The idea behind these is a good one. Mitochondria do decline with age, telomeres do shorten, and a compound that slowed either would be a genuinely useful thing to have. Nobody looking into this is being gullible.
What follows is where each of them actually sits, because the four sold under the longevity heading are four completely different kinds of thing.
One has an FDA approval, granted in September 2025, and it is far narrower than the marketing suggests.
One has three decades of research behind it, almost all of it from a single laboratory. Its strongest human data belongs to a different substance than the one you can buy.
The other two are molecules your own mitochondria produce. Both are interesting and both have been studied almost entirely in mice.
None of them has been shown to extend anyone's life, and the last section explains why that is harder to demonstrate than it sounds.
The four compounds, sorted by evidence
| Compound | What it is | Best human evidence | Where it stands |
|---|---|---|---|
| SS-31 (elamipretide) | Four amino acids, binds cardiolipin in mitochondria | Phase 3 trials, mixed and mostly negative | FDA approved for one ultra-rare disease |
| Epitalon | Four amino acids, from a pineal extract | Observational studies of the extract, not the peptide | Not approved anywhere |
| MOTS-c | A peptide your mitochondria encode | Almost none | Not approved anywhere |
| Humanin | The first mitochondrial-derived peptide found | Almost none | Not approved anywhere |
The gap between the first row and the other three is wide, and it is where most of the confusion in this category comes from.
Is SS-31 FDA approved?
SS-31 is the only compound here with regulatory-grade evidence, and the shape of that evidence is not what you would guess.
Elamipretide is a four amino acid peptide. It accumulates in the inner mitochondrial membrane and binds cardiolipin, a lipid that mitochondria need to produce energy efficiently. The mechanism is real and well characterized.
On September 19, 2025 the FDA granted accelerated approval for Barth syndrome, an ultra-rare inherited mitochondrial disorder, in adults and children weighing at least 30 kg. The brand name is Forzinity. It is the first mitochondria-targeted peptide ever approved.[^1]
In TAZPOWER, the placebo-controlled crossover trial in Barth syndrome, neither co-primary endpoint was met. Not the six-minute walk test, not the symptom score. The approval rests on the open-label extension that followed, where eight patients reached 36 weeks and walking distance improved by 95.9 meters. Accelerated approval is conditional, and a confirmatory trial is still required.[^1]
Meanwhile the larger trial in an adjacent condition failed outright. MMPOWER-3 enrolled over 200 patients with primary mitochondrial myopathy across 27 centers in seven countries, and missed both primary endpoints.[^2] The dry macular degeneration program missed its primary endpoints too.
So the summary runs like this. A validated mechanism. One narrow conditional approval, built on an open-label extension in eight people. And a run of well-powered negative trials everywhere else.
That last part is worth sitting with, because the mechanism did not turn out to be wrong. Elamipretide binds cardiolipin, cardiolipin matters, and the compound reached the tissue it was meant to reach. What the trials showed is that fixing one step in a complicated system does not reliably fix the thing you were hoping to fix. That is a disappointing result, and a long way from the idea having been foolish. Whether it does anything for healthy aging has not been tested, and the closest thing to a test, a large trial of exercise capacity in people with mitochondrial disease, was negative.
A note on the state of the internet here. Several sites still say SS-31 is not approved for anything, including two updated within the last few weeks. The approval detail is specific and consistent wherever it is reported, down to the date, the brand name and the weight threshold, so the disagreement is not a genuine dispute about the facts.
Does epitalon lengthen telomeres?
Epitalon is a synthetic four amino acid peptide, Ala-Glu-Asp-Gly, developed from a pineal gland extract by Vladimir Khavinson's group in Russia from the 1980s onward.
The cell work is the strongest part of it. A 2003 study reported that epitalon applied to human fetal fibroblasts switched on hTERT, restored telomerase activity, and let the cells divide past the Hayflick limit by more than ten additional doublings.[^3] For years that finding sat unreplicated outside Khavinson's own institute, which is the weakness people raise first about this evidence base. Independent replication in human cell lines has been reported more recently, which strengthens it.[^4]
The problem will feel familiar if you have read our guide on the healing pair.
The human studies people cite for epitalon were mostly run on epithalamin, the pineal extract, rather than on the synthetic peptide. That includes the long follow-up of elderly patients and the retinal work. Those studies were unblinded and conducted at Russian institutions. The substance in them is also not the substance in the vial.[^4]
The same shape has now appeared three times here. TB-500 is a fragment sold on research belonging to the full protein. N-Acetyl Semax Amidate is a modified molecule sold on trials of the unmodified one. Epitalon is a synthetic peptide sold on observational data from the extract it was derived from. In each case the reasoning is plausible and the substitution has never been tested.
