What is SS-31?
SS-31: Mitochondria-targeted tetrapeptide (Szeto-Schiller peptide) that binds cardiolipin in the inner mitochondrial membrane, stabilizing electron transport and reducing oxidative stress. The sources cited here most often discuss it for: Mitochondrial function, animal; Muscle strength in Barth syndrome; Exercise tolerance, animal and anecdotal. Evidence label: Approved (specific use).
- Type
- Peptide
- Family
- Longevity & Mitochondria
- Evidence label
- Approved (specific use) (5 of 5)
- Regulatory status
- FDA granted accelerated approval on September 19, 2025 to elamipretide (Forzinity) as the first treatment for Barth syndrome in patients weighing at least 30 kg; continued approval depends on a confirmatory trial.
- Goals discussed
- Energy & Endurance, Longevity & Cellular Aging, Muscle & Tone
- Also called
- Forzinity, elamipretide, Bendavia, MTP-131, Szeto-Schiller peptide, SS31
- Last reviewed
- 2026-10-11
- Mitochondria-targeted tetrapeptide (Szeto-Schiller peptide) that binds cardiolipin in the inner mitochondrial membrane, stabilizing electron transport and reducing oxidative stress; FDA accelerated approval Sept 2025 as Forzinity for muscle strength in Barth syndrome (>=30 kg).12
Regulatory status FDA granted accelerated approval on September 19, 2025 to elamipretide (Forzinity) as the first treatment for Barth syndrome in patients weighing at least 30 kg; continued approval depends on a confirmatory trial. 1
SS-31 represents a new class of compounds that can recharge the cellular powerhouse and restore bioenergetics.
Review by the peptide's co-developer summarizing mostly animal evidence (Br J Pharmacol, 2014).
What is SS-31 researched for?
The three outcomes most discussed for SS-31 in the sources below, as those sources report them. humanpeptides.fyi makes no claims of its own: a listed benefit can be unproven or can have failed in trials, and the label on each line says which.
What do researchers and users say about SS-31?
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.
Phase 3 randomized trial in 218 adults with primary mitochondrial myopathy (Neurology, 2023); a negative result.
I would say that SS-31 is the closest I've come to what feels like the movie Limitless.
Unverified self-report; in the same thread several people with ME/CFS described crashes, fatigue and palpitations.
What side effects of SS-31 are reported?
- Injection-site reactions (redness, itching, lumps, hives) very commonFDA label; Reddit1213
- Users report fatigue, nausea, diarrhea, palpitationsanecdotal8
- Serious hypersensitivity reactions needing emergency care have occurred, including rash, papular lesions, eczema-like dermatitis and cough, starting anywhere from minutes to months after treatment begins.FDA label2
- Raised blood eosinophil counts were common with use of 30 days or more, peaking around 90 days, without linked symptoms.FDA label2
- The approved product contains benzyl alcohol, which is toxic to newborns.FDA label2
- Exposure to its metabolites rises sharply in people with severe kidney impairment.FDA label2
- Headaches, hot flushes and flares of autonomic symptoms were reported by some users with ME/CFS.anecdotal11
What do peptide guides say about SS-31?
- PepEdHub PepEdHub describes SS-31 as concentrating in the inner mitochondrial membrane by binding cardiolipin, stabilizing cristae, reducing reactive oxygen species and preventing cytochrome c release. 14
- Seek Peptides Seek Peptides lists SS-31 for mitochondrial dysfunction, chronic fatigue, neurodegenerative and cardiovascular support and age-related energy decline, calling it a cutting-edge longevity peptide with promising research. 15
- FDA FDA based the Barth approval on improved knee-extensor strength, an intermediate measure it considers reasonably likely to predict benefits such as standing more easily or walking farther. 1
What does the research say, system by system?
How strong is the evidence for SS-31?
FDA accelerated approval for rare disease (Barth); strong animal data; mixed human trials in other conditions; healthy-person use anecdotal
Approved by the FDA (or a major regulator) for at least one specific use. Approval covers that use only, not the other benefits listed. How tiers work
Questions about SS-31
What is SS-31?
Mitochondria-targeted tetrapeptide (Szeto-Schiller peptide) that binds cardiolipin in the inner mitochondrial membrane, stabilizing electron transport and reducing oxidative stress.
Is SS-31 FDA-approved?
FDA granted accelerated approval on September 19, 2025 to elamipretide (Forzinity) as the first treatment for Barth syndrome in patients weighing at least 30 kg; continued approval depends on a confirmatory trial.
What is SS-31 researched for?
The sources cited on this page most often discuss three outcomes: Mitochondrial function, animal; Muscle strength in Barth syndrome; Exercise tolerance, animal and anecdotal. Each line above shows what the source reports and how strong that evidence is.
What side effects of SS-31 are reported?
Reported in the cited sources: Injection-site reactions (redness, itching, lumps, hives) very common; Users report fatigue, nausea, diarrhea, palpitations; Serious hypersensitivity reactions needing emergency care have occurred, including rash, papular lesions, eczema-like dermatitis and cough, starting anywhere from minutes to months after treatment begins. The list is not complete, and few listed risks does not mean a compound is safe.
How strong is the evidence for SS-31?
Evidence label: Approved (specific use). FDA accelerated approval for rare disease (Barth); strong animal data; mixed human trials in other conditions; healthy-person use anecdotal.
What else is SS-31 called?
Names used for it include Forzinity, elamipretide, Bendavia, MTP-131, Szeto-Schiller peptide, SS31.
Does humanpeptides.fyi recommend SS-31?
No. humanpeptides.fyi makes no claims and no recommendations of its own. It summarizes and links to what others have published and posted. Nothing here is medical advice; talk to a licensed clinician.