Basics & safetyHuman study
Who should not use peptides: the screening list
Active cancer, pregnancy and a known allergy rule peptides out. Several other conditions need a specialist first. Here is the list, and where each item comes from.
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Research
Every article is tagged by the strength of its evidence, so you can see at a glance what has actually been tested in people.
Basics & safetyMeta-analysis
Research use only: what the label means in the UK and US
“Research use only” is a seller’s statement, not a legal category. In both countries regulators look at how a product is sold and used, and a disclaimer doesn’t settle that.
RecoveryHuman study
BPC-157: what the evidence in people actually shows
A big rat literature, three tiny uncontrolled human reports and one long-silent colitis trial. Here is exactly what has been tested in people.
MetabolicHuman RCT
Retatrutide: what the trials show so far, and what is still a press release
Peer-reviewed trials show 24% weight loss at 48 weeks and large falls in liver fat; the headline 28% phase 3 figure is still company-reported.
LongevityHuman RCT
Nicotinamide riboside raised NAD+ by about 60% in older adults. Nothing else clearly changed
In a six-week crossover trial of 24 healthy people aged 55 to 79, NR lifted NAD+ in blood cells and was well tolerated. Blood pressure hints were exploratory.
HormonesHuman study
Follistatin-344: the human trials used gene therapy, not an injected peptide
Every human study of follistatin-344 delivered the gene by viral vector into muscle, in a handful of patients. The protein sold in vials has no human data behind it.
CognitivePreclinical
Cortagen: why there is so little to say about it
Cortagen is a four-amino-acid peptide from a Russian research programme. Its published evidence is a few small rat and mouse studies, and there are no human trials.
SkinHuman RCT
Melanotan I and II: one became a licensed drug, the other a mole-changing tanning jab
Melanotan I, as afamelanotide, is approved for a rare light-sensitivity disease. Melanotan II was never approved, and case reports link it to changing moles and melanoma.
Basics & safetyMeta-analysis
Why most peptide evidence is in animals, and how to read it
Only about 5% of treatments tested in animals end up approved for people. Here is why rodent results mislead, and a quick way to read any peptide abstract.
Basics & safetyMeta-analysis
How to read a peptide certificate of analysis
A certificate of analysis answers four separate questions: what is in the vial, how much, how clean, and how safe to inject. Most only answer one or two.
RecoveryPreclinical
BPC-157 and TB-500 together: is there any evidence for combining them?
One rat study has tested the pair head to head, and the combination did no better than either peptide alone. There are no controlled human data.
RecoveryHuman study
What the first human BPC-157 safety study actually found
Two adults got intravenous BPC-157 on two consecutive days and had no side effects or blood-test changes. That’s all a two-person pilot can tell you.
MetabolicPreclinical
MOTS-c: a real discovery, but no human trial yet
The body makes MOTS-c and exercise raises it; injected into mice it improved insulin sensitivity and fitness. No study has yet given it to people and published the results.
ImmunePreclinical
Thymulin: a real thymus hormone with almost no treatment trials in people
Thymulin has been measured in human blood since the 1970s and tracks zinc status and thymus function. Giving it as a treatment has barely been studied in humans.
HormonesPreclinical
IGF-1 LR3: a laboratory reagent with no published human studies
IGF-1 LR3 was built in 1992 to make cells grow faster in culture. Nobody has published a trial of it in people, and the approved version of IGF-1 carries a low blood sugar warning.
SkinHuman RCT
OS-01: what the company-run skin trials show, and what they don't
Three small 12-week studies of the topical peptide OS-01 report better skin barrier and hydration. All were funded and authored by the company that owns it.
HormonesHuman RCT
PT-141 (bremelanotide): what the RECONNECT trials found, and what they didn’t
Bremelanotide is FDA-approved for low sexual desire in premenopausal women. In phase 3 it raised desire scores modestly, didn’t increase satisfying sexual events, and caused nausea in 40%.
Basics & safetyMeta-analysis
The FDA’s July 2026 peptide vote, explained
An FDA advisory committee backed six of seven peptides for US pharmacy compounding, against its own scientists’ advice. The vote is not binding, and nothing is legal to compound yet.
RecoveryHuman RCT
TB-500 and thymosin beta-4: what has actually been tested in people
The human trials used the full thymosin beta-4 protein, mostly as eye drops. TB-500, the seven-amino-acid fragment people inject, has no published human data at all.
