Peptides, explained by the evidence.

Synthetic pentadecapeptide from a gastric protein. Striking animal results; no controlled human trials.

GLP-1 receptor agonist. Among the most-studied molecules of the decade; approved for diabetes and obesity.

Triple GIP / GLP-1 / glucagon agonist. Two phase 3 obesity trials, a phase 3 diabetes trial and two phase 3 sleep-apnoea trials are published; a head-to-head against semaglutide is topline; not approved anywhere.

Dual GIP / GLP-1 agonist. Approved; beat semaglutide in a direct head-to-head trial.

GHRH analogue. Approved for one narrow indication; the general-population claims are extrapolation.

Selective GH secretagogue. One real randomised trial in humans — and it was negative.

Copper-binding tripeptide. Modest human evidence for topical skin use; injected use has none.

Synthetic tetrapeptide from a Russian gerontology institute. The human studies mostly tested a different product.

Fragment of thymosin beta-4. Human trials exist only as an eye drop; the injectable use has none.

Long-acting amylin analogue. Strong phase 3 data in combination with semaglutide; not yet approved.

Russian-developed heptapeptide, registered in Russia, unstudied elsewhere.

Russian anxiolytic peptide, registered in Russia. Same evidence problem as Semax.

An approved medicine — for one indication, in one population, with a 40% nausea rate.

Was an approved medicine for diagnosing growth-hormone deficiency in children. Withdrawn commercially; adult use is off-label with thin data.

Long-acting GHRH analogue. Raises growth hormone for days; development stopped and no outcome trial exists.

A fat-loss peptide that was properly tested in humans — and failed.

Mitochondrial-derived peptide with striking mouse metabolic data and no human trial.

First-generation daily GLP-1 receptor agonist. Approved for diabetes and obesity; generics arriving.

GLP-1/glucagon dual agonist. Phase 3 published for obesity and liver disease; not yet approved.

GLP-1/glucagon dual agonist. Approved in China for obesity and type 2 diabetes; phase 2 elsewhere.

Reproductive-axis neuropeptide. Small academic trials in fertility and low sexual desire; not approved.

Immune-modulating thymic peptide. Approved in China and ~30 other countries; failed its largest trial.

The human cathelicidin antimicrobial peptide. Two randomised wound-healing trials; not approved.

Mitochondria-targeting tetrapeptide. Newly approved for one ultra-rare disease after a decade of failed trials in bigger ones.

A real hormone with a real injectable licence — and a nasal-spray reputation its trials do not support.

A tanning-and-erection peptide with real small-trial signals and real, documented harms.

A potent GH-releasing peptide whose effect fades with continued use — and that was never developed further.

A GH-releasing peptide approved in Japan as a diagnostic — not as the muscle drug it is sold as.

The original GH-releasing peptide — a good diagnostic tool, an unproven physique drug.

Not a peptide, but sold in the same market — supplements that raise a coenzyme, with clinical benefit still unproven, and a negative phase 3 trial in Parkinson's disease.

An anti-inflammatory tripeptide with real mouse data and no human trial at all.

A mitochondria-encoded peptide with striking lab biology and only observational human data.

A potent synaptogenic molecule in rodents, and nothing at all in humans.

A metabolic enzyme inhibitor with mouse fat-loss data and no human trial.

The first oral small-molecule GLP-1 agonist, approved in the US for weight management in April 2026, licensed in the UK in August 2026 and recommended for EU authorisation in October 2026. A pill, not an injection — and not a peptide.

A GLP-1 and amylin agonist in one molecule, now named zenagamtide. The largest early-phase weight loss yet reported — in 125 people; two phase 2 diabetes trials published since.

An approved medicine for growth-hormone deficiency, and the original anti-ageing drug the evidence does not support.

A real fertility medicine, and the subject of one of the most thoroughly refuted weight-loss claims in medicine.

The body's main antioxidant, sold by injection for skin lightening on inconclusive evidence.

A laboratory reagent sold as a muscle drug. No human trial has ever tested it.

A sleep peptide that was actually tested in insomnia in the 1980s — and mostly did not work.

An oral, non-peptide growth-hormone secretagogue — the one with a year-long randomised trial, which found more lean mass and no less fat.

Once-weekly GLP-1 medicine approved since 2014. A cardiovascular-outcomes trial in nearly 10,000 people; weight loss well below the newer drugs.

The first GLP-1 medicine, from lizard venom, approved in 2005. Neutral in its cardiovascular trial; negative as a Parkinson's treatment.

The natural hormone at the top of the reproductive axis. A licensed diagnostic and fertility treatment — and a TRT-clinic add-on with no trial for that use.

The original tanning peptide — which became an approved medicine for a rare light-sensitivity disease, as a 60-day implant.

An approved obesity peptide — for a few thousand people worldwide with specific genetic defects, on trials of ten and eleven patients.

A myostatin-blocking protein sold as a muscle-building injection. The only human data is a six-patient gene-therapy trial — of a different thing.

A Russian dipeptide-derived nootropic, registered there since 2007, with one published trial — whose abstract is not even indexed.

A pig-brain peptide mixture given by infusion for stroke and dementia in some fifty countries. Cochrane: no effect on death after stroke, more serious adverse events.

