Question 1

What is SS-31?

Accepted Answer

SS-31 is a research compound of four amino acids. It aims at one target inside the cell: a fat called cardiolipin, which sits in the inner membrane of the mitochondria. Mitochondria are the parts of a cell that turn food and oxygen into usable energy, and cardiolipin is part of their internal structure. A 2018 review describes the family it belongs to as peptides that selectively target cardiolipin and increase coupling efficiency. Coupling efficiency means how much energy a mitochondrion gets out of the fuel it burns. It has to be injected. A 2023 mouse study notes that elamipretide is a short tetrameric peptide that is not orally bioavailable. The human trials gave it under the skin, once a day.

Question 2

Is SS-31 the same as elamipretide?

Accepted Answer

Yes, and the two names matter more here than on most pages, because they lead to different literatures. A 2026 review of peptides lists the compound as SS-31 (elamipretide). A 2022 mouse study spells it out as Elamipretide (Elam, a.k.a. SS-31), and a 2025 skin study adds a third name, calling it the antioxidant peptide SS31 (also known as MTP-131, elamipretide). The practical point is this. Searching for SS-31 mostly returns laboratory work and vendor copy. Searching for elamipretide returns the randomised trials, the regulatory record and the failures. Anybody reading only the first name is reading only half the evidence, and it is the more flattering half.

Question 3

Is SS-31 FDA approved?

Accepted Answer

Yes, for one rare inherited disease, and for nothing else. That sentence is unusual on this site and it needs both halves. A 2026 review of the peptides approved that year records that in 2025, elamipretide further expanded this paradigm by becoming the first disease-specific treatment approved for Barth syndrome. The clinical reference text is more specific still: elamipretide is indicated for the improvement of muscle strength in individuals with Barth syndrome. Barth syndrome is rare and inherited. The same reference describes it as a multisystem disorder characterized in affected males by cardiomyopathy, neutropenia, skeletal myopathy, and prepubertal growth delay, diagnosed through a genetic variant or a laboratory ratio of two fats. So the approval is narrow in three directions at once: one named disease, one named outcome, and one group of patients identified by their genes. It is not an approval for fatigue, for performance, for ageing or for heart failure, and the existence of an approval for one of those things is often read as evidence for all of them.

Question 4

Does SS-31 actually work?

Accepted Answer

It depends entirely on which question is being asked, and the honest answer runs in both directions. In Barth syndrome, yes, by the standard a regulator accepted. TAZPOWER was a 28-week randomized, double-blind, and placebo-controlled trial followed by a 168-week open-label extension. Ten patients entered the extension and eight reached the week 168 visit, and significant improvements from OLE baseline on 6MWT occurred at all OLE time points, amounting to a cumulative 96.1 m of improvement. The 6MWT is the six-minute walk test, a measure of how far somebody can walk in six minutes. In the larger disease, no. MMPOWER-3 randomised 218 people with primary mitochondrial myopathy, and the study did not meet its primary endpoints assessing changes in the 6MWT and PMMSA total fatigue score. The trial authors put it in the strongest available language: this study provides Class I evidence that elamipretide does not improve the 6MWT or fatigue at 24 weeks compared with placebo in patients with primary mitochondrial myopathy. Read those two together. Eight people followed for three years in a rare genetic disease, and 218 people in a properly powered randomised trial that missed. Both results are real, and they are answers to different questions.

Question 5

What does SS-31 peptide do?

Accepted Answer

Everything below was measured in animals or in cells. That is worth holding onto while reading it. A 2018 review of this peptide family reports that in ageing animals the compounds rejuvenate mitochondrial bioenergetics and remodel mitochondrial cristae structure. Cristae are the folds inside a mitochondrion where energy is made, and they flatten with age. The same review credits the family with restoring organ function during aging in the animals studied. A 2022 review adds the heart work. In animal studies, elamipretide has been shown to increase left ventricular ejection fraction in dog models of heart failure with reduced ejection fraction. It also prevented left ventricular remodeling in rats. Ejection fraction is the share of blood the heart pushes out with each beat. In a 2025 mouse study of lung scarring, SS-31 could reduce reactive oxygen species and myeloperoxidase in the treated animals. None of these outcomes has a published equivalent in a healthy person.

