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Peptides are short chains of amino acids — the building blocks of proteins — typically containing between 2 and 50 amino acids linked together. They act as signalling molecules in your body, telling cells what to do: when to grow, when to repair, when to release hormones, when to reduce inflammation. Your body makes thousands of peptides naturally, and synthetic versions of some of these are used in medicine and compounded therapy.
You’re hearing about peptides because they’ve moved from research labs and sports medicine into mainstream health discussions — particularly around metabolic health, skin health, recovery, and longevity. The term itself is confusing because it covers everything from insulin (a naturally occurring peptide hormone your body makes) to newer compounded preparations like BPC-157 or CJC-1295. Understanding what peptides actually are at a molecular level helps you make sense of what they can and can’t do, and why the regulatory environment around them is complex.[1]
Biochemically, peptides sit between individual amino acids and full proteins. When amino acids link together through peptide bonds, chains of 2–50 amino acids are called peptides; longer chains (typically over 50) are called proteins. This is an arbitrary cut-off, but it’s the convention.[2] The key functional point is that peptides are small enough to be synthesised relatively easily in a lab, but large enough to carry specific biological instructions.
Your body uses peptides for cell-to-cell communication. Hormones like insulin, glucagon, oxytocin, and growth hormone-releasing peptides are all naturally occurring peptides. Antimicrobial peptides are part of your immune system. Neuropeptides regulate pain, mood, and appetite. The human genome encodes thousands of these signalling molecules, and we’ve only characterised a fraction of what they do.[3]
In medicine, peptide-based drugs have been used for decades. Insulin (discovered in 1921, still a peptide) is the most famous example. GLP-1 receptor agonists — semaglutide (Ozempic, Wegovy), liraglutide (Victoza, Saxenda), tirzepatide (Mounjaro, Zepbound) — are all peptides. These are SAHPRA-registered medicines with extensive clinical trial data.[4] Other peptides, particularly those used in compounded form (BPC-157, CJC-1295, ipamorelin, sermorelin, thymosin beta-4, GHK-Cu), do not have the same level of human evidence. Some have promising animal data or small human trials; others have almost no published research outside of athletic or bodybuilding contexts.[5]
The therapeutic appeal of peptides is their specificity — in theory, a peptide can be designed to bind to a particular receptor and trigger a particular cellular response, with fewer off-target effects than small-molecule drugs. The challenge is delivery: peptides are broken down quickly by enzymes in the gut and bloodstream, which is why many are given by injection (subcutaneous or intravenous) rather than orally.[6]
When a patient asks me about peptides, the first thing I clarify is which peptide we’re talking about, because the term covers medicines with rock-solid evidence (insulin, semaglutide) and experimental compounds with thin or no human data (MOTS-c, epitalon, KPV). The regulatory status matters enormously: registered medicines have been through Phase III trials and post-marketing surveillance; compounded peptides have not.
For registered peptide medicines, the clinical approach is standard: assess indication, contraindications, drug interactions, patient preferences, and prescribe if appropriate. For unregistered or compounded peptides, the approach is more cautious. I look at what published evidence exists (PubMed, not wellness blogs), whether the proposed use is biologically plausible, what the safety data shows, and whether the patient understands they’re using something outside the registered-medicine framework.
In South Africa, compounded peptides are supplied under Section 21 of the Medicines Act — meaning they’re prepared by a registered pharmacy for an individual patient on the basis of a specific prescription. They are not registered medicines. SAHPRA law prohibits pharmacies and prescribers from making claims about the safety, quality, or efficacy of unregistered medicines in advertising or promotional material, which is why you’ll see careful language around compounded peptides in clinical practice.[7]
The practical questions I weigh: Is there a registered alternative that does the same thing with better evidence? (Often, yes.) Is the patient’s concern one where peptide therapy has a plausible mechanism and at least some human data? (Sometimes.) Is the patient aware of the evidence gaps and comfortable proceeding on that basis? (This is the informed-consent conversation.)
Dosing, frequency, injection technique, storage (most peptides require refrigeration), and monitoring are all part of the clinical plan. Peptides are not supplements you add casually — they’re biologically active signalling molecules, and they need to be used under medical supervision.
If you experience unexpected symptoms after starting any peptide — significant injection-site reactions beyond mild redness, allergic symptoms (rash, swelling, difficulty breathing), new or worsening health concerns, or anything that doesn’t match what your prescriber told you to expect — contact your prescriber immediately. Do not adjust doses on your own, and do not source peptides from unregulated suppliers (the counterfeit and contamination risk is real, particularly for weight-loss peptides).
Peptides that are not registered medicines in South Africa (which includes most compounded preparations) are governed by Section 21 of the Medicines and Related Substances Act. This means they can be prescribed and supplied, but only on an individual patient basis, and no general marketing or outcome claims are permitted. Registered peptide medicines (insulin, semaglutide, liraglutide, tirzepatide) are governed by their approved indications, and off-label prescribing follows standard medical practice.
Peptides are short amino-acid chains that function as signalling molecules in your body. Some are well-established, registered medicines with decades of clinical use; others are experimental compounds with limited human evidence. If you’re considering peptide therapy for a specific concern, the right next step is understanding which peptide is being proposed, what the evidence base is, and whether it’s appropriate for your situation — and that’s a conversation with a registered medical practitioner, not something you figure out from an article.