The first medicine that builds bone rather than slowing its loss. Approved since 2002 on a trial that cut spinal fractures by two-thirds.

A GnRH analogue that switches the sex-hormone axis off. Forty years as a standard prostate-cancer treatment, and the drug behind most puberty suppression and IVF protocols.

The first amylin drug, approved in the US in 2005 for diabetes. Modest weight loss in trials — and the ancestor of cagrilintide.

A synthetic version of the hormone that switches growth hormone off. Approved since 1988 for acromegaly and hormone-secreting tumours — and it slows those tumours' growth.

A pegylated fragment of a muscle-made IGF-1 variant, sold for repair and growth. Never injected into a human in any study.

A peptide designed to kill the blood vessels that feed fat. Dramatic in obese monkeys, kidney-toxic in the same monkeys, and never reported in a human.

GHK-Cu's less-studied cousin, sold for hair growth. One laboratory study on plucked follicles; no human trial.

A 28-amino-acid gut and nerve hormone. Licensed in a few countries for erectile dysfunction; a 461-person COVID trial found nothing; sold as a nasal spray for 'mould illness' with no trial at all.

An 11-amino-acid fragment of erythropoietin that repairs without raising red cells. A real phase 2 in a rare neuropathy; sold online for everything else.

Cagrilintide and semaglutide in one pen. Two published phase 3 trials: 20.4% weight loss at 68 weeks — less than the company had hoped, more than either drug alone.

Lilly's selective amylin agonist. A published 48-week phase 2 found up to 20% weight loss with fatigue, not nausea, as the signature side effect.

Amgen's once-monthly antibody with two GLP-1 peptides attached. Up to 16% weight loss at 52 weeks in a published phase 2, with a GIP-blocking twist.

A Chinese once-weekly GLP-1 analogue with a published phase 3: 13.2% weight loss at 40 weeks. Approved nowhere outside China's review process.

The second bone-building peptide. An 18-month trial of 2,463 women cut new spinal fractures by more than 80%, with less high calcium than teriparatide.

A 32-amino-acid hormone that was an osteoporosis medicine for thirty years — until a cancer signal and a marginal fracture trial ended most of that use.

A nine-residue vasopressin analogue in use since the 1970s. Cuts night-time urination modestly; causes dangerous low sodium in about one older adult in thirteen. Banned in sport as a masking agent.

A calf-thymus peptide extract registered in Russia since the 1980s. Its longevity claim rests on one St Petersburg series without randomisation or blinding.

A three-amino-acid 'brain bioregulator' from the epitalon school. Cell and rat studies; the human reports are Russian, uncontrolled and unindexed.

The senolytic peptide. One landmark mouse paper in Cell, no human study of any kind, and a grey market that sells it as an anti-ageing injection.

Zealand and Roche's weekly amylin analogue. A published phase 2: 8–10% weight loss at 28 weeks in 493 adults, with nausea in one in five. A second phase 2, in type 2 diabetes, reported 7–9% in October 2026. Phase 3 started in September 2026.

A once-daily GLP-1 medicine with a neutral heart trial and one unexpected result: slower motor decline in early Parkinson's disease, in a 156-person phase 2.

The original peptide medicine, in use since 1922. Included as the reference point: what a century of evidence looks like, and what the sharpest peptide side effect looks like.

The best-selling peptide supplement. Pooled trials show better skin hydration and elasticity — until the trials are sorted by who paid for them, when the effect disappears.

A muscle dipeptide sold as a supplement for ageing and blood sugar. Eight small trials pooled show lower fasting glucose and HbA1c in prediabetes and diabetes.

A two-amino-acid 'thymic bioregulator' from the epitalon school. Mouse lifespan and tumour studies; no human trial.

A Russian brain-extract injection for stroke and cognitive decline, like cerebrolysin. One double-blind trial of 272 patients exists — with no numbers in its abstract.

A six-residue cosmetic peptide sold as a topical alternative to botulinum toxin. One small randomised trial supports it — published three times by the same group.

A palmitoylated five-residue peptide from collagen, and the best-evidenced cosmetic peptide here: one 93-person split-face trial run by its user.

A licensed GnRH agonist used in prostate cancer and precocious puberty — and, on bodybuilding forums, a single injection claimed to restart the testosterone axis on the strength of one case report.

An eight-residue tight-junction regulator for coeliac disease: a phase 2b that met its endpoint at the lowest dose only, and a phase 3 stopped for futility.

A weekly GLP-1/glucagon dual agonist for liver disease. Its phase 2b hit the MASH-resolution endpoint decisively and missed the fibrosis one.

A GLP-2 analogue and the only approved drug that reduces the need for intravenous feeding in short bowel syndrome.

The 29-residue hormone that raises blood sugar, and the emergency treatment for severe hypoglycaemia. Now also a nasal powder.

A 14-residue peptide taken by mouth that is not absorbed: it works entirely on the inside surface of the gut.

The nine-residue hormone behind both blood pressure and urine concentration. Its largest trial in septic shock found no survival benefit.

A 25-residue cone-snail venom peptide delivered into spinal fluid for severe chronic pain — with a psychiatric boxed warning and a trial that was published twice.