Cell culture telomerase activation is a real finding. It is not evidence that injecting the peptide lengthens telomeres in a person, and no registered trial has tested that.
What are MOTS-c and humanin?
These two belong together because they are the same kind of thing, and that kind of thing is fairly new.
Mitochondria have their own small genome, and in 2001 researchers found it encodes peptides of its own. Humanin was the first. MOTS-c was identified later and is the one that reached the supplement market, largely on mouse work suggesting it improves insulin sensitivity and mimics some effects of exercise.[^5]
The biology is real and the human evidence is close to absent. What exists is measurement studies, meaning people have looked at how much MOTS-c circulates naturally and how that correlates with fitness or age. That is a different thing from giving it to somebody and seeing what happens.
Our guide on why most peptides have no human evidence covers how a compound ends up in this position. For these two the answer is mostly that they are recent, and nobody has funded the trials yet.
One point deserves stating outright. Your body making a compound does not mean injecting it is safe, especially at a dose your body never makes, and insulin is the obvious example of that principle.
What about NAD+, NMN and NR?
They come up constantly in the same conversations, they are sold by the same clinics, often in the same package, and they are not peptides at all.
NAD+ is a coenzyme every cell uses in energy metabolism. Levels decline with age, which is the observation the whole category rests on. Nicotinamide mononucleotide and nicotinamide riboside are precursors, meaning your body converts them into NAD+, and both are sold as oral supplements.
The precursors do raise NAD+ in the blood. That part has been measured in humans and nobody disputes it.
Whether raising it does anything you would notice is a different question, and the human trials so far have been small, short, and mixed. Better numbers on a lab report are a surrogate endpoint of exactly the kind described below.
They are included only because the category bundles them together, and leaving them out would look like an oversight. The chemistry is different, the route is different, and they deserve their own page rather than a paragraph.
Why no peptide has been shown to extend lifespan
There is a structural reason none of these has evidence for what it is sold for, and it has little to do with whether the compounds work.
To show that something extends human lifespan you would need to give it to a large number of people and wait for decades, with a control group doing the same. Nobody funds that, no company can wait for it, and the participants would outlast the patents.
So every trial in this space uses a stand-in: a biomarker, a walking distance, a measure of grip strength, a scan. Those are reasonable proxies for something nobody can measure directly. A compound can move a marker in the right direction and change nothing about how long or how well you live, which is the same distinction our guide on the growth hormone peptides makes about lean mass and function.
That is worth holding onto when you read a longevity claim. It does not make the compounds worthless. It means the evidence in this category will never look like the evidence for the GLP-1 drugs, and anybody promising you otherwise is selling something.
How do I know if it is working?
Most of this page speaks to somebody deciding. Plenty of readers are past that, and the honest position for them is a bit awkward.
There is no test that tells you whether a longevity compound is working. That is not an oversight, it follows from everything above: the endpoint is decades away and the surrogate markers are stand-ins nobody has validated for this purpose. Routine bloodwork is worth having for general reasons, and none of it answers this particular question.
The cost side deserves the same plainness. These are taken indefinitely by design, not for a defined course, and epitalon protocols in particular run in cycles across years. A monthly figure that looks manageable becomes a large number over a decade, and our guide on what peptide therapy costs does that arithmetic. Somewhere in an open-ended commitment there should be a moment where you decide whether to keep going, and with no marker to check, that decision is going to be made on grounds other than evidence. Better to know that in advance.
What the four have in common
They are all injected, apart from the oral epitalon preparations, which have their own absorption question.
None is approved for aging, anywhere, including SS-31.
None has published dosing derived from a human dose-finding study, so the protocols in circulation come from somewhere other than research.
And all four are sold on mechanism. Cardiolipin binding, telomerase activation, mitochondrial signaling. Each mechanism is real. A real mechanism is a reason to run a trial rather than the result of one.
Should you stack longevity peptides?
These are sold in combinations more often than alone. Epitalon with MOTS-c, SS-31 with something else, a longevity blend in a single vial.
A stack multiplies the unknowns instead of averaging them. Two compounds with no human dosing data give you two compounds with no human dosing data, plus an interaction nobody has looked at, plus no way to attribute any effect or any problem to either one.
