and expected to be detectable in urine.

   Sources

   • Yang & Goldspink (2002)
   • Fornaro et al. (2014)
   • Mavrommatis et al. (2013)
   • Dluzniewska et al. (2005)
   • Esposito et al. (2012)
   • Cox et al. (2017)

   Updated Oct 2026

5. With IGF-1 LR3Community

   Two halves of the same gene

   The pairing people reach for is exactly the biology: IGF-1 LR3 is the mature half of the molecule, PEG-MGF the tail the body cuts off it. As MGF's discoverers describe it, the tail recruits muscle stem cells and the mature peptide tells them to build. Both are research-only, and the glucose risk in the pair comes from the IGF-1 side alone.

   The science

   The IGF-1 gene's splice variants produce mature IGF-1 plus an E domain, which is then cleaved (Philippou 2014). In cells the two halves pulled in opposite directions on differentiation: the E domain raised proliferation and held back fusion, mature IGF-1 did the reverse (Yang & Goldspink 2002) — though an independent replication found no effect of the E peptide at all (Fornaro 2014). No study has combined them in any species, and low blood sugar belongs to the IGF-1 arm: IGF-1 lowers glucose and suppresses insulin secretion (Increlex label 2025), while nothing of the kind is documented for the E peptide.

   Sources

   • Philippou et al. (2014)
   • Yang & Goldspink (2002)
   • Fornaro et al. (2014)
   • Increlex label (2025)

   Updated Oct 2026

6. With HGH, CJC-1295 no DAC and IpamorelinCommunity

   With the GH peptides: one pathway, two doors

   MGF comes from the same gene GH acts on, but loading and muscle damage are what is known to turn the splice on; whether GH adds to it is unsettled. The stack is two pushes on one pathway; the GH side is where the felt effects and the side effects come from, and no study has combined the two.

   The science

   GH acts largely by raising IGF-1; whether it also raises local IGF-1 transcripts in tissue is still equivocal (Philippou 2014), while the Ec peptide responds to exercise-induced muscle damage (Vassilakos 2017). Co-activating the GHRH and ghrelin receptors releases GH synergistically in people (Bowers 1990), which is the basis for the CJC plus ipamorelin pairing; what the GH pulse does to MGF expression in a trained adult has not been measured, and no study has combined a GH peptide with injected MGF in any species.

   Sources

   • Philippou et al. (2014)
   • Vassilakos et al. (2017)
   • Bowers et al. (1990)

   Updated Oct 2026

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After week 8

1. Day 84+Animal

   Past twelve weeks, nothing has been studied anywhere

   Community cycles run 8 to 16 weeks with a break. No study in any species has given this peptide for weeks on end, so the long end of a cycle is uncharted rather than cleared. The one long-horizon question worth holding is that the same E peptide turns up in tumor biology, which is a reason for caution rather than an observed harm.

   The science

   The animal experiments were short and local: days to two weeks around an injury (Mavrommatis 2013; Zhang 2016). On the other side of the ledger, the Ec peptide behaved as an autonomous growth signal in human prostate cancer cells and IGF-1Ec expression is preferentially found in cancerous prostate tissue (Armakolas 2010; Armakolas 2015), with altered expression in bladder, thyroid and colorectal tumors too (higher in advanced thyroid cancer, lower in advanced bladder cancer). A 2026 review of these compounds names the proliferative concern explicitly as biologically plausible and unproven (Dominikowski 2026).

   Sources

   • Mavrommatis et al. (2013)
   • Zhang et al. (2016)
   • Armakolas et al. (2010)
   • Armakolas et al. (2015)
   • Dominikowski et al. (2026)

   Updated Oct 2026

Mixing and a typical run.

Safety.

Goes with.

• IGF-1 LR3
• HGH
• CJC-1295 no DAC

Questions people ask.

Research.

Reference.

Cadence

2–3× weekly

2–3x weekly, post-workout

Half-life

Not measured: no pharmacokinetic study of PEG-MGF has been published, in people or in animals. The unmodified peptide is broken down quickly, and for a mouse heart study researchers stabilized it chemically — amidating one end and swapping two arginines for their mirror-image form (Mavrommatis 2013); attaching PEG is a standard way to slow that clearance. The 48-to-72-hour figure community guides quote has never been measured.

Research basis

●●● Emerging

Primarily preclinical / limited human data