For laboratory and research use only. Not for human consumption.
Growth Hormone

PEG-MGF

Also known as: Pegylated MGF, PEGylated Mechano Growth Factor, Mechano Growth Factor, Pegylated, PEG Mechano Growth Factor

Research
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Key Facts: PEG-MGF

Category
Growth Hormone
FDA Status
Not FDA Approved
Clinical Status
Not FDA approved for any use. FDA placed "Mechano Growth Factor, Pegylated (PEG-MGF)" in 503A Category 2 (significant safety risks) in 2023, then removed it in April 2026 because the nomination was withdrawn, not because safety was established. As of FDA's May 14, 2026 update it does not appear in any 503A category, and it is not on the list of substances pharmacies may compound from. FDA has indicated it plans to consult its compounding advisory committee before the end of February 2027. No registered clinical trials found. WADA: prohibited at all times under S2.3, which bans mechano growth factors (MGFs) on the 2026 List.
Banned in Sport (WADA)
Prohibited at all times under WADA S2 (growth factors), where mechano growth factors (MGFs) are named.
Administration
Subcutaneous or intramuscular injection (forum-reported)
Typical Dose
200-400 mcg 2-3x per week (forum-reported)
Frequency
2-3x weekly in forum protocols
Duration
Forum protocols describe 8-16 week cycles with about 4 weeks off; no studied duration exists
Also Known As
Pegylated MGF, PEGylated Mechano Growth Factor, Mechano Growth Factor, Pegylated, PEG Mechano Growth Factor

How does PEG-MGF work?

Pegylation is a real, well-understood drug technique: attaching PEG makes a molecule bigger, slows how fast the kidneys clear it, and shields it from enzymes. It works for approved drugs, and a pegylated version of full IGF-1 (a different molecule) showed a half-life of 140 to 200 hours in a 2017 first-in-human study. The pitch for PEG-MGF is that the same trick lets the short-lived MGF peptide circulate long enough to act on muscle throughout the body. But PEG also changes how a molecule binds and where it goes, so effects reported for unmodified MGF cannot simply be assumed to carry over. The 2026 review made exactly that point. And since the underlying MGF mechanism was not reproduced in a 2014 pharma study, PEG-MGF is a modification of a hypothesis.

What does the research show?

Searching PubMed for PEG-MGF returns essentially one relevant hit: a 2026 narrative review in Frontiers in Endocrinology (Dominikowski and colleagues) on performance peptides that target the GH and IGF-1 axis. It rated PEG-MGF tier D: no peer-reviewed human studies, no reported route of administration in clinical research, half-life not reported, and safety concerns that are theoretical (based on MGF's link to cancer-cell growth in lab studies). The doses that circulate come from bodybuilding forums, which the review summarized only so doctors can recognize what patients are doing, not as guidance. Everything else people cite is MGF research: cell and animal studies suggesting muscle and heart repair effects, plus a careful 2014 study by Fornaro and colleagues that found no effect of MGF on muscle cells, and no effect of native or stabilized MGF on a separate signaling readout in heart cells. If you are looking for evidence that PEG-MGF builds muscle in humans, it does not exist yet.

Trial Progress:Preclinical
Pre
I
II
III
IV
FDA

What doses have been studied?

Limited Research·No published studies on the pegylated form; claims are extrapolated from MGF lab work

Typical Dosingⓘ

Community experience

Common Dose

200-400 mcg 2-3x per week (forum-reported)

Range

100-400 mcg per injection (forum-reported)

Frequency

2-3x weekly in forum protocols

There is no human research dose for PEG-MGF. These numbers exist only because a 2026 clinical review catalogued bodybuilding-forum protocols so doctors could recognize them, and the authors stated they must not be read as validated or safe. Forum protocols often time injections 30-60 minutes after training.

Research Dosingⓘ

Scientific studies

No published research doses exist for PEG-MGF. The figures below are bodybuilding-forum protocols as summarized by a 2026 clinical review, which stressed they are not validated or safe.

Duration

Forum protocols describe 8-16 week cycles with about 4 weeks off; no studied duration exists

Administration

Subcutaneous or intramuscular injection (forum-reported)

When and how is PEG-MGF taken?