RecoveryHuman RCT
Thymosin beta-4 eye drops for dry eye: the 72-person trial missed its main goals
Neither primary outcome improved in the larger of two published phase 2 trials. Some secondary measures did, and the drops looked safe for 28 days.
HormonesHuman RCT
Kisspeptin: what the IVF and brain studies in people actually found
Kisspeptin is one of the better-studied peptides in humans, mostly by one London group. It can trigger egg maturation in IVF, but it is still experimental and unapproved.
LongevityPreclinical
FOXO4-DRI: a clever senolytic that has never been tested in people
FOXO4-DRI clears senescent cells in mice and in dishes of human cells. No human trial has been registered or published, so its effects and safety in people are unknown.
MetabolicPreclinical
5-Amino-1MQ: not a peptide, and so far only tested in mice
A small molecule that blocks the enzyme NNMT cut fat in obese mice and strengthened old mouse muscle, but nobody has published a single study in humans.
RecoveryPreclinical
B7-33: an anti-scarring relaxin fragment that has only been tested in rodents
B7-33 reduces heart and lung scarring in mice and rats. It has never been given to a person, and its parent hormone failed in large human trials.
HormonesHuman RCT
Oxytocin: a proven labour drug, and a nasal spray that hasn’t lived up to the hype
Injected oxytocin reliably prevents bleeding after birth. The intranasal ‘trust hormone’ findings have failed to replicate, and the largest autism trial found no benefit.
MetabolicHuman RCT
Tesamorelin in HIV: the trial that showed it trims deep belly fat, and what it cost
Six months of daily tesamorelin cut visceral fat by 15.2% while placebo users gained 5.0%. Nearly half of users developed antibodies to the drug.
HormonesHuman study
Sermorelin and gonadorelin: the older hormone-releasing peptides
Both were once FDA-approved medicines, and both are now discontinued in the US. Their real track records are narrower, and more medical, than their current reputations.
LongevityHuman RCT
Glutathione: oral, IV and topical, and what each has been shown to do
Daily oral glutathione can raise body stores modestly. Skin-lightening effects are small, short-lived and based on a few trials, while IV glutathione has little evidence and a live contamination problem.
SkinHuman RCT
GHK-Cu: what the skin studies show, and why injections are a different question
A copper peptide with decades of lab work and a few small human trials on skin and ulcers. Nobody has published a trial of injecting it.
Basics & safetyPreclinical
PNC-27: a cancer peptide that has never been tested in patients
PNC-27 kills cancer cells in dishes and in some mouse experiments. No human trial exists, and online claims that it treats cancer have no clinical support.
MetabolicHuman study
AOD-9604: safe in trials, but the weight loss never showed up
Rodent studies were promising and six human trials found it well tolerated, but the largest trial failed on weight loss and development for obesity stopped in 2007.
CognitiveMeta-analysis
Cerebrolysin: what the stroke and dementia trials show once you add them up
Manufacturer-backed trials and pooled analyses report benefits; independent Cochrane reviews find no effect on stroke deaths and only very low-certainty gains in dementia.
MetabolicHuman RCT
Retatrutide’s phase 2 trial: 24% weight loss at 48 weeks, in 338 people
The top dose took off 24.2% of body weight against 2.1% on placebo. It’s a striking number from a mid-sized, US-only trial with a generous way of counting.
HormonesHuman RCT
Tesamorelin: the one GHRH drug with phase 3 evidence, and what it does and doesn’t show
In two phase 3 trials of 806 people with HIV, tesamorelin cut deep belly fat by about 15% more than placebo. The fat came back when it stopped, and nobody has run the trials people now cite it for.
LongevityHuman RCT
SS-31 (elamipretide): what a decade of human trials found
Elamipretide is now an FDA-approved drug for one ultra-rare disease, on the strength of 12 patients. Its large trials in commoner conditions mostly missed their main goals.
ImmuneHuman RCT
LL-37: the body’s own antimicrobial peptide, and why the wound trials disappointed
LL-37 is central to innate immunity, but as a drug the evidence is thin: one small leg-ulcer trial looked good, and the larger follow-up failed.
MetabolicHuman RCT
Cagrilintide and CagriSema: what the amylin trials found
Alone, cagrilintide cut weight by about 11% in 26 weeks; paired with semaglutide it reached 20% at 68 weeks, but lost a head-to-head against tirzepatide.
