A growing global trend of unregulated, banned peptide injection among fitness enthusiasts and aspiring bodybuilders is raising urgent red flags from medical and scientific experts, who warn the untested practice carries severe, underreported health risks.
For 29-year-old aspiring bodybuilder Thomas (a pseudonym to protect his identity), based in France where the substances he uses are outlawed, injecting peptides has become a fixed part of his daily routine. Every evening at 9:30 p.m., his phone alarm reminds him to mix and self-administer two banned synthetic peptides into his lower abdomen: daily doses of GHK-Cu, which he says improves skin quality, and Retatrutide, taken three times weekly to curb appetite. Six months after first trying peptides while already using steroids, Thomas has added two more unapproved substances to his regimen: Selank to ease anxiety, and BPC-157, marketed to speed up soft tissue and ligament repair after gym workouts.
Since France bans the sale and use of these peptides, no official dosage guidelines or safety protocols exist. Like hundreds of other mostly male users, Thomas gets his advice from anonymous online communities on Reddit and Discord, where users swap anecdotes about dosing and claimed benefits. “It takes a little organisation, but it’s become a routine,” Thomas told Agence France-Presse, adding he dismisses warnings of risk, which he calls “rare and not serious.”
Thomas is far from alone. Driven by viral social media content from influencers, celebrities and the unregulated wellness industry, peptides are being widely marketed as a miracle solution for everything from anti-aging and clearer skin to muscle growth, improved sleep and sharper cognitive function. The narrative of “biological optimization” pushed online frames the human body as a form of capital that can be upgraded with chemical supplements, attracting growing numbers of people willing to self-experiment with untested substances.
Peptides themselves are not inherently dangerous: short chains of amino acids that form proteins, they occur naturally in the human body and regulate critical processes like tissue repair. Lab-synthesized peptides are also approved as active ingredients in many common medications, including insulin and popular GLP-1 weight loss drugs. But the unregulated, unauthorized versions sold via gym networks and online marketplaces have never undergone rigorous clinical testing to confirm their claimed benefits or safety.
French national research institute INSERM stresses that no large-scale, randomized controlled human trial has ever validated the sweeping benefits marketed for unapproved peptides. Neuroscientist Armelle Rancillac of INSERM noted most of these compounds have never even been tested on human subjects, leaving even experienced users with no accurate understanding of correct dosing or long-term side effects. Claims from online self-experimenters, she argued, are scientifically worthless and are given far too much credibility by audiences eager for quick physical results.
The warnings are backed by documented hospitalizations linked to unregulated peptide use. Earlier this year, Australian health authorities confirmed six cases of acute liver injury directly tied to Retatrutide-containing products. While exact data on how many people use unapproved peptides is hard to collect, Swiss University of Lausanne sports sociologist Fabien Ohl told AFP the sharp rise in exposure alone is enough to “raise alarm.”
Ohl also criticized the harmful ideological underpinning of the trend: the online framing of masculinity that ties male worth to physical optimization via chemical enhancement, which he says normalizes a dangerous ideal of “the biological male who is potentially more violent and aggressive.”
The regulatory landscape around peptides remains fractured. Many countries, including France, ban unapproved synthetic peptides entirely due to safety concerns, but the issue has become contentious in the United States. Last month, a federal advisory panel made a controversial recommendation to loosen restrictions on a range of unapproved peptides. The decision drew fierce backlash from the medical community, which accuses US Health Secretary Robert F. Kennedy Jr. — an avowed public user and fan of peptides — of stacking the panel with industry-linked allies to push for deregulation.