PEG-MGF

PEG-MGF is a lab-made peptide related to IGF-1, a growth signal in the body ^[21]. MGF stands for mechano growth factor ^[20]. That name is used for a form of IGF-1 that muscle makes after strain or injury ^[20]. It is also used for a short lab-made peptide copied from one end of that form ^{[20] [16]}.

PEG-MGF is MGF with a chemical chain called PEG attached, which is what pegylated means. FDA calls it mechano growth factor pegylated ^[1]. Plain MGF, without PEG, is a different substance, and FDA lists it apart ^[2].

A 2026 review groups PEG-MGF with peptides sold online as research compounds for muscle and sport ^[21]. A US sports drug-testing lab found a different MGF variant in seized vials ^[19].

PEG-MGF is in limbo: FDA lists it as withdrawn from Category 2, and it has not added it to Category 1 ^{[1] [2]}. That is not approval, and it does not make compounding lawful. Checked 25 October 2026.

Category 2 is FDA's list of substances that may raise significant safety risks ^[1]. Category 1 is the list of substances under review that pharmacies may use while FDA decides ^[3]. In April 2026, the groups that nominated PEG-MGF withdrew, so it came off Category 2 ^{[1] [8]}. Taking a substance off Category 2 does not by itself let pharmacies use it ^{[8] [9]}.

FDA's 503A list of 14 May 2026 names plain MGF, without PEG, in Category 3 ^[2]. That category holds substances nominated without enough support ^[2]. Plain MGF is a different substance, so its place on the list says nothing about PEG-MGF.

FDA's notice says its Pharmacy Compounding Advisory Committee will discuss PEG-MGF before the end of February 2027 ^[4]. The notice gives no exact date and no meeting materials ^[4]. Law and trade reports give the same time frame ^{[8] [22]}. The committee gives advice only. FDA decides by writing a rule ^[8].

A June 2026 pharmacy column expected PEG-MGF to stay restricted ^[23]. FDA's own page lists it as withdrawn from Category 2 ^[1]. The FDA page is what this page follows.

Until FDA acts, a pharmacy may not use PEG-MGF under the federal compounding law ^{[3] [5]}.

The evidence grade is insufficient: we found no published study of PEG-MGF itself, in people or in animals. FDA found no data on any person given it ^[1]. Every study below used a different form of MGF. A study of a related molecule does not show what PEG-MGF does.

Animal studies of other forms of MGF: in sheep after a heart attack, a piece of MGF kept the heart pumping better than in untreated sheep ^[11]. In mice after a heart attack, a lab-made MGF peptide slowed the decline in heart function ^[12]. In injured mouse muscle, MGF did not help muscle fibers regrow, but it did reduce scarring ^[13]. In rats with an injured Achilles tendon, a lab-made MGF peptide helped the tendon heal ^[14]. In mice with a disease like ALS, an MGF gene, not the peptide, helped muscle strength and nerve cell survival ^[15]. A result in an animal does not show what happens in people.

Lab studies: in 2014, scientists at two drug companies could not repeat the claimed effects of the MGF peptide on muscle cells ^[16]. A 2016 lab test found that the short MGF peptides did not switch on the IGF-1 receptor ^[17]. A full-length form of MGF did ^[17]. A 2010 review says no natural MGF peptide has been found in cells or tissue ^[20].

A 2026 review says the claimed muscle and performance benefits of these peptides remain uncertain ^[21].

There is no legal way to get PEG-MGF in the US today ^{[1] [2]}. In 2020, FDA said no approved drug contains it ^[5]. A pharmacy may use a substance with no official quality standard only if it is in an approved drug or on the federal list ^[5]. PEG-MGF is neither, and FDA is still deciding whether to add it ^{[2] [4]}.

Any open trial would appear in the trials block below, with the date the registry was last checked.

A 2026 review says PEG-MGF is among peptides sold as "research compounds" that people take on their own ^[21]. It warns that what such products contain is uncertain ^[21]. FDA has warned a seller of research-use peptides that a "research use only" label does not stop a product from being a drug ^[7]. That letter did not name PEG-MGF ^[7].

Pharmacies are the other channel a federal record names ^[5]. In 2020, FDA warned a compounding pharmacy that its PEG-MGF products did not meet the rules for compounding ^[5]. Later that year, the pharmacy pleaded guilty to a federal charge of selling unapproved new drugs, PEG-MGF among them ^[6]. FDA warns that PEG-MGF made by a pharmacy may set off the immune system ^[1].