The Australian Drug Foundation has published an explainer arguing that peptides promoted online as quick fixes for weight loss, muscle growth and anti-aging mostly lack the research to back those claims. Its central move is a split: some peptide medicines are approved, regulated and prescribed, while a parallel market of unapproved injectables is sold online illegally.

Peptides are short chains of amino acids found naturally in the body, acting as chemical messengers in metabolism and appetite, hormone activity, tissue repair and skin health. Insulin is one. So is GLP-1, made in the gut after eating, which the ADF describes as boosting insulin release, slowing digestion and signaling the brain to feel full.

Two markets, one word

On the approved side sit prescription medicines listed on the Australian Register of Therapeutic Goods: semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro) for type 2 diabetes and weight management, plus insulin and human growth hormone. The Therapeutic Goods Administration has assessed their quality, safety and effectiveness, and they require a prescription.

On the other side are products the TGA has not approved, sold as injectables online. The ADF names retatrutide for weight loss, GHK-Cu for skin, BPC-157 for injury repair and gut health, TB-500 for recovery, and CJC-1295 for muscle growth.

Where the numbers land

The scale of the promotion is the striking figure: as of April 2026, TikTok content tagged with the peptides hashtag had passed 230 million views. Sellers, the ADF notes, often attach "for research use only" disclaimers to shift liability, and influencer posts do not always disclose sponsorship.

Recent testing of three products sold online as retatrutide found actual peptide content ranging from around half to almost double the labeled dose. In Victoria, seven cases of acute liver injury were reported between January and August 2026 among people who had used an unapproved product sold as retatrutide.

Bottom line

This is not an anti-peptide document, which is what makes it useful. It distinguishes clearly between compounds assessed by a regulator and compounds shipped by a website, and it is honest that for the second group the long-term effects are simply not known.

What remains unsettled is enforcement. The ADF says the growth of online suppliers has outpaced regulation, and notes the TGA issued warnings to advertisers and sellers and reported increased enforcement action in 2026.