Question 6

What conditions has SS-31 been studied in?

Accepted Answer

The list is longer than most readers expect, and every item on it is a disease rather than an enhancement. Two have reached large randomised trials: Barth syndrome and primary mitochondrial myopathy. A third is acute heart attack. In a small early study, 10 of the patients received the mitochondria-targeting peptide elamipretide, in a phase 2a study called EMBRACE. The public registry adds the rest. One is a Phase 2 study of the cardiac and renal effects in patients hospitalized with congestion due to heart failure. Another tested an ophthalmic solution for treatment of Leber's hereditary optic neuropathy, an inherited cause of sudden sight loss. A third is a Phase 3 study in subjects with dry age-related macular degeneration, listed as ACTIVE_NOT_RECRUITING. What the list lacks is a completed study in a healthy person. Everyone enrolled so far had failing mitochondria, a failing heart or a damaged eye. That is a different starting point from somebody who simply wants more energy.

Question 7

Has SS-31 been tested in people?

Accepted Answer

Extensively, and the record is more complete than for almost any other compound on this site. The largest trial is MMPOWER-3, in which eligible participants were randomized 1:1 to receive either 24 weeks of elamipretide at a dose of 40 mg/d or placebo subcutaneously. There were 218 of them, and its registry entry is listed as TERMINATED. The longest is TAZPOWER, which ran 28 weeks blinded and then 168 weeks open-label in Barth syndrome, with ten patients entering the extension. Open-label means everybody knew what they were getting, which matters a great deal for a walking test. The smallest is EMBRACE, where peripheral blood was obtained from patients (n=19) with first-time acute anterior STEMI, and ten of them received the peptide. Beyond those, a Phase 3 trial in dry macular degeneration is still running, and a Phase 2 study of healthy aging and physical function with elamipretide is listed as RECRUITING with no results.

Question 8

Can SS-31 undo aging?

Accepted Answer

No study among the research behind this page has measured anything about ageing in a person given SS-31. The animal work behind that claim is real, though, and it is worth seeing precisely. A 2022 study gave mice 3 mg/kg of Elam or saline subcutaneously 5 days per week for 10 months, starting at 18 months of age. In those mice, Elam improved the physical performance of males but not females, while in females Elam improved cognitive performance and enhanced the maintenance of body weight and fat mass. The authors conclude that Elam enhanced healthy aging and cardiac function in both male and female mice, although the specific effects on function differed between sexes. A 2023 study tested a lighter schedule. Intermittent treatment with elamipretide for 8 months preserved exercise tolerance and left ventricular mass in mice, with modest protection of diastolic function and skeletal muscle force production, but did not affect kidney function. Read what those are. Old mice, treated for most of a year, measured on treadmills and echocardiograms, with results that differ by sex. A mouse that ages better on a compound and a person who wants to feel younger are different questions. The human version is only now being asked: a Phase 2 study of healthy aging is recruiting and has reported nothing.

Question 9

Can SS-31 help with weight loss?

Accepted Answer

No study among the research behind this page has measured body weight or body fat in a person given SS-31, and the nearest animal finding points the other way. In the 10-month mouse study, the reported effect in females was that Elam enhanced the maintenance of body weight and fat mass. Those were old mice, which tend to lose weight and muscle as they age, so holding weight steady counts as a good outcome there. It is the opposite of what somebody asking this question usually wants. The one metabolic result worth knowing comes from a 2026 study in aged female C57BL/6 mice fed a high-fat, high-fructose diet for 16 weeks. Compared with untreated animals, those given SS-31 at 3 mg/kg/day showed marked reductions in hepatic steatosis on histology, which is fat inside the liver rather than fat on the body. Liver fat and body fat are different questions, and the second has not been asked. A 2024 editorial on this class of compounds notes that no studies have evaluated their hypoglycemic effects in diabetic patients, which is how thin the human metabolic record is.