ImmuneHuman RCT
ARA-290 (cibinetide): what the small nerve-repair trials found
Three small phase 2 trials suggest it can regrow damaged small nerve fibres; the pain results are weaker, and there has never been a phase 3 trial.
MetabolicHuman RCT
SELECT: semaglutide cut major heart events by 20% in people who already had heart disease
In 17,604 adults with obesity and existing cardiovascular disease but no diabetes, semaglutide lowered major cardiac events from 8.0% to 6.5% over about three years.
SleepHuman RCT
DSIP: why the ‘sleep peptide’ never became a sleep drug
Swiss trials in the 1980s reported better sleep with DSIP; the two independent placebo-controlled trials found little of clinical value. Nobody has found its gene or receptor.
Basics & safetyHuman RCT
Injected, oral or nasal: does the route matter for peptides?
Yes, a lot. Most peptides are destroyed or blocked in the gut, which is why nearly all peptide drugs are injected. Oral semaglutide is the exception, and it needed special engineering.
LongevityHuman RCT
NAD+, NMN and NR: what the human trials actually show
Oral NR and NMN reliably raise NAD+ in blood. Whether that makes anyone healthier is far less clear, and IV NAD+ drips have almost no trial evidence at all.
HormonesHuman study
Ipamorelin: one dosing study, one failed surgical trial, and no human data on the popular blend
Ipamorelin reliably releases growth hormone, but its human record is a 1999 dosing study and a 2014 trial that missed its goal. No one has published a human study of it combined with CJC-1295.
ImmunePreclinical
KPV: a promising gut anti-inflammatory that has never been tested in people
A three-amino-acid fragment of alpha-MSH calms colitis in mice and inflammation in cultured human cells. No human trial has been published.
MetabolicHuman RCT
SURMOUNT-1: how much weight tirzepatide took off in 72 weeks
At the top dose, people lost 20.9% of their body weight against 3.1% on placebo. Here is who was in the trial, what it cost them in side effects, and what it can’t tell you.
MetabolicHuman RCT
Tirzepatide: what SURMOUNT and SURPASS found
Around 20% average weight loss at 72 weeks, a head-to-head win over semaglutide, and heart-outcome data that matched rather than beat an older GLP-1 drug.
CognitiveHuman study
Semax: what the stroke studies found, and which ACTH fragment it really is
Semax is ACTH(4-7) with a Pro-Gly-Pro tail, which is why papers also call it an ACTH(4-10) analogue. Its human evidence is a few small, unblinded Russian stroke studies.
ImmuneHuman RCT
Thymosin alpha-1: what decades of human trials actually show
A licensed drug in some countries with thousands of trial patients behind it, but its biggest modern trials in sepsis and hepatitis C found no benefit.
ImmuneHuman RCT
Larazotide: what happened to the coeliac drug that reached Phase 3
Five controlled coeliac trials, one small positive signal at the lowest dose, and a Phase 3 stopped in 2022 because it wasn't going to work.
LongevityHuman study
Epitalon: what the human evidence actually is, and who produced it
The human data on epitalon come from one research network, and they tested a pineal extract rather than the synthetic peptide itself. Independent work so far is limited to cells.
HormonesHuman study
CJC-1295: what two small 2006 studies showed, and why nothing followed
One version of CJC-1295 raised growth hormone for about a week in healthy adults. The other, sold as “no DAC”, has never been tested in people at all.
MetabolicHuman RCT
STEP 1: what the semaglutide 2.4 mg obesity trial actually found
Weekly semaglutide cut body weight by 14.9% over 68 weeks against 2.4% on placebo. Most of that came back within a year of stopping.
MetabolicHuman RCT
Semaglutide: what the big trials actually showed
About 15% weight loss at 68 weeks, fewer heart attacks and slower kidney decline in large trials, with stomach side effects, gallbladder risk and weight regain on stopping.
CognitiveHuman study
Selank: what the anxiety trials actually tested, and where
Selank’s human evidence is a handful of small Russian studies without placebo groups, most from the team that made it. Promising on paper, unproven by any independent standard.
Basics & safetyMeta-analysis
How to read a peptide study in five minutes
Seven questions that sort a real finding from a weak one: who was studied, how many, compared with what, measured how, for how long, and who paid.