The wild success of GLP-1 weight-loss drugs – spelled out, glucagon-like peptide-1 drugs – was an early indication of today’s TikTok-driven peptide craze. GLP-1-receptor agonists like Wegovy could activate a receptor like a hormone would – e.g. like the naturally occurring GLP-1 hormone produced by the gut. Zepbound, which came later, was a dual agonist that could act on the receptors for both GLP-1 and GIP (glucose-dependent insulinotropic polypeptide) hormones. However, while 100+ peptides are FDA-approved (e.g. insulin, oxytocin, semaglutide, tirzepatide), many of the popular peptides used by fitness and wellness influencers are not. The Trump administration – with US Secretary of Health and Human Services (HHS) Robert F Kennedy (RFK) Jr as frontman – seems poised to change this landscape.

What are peptides? Peptides are short chains of about 2 to 50 amino acids, the unique sequence of which determines the peptide’s properties. The defined set of 20 amino acids are the building blocks of proteins, which are also known as polypeptides. Proteins are larger than peptides and can be 50 to 2000 amino acids long. Peptides are typically linear, unstructured fragments, whereas proteins spontaneously fold into a unique 3D shape that helps determine its function (e.g. how it binds with other molecules) and how it can be used.

Why makes peptides particularly useful? Because peptides are smaller than proteins, they can be much more easily absorbed by the body. For instance, collagen peptides – manufactured by breaking down collagen protein (e.g. from cattle bones or fish) into shorter amino-acid chains using hydrolysis – is widely used for skin and joint health because of its low molecular weight and bioavailability.

Most hormones and some neurotransmitters – the biochemical messengers of the body – are made of peptides/proteins. Peptides are useful in the messenger role because their similarity to proteins means they can circulate in the blood without a protein carrier, they can be quickly synthesized and rapidly cleared (given their short half-life), and their chemical diversity (based on permutations of 20 amino acids) allows for highly specific targeting of receptors. There are 7000+ natural peptides in the body, and some are already regulating a vast array of biological processes such as homeostasis, energy metabolism, growth, stress, inflammation, immune response, and tissue repair.

Influencers are touting and claiming dramatic effects from peptides like BPC-157 and TP-500 (Thymosin Beta-4) for injury recovery; GHK-Cu (the “pretty peptide”) for anti-aging and skincare; KPV for inflammation and gut health; Melanotan II for tanning and rosacea; and Epitalon for sleep; among others. These peptides are particularly popular within certain communities, such as bodybuilding, “looksmaxxing” young men, biohackers, and tech. Companies are branding peptide “stacks” (e.g. KLOW) that might include 4 or more peptides. With a cost per peptide injection typically ranging from $225 to $1170, peptides have become a lucrative business.

While peptides can be consumed orally, many of this emerging class of peptides are injectables. The reason for this is that oral peptides need to make their way through the digestive system, which means peptide-based pills need a much higher dose than injectables. For instance, Novo Nordisk’s Wegovy pill has a 10x higher dose than its injectables, which means it needs to make much more of the main ingredient and the pill has lower gross margins. Topical peptides have limited penetration into the skin without enhancers, generally performing worse than oral peptides. This generally leaves injectables, which piggyback on consumers’ growing familiarity with injectable weight-loss drugs.

Before 2023, popular peptide treatments were frequently produced by 503A compounding pharmacies, which were required to tie formulations to patient-specific prescriptions although some 503A pharmacies were effectively doing small-scale manufacturing. Many peptides had ambiguous status rather than being on a “positive list” – either the very short 503A Bulks List or classified as Category 1, which is the “Under Evaluation” category that uses the FDA’s enforcement discretion to allow for compounding. In late 2023, the US Food and Drug Administration (FDA) under the Biden administration designated 19 peptides as 503A Category 2 – “Bulk Drug Substances that Raise Significant Safety Risks” – a “negative list” that effectively bars them from being compounded. The Biden administration’s move in 2023 spurred a gray market in which these peptides continued to be sold “for research purposes only” or “not for human consumption,” often by Chinese suppliers.

In Feb 2026, RFK Jr went on the Joe Rogan podcast and revealed that he was a “big fan of peptides,” having used them himself. In Apr 2026, 17 peptides were withdrawn by nominators from Category 2. Around the same time, RFK Jr announced that 12 of the original list of 19 peptides designated as Category 2 would be reviewed at the FDA Pharmacy Compounding Advisory Committee (PCAC)’s next two meetings (Jul 23-24 and another meeting before Feb 2027). The reviews will likely be with an eye towards clearing the peptides for compounding (e.g. 503A Bulks List, or more likely, Category 1). The upcoming July 2026 meeting will review 7 peptides – BPC-157, Emideltide (DSIP), Epitalon, KPV, MOTS-C, Semax (heptapeptide), and Thymsin Beta-4. The following meeting will review the remaining 5 of the 12 – GHK-Cu (injectable), Dihexa acetate, Ibutamoren mesylate, Melanotan II, and Cathelicidin LL-37.

Most of these popular peptides lack clinical evidence of efficacy based on randomized trials. Clinical trials are expensive, and naturally occurring amino-acid sequences are hard to patent. Peptides also degrade quickly in the body, requiring chemical modification (at high cost) or repeated injections (requiring patient compliance). RFK Jr is advocating for a permissive stance with respect to peptides, where efficacy is largely put aside and safety is elevated as the primary factor. However, providers and other industry watchers have raised concerns about risks such as hormonal imbalances, immune reactions, growth hormones spurring precancerous cells, contaminated formulations from unlicensed sources, long-term toxic effects on kidneys and other organs, incorrect dosing, and drug interactions. Some peptides have also been banned by international sports authorities as doping substances.

Despite the current chaotic market, peptide therapies and supplements are promising enough that we should expect outsized growth. One source is projecting that peptides will become a $106B market by 2033. Growth could come through FDA-approved drugs, 503A/503B Bulks List and Category 1 compounded formulations, or the continuation of gray-market peptides. The DrugBank database, for instance, lists 600+ peptide compounds at varying stages, and peptide startups (e.g. Superpower, Noho Labs, Unnatural Products, Enhanced, Protocole) seem to be everywhere right now. We could see an inflection point in the market after the PCAC meeting in July, if the peptides under review are cleared. In the meantime, the Trump administration’s HHS seems to have little appetite for enforcement anyway.

Sep 19 2025 (3 Shifts): GLP-1 weight-loss drugs in pill form

Dec 9 2022 (3 Shifts): Semaglutide-mania, compounding pharmacies, and direct-to-consumer healthcare