Question 10

How long does it take for SS-31 to work?

Accepted Answer

No trial among the research behind this page reports a week-by-week onset, because none of them looked before six months. The shortest human readout on record is 24 weeks, which is when MMPOWER-3 measured its primary endpoints, and at that point the difference in the least squares mean from baseline to week 24 on distance walked on the 6MWT was -3.2 meters, favouring neither group. The clearest positive human result took far longer. In Barth syndrome, significant improvements from OLE baseline on 6MWT occurred at all OLE time points, accumulating to 96.1 m of improvement by week 168, which is more than three years of continuous use. The animal studies run on the same scale: 10 months of injections in one mouse experiment, 8 months in another. So the published answer to how quickly it works is that no study among the research behind this page has measured a short interval at all, and the only clearly positive human finding emerged over years rather than weeks.

Question 11

Who did SS-31 appear to help in the failed trial?

Accepted Answer

The negative Phase 3 was taken apart afterwards by genotype, and the result is the most interesting piece of this literature. A 2024 post hoc analysis reports that the prespecified subgroup of subjects with disease-causing nuclear DNA pathogenic variants receiving elamipretide experienced an improvement in the six-minute walk test, while the cohort of subjects with mitochondrial DNA pathogenic variants showed no difference versus placebo. Within that first group, a narrower cohort showed an improvement on the 6MWT, trending towards significant, at 25.2 metres against 2.0 metres for placebo, with a p value of 0.06. One slice went further. Subjects with replisome variants who also had chronic progressive external ophthalmoplegia, a condition affecting the muscles that move the eye, showed a significant change at 37.3 metres against -8.0 metres for the placebo group. Now the caution, which the authors share. These are subgroups pulled from a trial that failed overall, and a finding like that is a hypothesis rather than a result. The authors say so by their actions: these data serve as the foundation for a follow-up Phase 3 clinical trial, which is what you do with a hypothesis, not with an answer.

Question 12

What are the potential side effects of SS-31 peptide?

Accepted Answer

What is on record comes from trials in people who were ill, and it is more than this site usually has. In the Barth syndrome extension, injection-site reactions were the most common adverse events across 168 weeks in a small group. In MMPOWER-3, across 218 participants over 24 weeks, most adverse events were mild to moderate in severity. A 2022 review of the compound adds that in early-phase clinical trials, elamipretide administration has not resulted in any severe adverse events. Those are real observations and they have real limits. Every one of them was collected in patients with a diagnosed mitochondrial disease, under supervision, for a defined period, and the same review states plainly that additional studies are necessary to describe the long-term safety and efficacy of elamipretide. Nothing in that record describes a healthy adult using it over years, because no such study has been published. The organ-by-organ questions, who was excluded from the trials, and what interacts with it are taken separately on the safety page.

Question 13

How does SS-31 work?

Accepted Answer

The target is unusually well defined for a compound in this category, and that is exactly what makes the trial record instructive. A 2022 review says elamipretide works by targeting and stabilizing the cardiolipin-cytochrome c supercomplex. Cytochrome c is one of the proteins in the chain that makes cellular energy, and cardiolipin is the fat that holds that chain in place. The stated aim is to maintain cellular biogenetics and prevent reactive oxygen species-induced cell damage. A 2018 review explains why that target was picked. Cardiolipin is important for cristae curvatures and is necessary for optimal activity of the respiratory complexes, cristae being the folds inside a mitochondrion. And ageing is associated with loss of mitochondrial cristae membranes and inhibition of ATP production, ATP being the molecule a cell spends as energy. There is even a marker to measure. A 2026 review calls a ratio of two forms of cardiolipin a rare lipid biomarker with direct interpretability for diagnosis, stratification and target engagement. And that is the lesson here. The same review notes that mitochondrial therapeutics have repeatedly fallen short of disease modification. Hitting the target is not the same as helping the patient, and SS-31 is among the clearest demonstrations of that gap in the whole field.

SS-31