PEG-MGF

What is it?

MGF (mechano growth factor) is a form of IGF-1 that muscles make when they are worked hard. "PEG" is a chemical tail added in a lab to make it last longer in the blood. PEG-MGF does not exist in the body.

Why do people use it?

Bodybuilders use it hoping to grow muscle or recover faster. The idea comes from muscle cells in dishes and mouse studies, not from people.

Does it really work?

Unknown. We found no study that gave PEG-MGF to people. In one human study, a hard leg workout raised the body’s own MGF signal in young adults, but not in adults over 70. That tells us about natural MGF, not about the lab product.

Related human data (no PEG-MGF studies in people)

We found 0 studies of PEG-MGF in people. The 3 rows below are related human data. None gave PEG-MGF to anyone.

We read each of these 3 papers on PubMed on October 28, 2026.

Is it safe? Side effects

• The FDA found no data from people using PEG-MGF.
• MGF is part of the IGF-1 family, a growth signal. Nobody has tested what extra amounts do to cancer risk.
• Anti-doping labs have found MGF types in seized vials. What is really inside a vial is unknown.

Is it legal in the US?

PEG-MGF is not an FDA-approved medicine.

• The FDA had put it on its "Category 2" list of risky pharmacy ingredients.
• In April 2026, it was moved off that list because the groups that asked about it withdrew their request. The FDA did not say it is safe.
• Plain MGF is on "Category 3," meaning people asked for it without enough support.
• On October 28, 2026, HHS issued a peptide policy for 6 other peptides. It does not cover PEG-MGF. WADA bans MGFs in sports.

What this means for PEG-MGF

• Leaving Category 2 is not approval. The FDA said it did not judge it safe. (FDA)
• Vials sold "for research" are not medicine. The FDA has warned sellers of such products. (FDA)
• Bringing it into the US for yourself is, in most cases, illegal, the FDA says. (FDA)

Banned in sports? Drug tests

Banned in sports.

Yes. WADA bans PEG-MGF at all times, in and out of competition. It is in section S2.3 of the 2026 list: mechano growth factors (MGFs).

Check work, NCAA, and military rules for PEG-MGF

Talk to your doctor

If you want to build muscle, ask a doctor or trainer about strength training and protein. Those have real studies in people. PEG-MGF has none. We never share doses or tell you where to buy. Print our doctor questions sheet.