Best Time to Take

Not established (forums suggest post-workout)

Forum-reported 2-3 times weekly; no studied frequency

Food Recommendation

With or without food

Why This Timing?

Forum protocols time it 30-60 minutes after training on the theory that MGF matters most after muscle loading. No study has tested whether timing matters for the pegylated form.

What are the side effects of PEG-MGF?

Not everyone experiences these effects. Individual responses vary based on dosage, duration, and personal factors.

  • ●No human safety data exists
  • ●Injection site reactions
  • ●Theoretical cancer-growth concern (MGF E-peptide stimulated prostate cancer cells in the lab)
  • ●Possible low blood sugar is a theoretical concern for IGF-1 analogues
  • ●Unknown effects of the PEG chain with repeated use
  • ●Product composition is unverified in unregulated supply
  • ●Banned in tested sport (WADA S2)

References

Research This Peptide Further

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Frequently Asked Questions

What does PEG-MGF do?

PEG-MGF is MGF (the synthetic E-domain peptide from the IGF-1Ec splice variant) with a polyethylene glycol chain attached to make it last longer in the body. That is the theory, anyway. We have to be blunt: there is essentially no published research on PEG-MGF itself. A 2026 clinical review of growth-axis peptides put it in its lowest evidence tier, with no peer-reviewed human studies and no published half-life. Everything said about it online is borrowed from MGF lab work, and MGF's own evidence is shaky.

How does PEG-MGF work?

Pegylation is a real, well-understood drug technique: attaching PEG makes a molecule bigger, slows how fast the kidneys clear it, and shields it from enzymes. It works for approved drugs, and a pegylated version of full IGF-1 (a different molecule) showed a half-life of 140 to 200 hours in a 2017 first-in-human study. The pitch for PEG-MGF is that the same trick lets the short-lived MGF peptide circulate long enough to act on muscle throughout the body. But PEG also changes how a molecule binds and where it goes, so effects reported for unmodified MGF cannot simply be assumed to carry over. The 2026 review made exactly that point. And since the underlying MGF mechanism was not reproduced in a 2014 pharma study, PEG-MGF is a modification of a hypothesis.

Is PEG-MGF FDA approved?

No, PEG-MGF is not currently FDA approved. Current status: Not FDA approved for any use. FDA placed "Mechano Growth Factor, Pegylated (PEG-MGF)" in 503A Category 2 (significant safety risks) in 2023, then removed it in April 2026 because the nomination was withdrawn, not because safety was established. As of FDA's May 14, 2026 update it does not appear in any 503A category, and it is not on the list of substances pharmacies may compound from. FDA has indicated it plans to consult its compounding advisory committee before the end of February 2027. No registered clinical trials found. WADA: prohibited at all times under S2.3, which bans mechano growth factors (MGFs) on the 2026 List.

Is PEG-MGF banned in sport?

Prohibited at all times under WADA S2 (growth factors), where mechano growth factors (MGFs) are named.

What are the side effects of PEG-MGF?

Reported side effects include: No human safety data exists, Injection site reactions, Theoretical cancer-growth concern (MGF E-peptide stimulated prostate cancer cells in the lab), Possible low blood sugar is a theoretical concern for IGF-1 analogues, Unknown effects of the PEG chain with repeated use. Individual responses vary based on dosage, duration, and personal health factors.

What is the typical dose of PEG-MGF?

Community-reported common dose: 200-400 mcg 2-3x per week (forum-reported) (2-3x weekly in forum protocols). Range: 100-400 mcg per injection (forum-reported). Administration: Subcutaneous or intramuscular injection (forum-reported). Community-reported doses. Not medical advice. Consult healthcare provider.

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GHRP-6 is a synthetic six-amino-acid peptide (His-D-Trp-Ala-Trp-D-Phe-Lys-NH2) that tricks the body into releasing its own growth hormone. It was one of the first growth hormone secretagogues ever made, and the hunt to find out why it worked led scientists straight to the discovery of ghrelin. It has no approval as a drug anywhere and is used only as a research compound.

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