Our guide on mixing peptides covers why combining them in one syringe is a separate question again. Our guide on spotting a wrong dose calculation covers what a blend does to the arithmetic, since whoever made it chose the ratio.
If you are going to run more than one, running them one at a time is the only version where you learn anything.
Where this stops being useful
Whether any of these will help you, which nobody can answer for any of them.
What dose to use, which no human study establishes for three of the four.
Whether the SS-31 approval will hold. Accelerated approval requires a confirmatory trial, and those sometimes fail, which would change the answer here.
Common questions
Is SS-31 FDA approved?
Yes, narrowly. Accelerated approval was granted on September 19, 2025 for Barth syndrome, an ultra-rare inherited disorder. It covers patients weighing at least 30 kg and is sold as Forzinity. It is not approved for aging, mitochondrial myopathy or anything else, and several websites still say it has no approval at all.
Does SS-31 work for anti-aging?
Nobody has tested it. The closest thing was a phase 3 trial of exercise capacity in mitochondrial disease, which missed both primary endpoints.
Does epitalon lengthen telomeres?
In cultured human cells, the published work says it activates telomerase and extends telomeres. Whether injecting it does that in a person has not been tested in any registered trial.
Why is epitalon's evidence controversial?
Almost all of it comes from one research group, and the human studies people cite used epithalamin, the pineal extract, rather than the synthetic peptide sold today. Those studies were also unblinded.
Does MOTS-c work like exercise?
That claim comes from mouse studies. Human work so far has mostly measured how much MOTS-c people have naturally, which is a different question from what happens when you inject it.
Are these safe?
For SS-31 there is trial safety data, and injection site reactions are very common. For the other three, safety has not been characterized in humans at the doses being used.
Which one has the best evidence?
SS-31, by a wide margin, though its evidence covers one rare genetic disease and says nothing about aging, which is a distinction doing most of the work here.
Are NAD+, NMN and NR peptides?
No. NAD+ is a coenzyme and the other two are precursors your body converts into it. They are sold alongside these compounds and they are a different kind of thing entirely, taken orally rather than injected.
How do I know if a longevity peptide is working?
You cannot. The endpoint is decades away and no surrogate marker has been validated for this purpose. Anybody offering a test that settles it is selling the test.
Should I stack them?
A stack gives you the unknowns of each compound plus an interaction nobody has studied, and no way to attribute an effect to any of them. Running one at a time is the only version where you learn anything.
Do any of them extend lifespan?
Not demonstrably, in people. No trial of that kind has been run for any of them, and there is a structural reason why: it would take decades and nobody funds it.
Sources
[^1]: FDA accelerated approval of elamipretide (Forzinity) for Barth syndrome, September 19, 2025, and the TAZPOWER trial program. Approval covers adults and children weighing at least 30 kg. In the placebo-controlled crossover phase neither co-primary endpoint was met, being the six-minute walk test and the Barth Syndrome Symptom Assessment. The approval rests on the open-label extension, in which eight patients reached 36 weeks and six-minute walk distance improved by 95.9 meters, p=0.024. Accelerated approval carries a confirmatory trial obligation.
[^2]: MMPOWER-3 trial of elamipretide in primary mitochondrial myopathy. Phase 3 randomized controlled trial, roughly 218 to 231 participants across 27 centers in seven countries. Failed both primary endpoints, being the six-minute walk test and the PMMSA total fatigue score.
[^3]: Khavinson VKh, Bondarev IE, Butyugov AA. Peptide promotes overcoming of the division limit in human somatic cells. Bulletin of Experimental Biology and Medicine, 2003. Cell culture study. Epitalon applied to human fetal fibroblast cultures induced hTERT expression, increased telomerase activity by TRAP assay, and extended proliferative lifespan beyond approximately 50 population doublings. Single laboratory, cell culture only.
[^4]: Independent replication of the epitalon telomerase findings, and the distinction between epitalon and epithalamin. A 2025 study in Biogerontology is described as the first independent Western replication of telomere elongation in normal human cell lines. Separately, the strongest human longevity data attributed to epitalon comes from studies of epithalamin, the pineal extract from which the synthetic peptide was derived, and those studies were unblinded and conducted at Russian institutions.
[^5]: Mitochondrial-derived peptides. Humanin was the first identified, in 2001. MOTS-c work is predominantly preclinical, with human studies largely measuring endogenous circulating concentrations and their association with fitness and age rather than administering the peptide.