--- title: "SS-31: what sources report" url: https://humanpeptides.fyi/peptides/ss-31 site: humanpeptides.fyi last_reviewed: 2026-10-11 --- # SS-31 > humanpeptides.fyi makes no claims of its own. Every statement below reports what a cited source says, with its link. Not medical advice. 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). ## At a glance - **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 ## 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; FDA accelerated approval Sept 2025 as Forzinity for muscle strength in Barth syndrome (>=30 kg). Sources: , **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. Source: ## What is SS-31 researched for? ### 1. Mitochondrial function, animal - Improves mitochondrial function: restored ATP production and OXPHOS coupling and reversed redox stress in aged mouse muscle (animal studies) Sources: , - Goals: [Energy & Endurance](https://humanpeptides.fyi/objectives/energy), [Longevity & Cellular Aging](https://humanpeptides.fyi/objectives/longevity) ### 2. Muscle strength in Barth syndrome - Improves knee-extensor muscle strength in Barth syndrome (basis of FDA accelerated approval; confirmatory trial required) Sources: , - Goals: [Muscle & Tone](https://humanpeptides.fyi/objectives/muscle) ### 3. Exercise tolerance, animal and anecdotal - Improved exercise tolerance/endurance and fatigue resistance in aged mice (animal) Sources: , - Users report more energy, clarity and workout performance; many report nothing (anecdotal Reddit) Sources: - Goals: [Energy & Endurance](https://humanpeptides.fyi/objectives/energy) ## What do researchers and users say about SS-31? > "SS-31 represents a new class of compounds that can recharge the cellular powerhouse and restore bioenergetics." > > Szeto HH, First-in-class cardiolipin-protective compound as a therapeutic agent to restore mitochondrial bioenergetics. Context: Review by the peptide's co-developer summarizing mostly animal evidence (Br J Pharmacol, 2014). > "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." > > Karaa A, et al., Efficacy and Safety of Elamipretide in Individuals With Primary Mitochondrial Myopathy: The MMPOWER-3 Randomized Clinical Trial. Context: 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." > > Anonymous user, r/cfs, SS-31: your experiences? I'll share mine (just started). Context: 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 common (FDA label; Reddit) Sources: , - Users report fatigue, nausea, diarrhea, palpitations (anecdotal) Sources: - 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 label) Sources: - Raised blood eosinophil counts were common with use of 30 days or more, peaking around 90 days, without linked symptoms. (FDA label) Sources: - The approved product contains benzyl alcohol, which is toxic to newborns. (FDA label) Sources: - Exposure to its metabolites rises sharply in people with severe kidney impairment. (FDA label) Sources: - Headaches, hot flushes and flares of autonomic symptoms were reported by some users with ME/CFS. (anecdotal) Sources: ## 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. - **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. - **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. ## What does the research say, system by system? ### Body & tissues - Skeletal muscle: increased gastrocnemius mass and fatigue resistance in aged mice (animal) Sources: - Muscle strength in Barth syndrome (human, accelerated approval) Sources: ### Cells & mitochondria - Binds cardiolipin, improves inner-membrane structure, electron transport and ATP output, lowers ROS (FDA label, animal) Sources: , - Did not increase mitochondrial content, i.e., improved quality not quantity (animal) Sources: ### Brain, mood & sleep - Some users report mental clarity; others insomnia (anecdotal Reddit) Sources: ### Muscle - Improved muscle performance in aged mice within 8 days (animal) Sources: - Phase 3 MMPOWER-3 in primary mitochondrial myopathy failed primary endpoints (6-min walk, fatigue) at 24 weeks (human RCT) Sources: , ### Also notable - Being explored by chronic fatigue (ME/CFS) community; mixed self-reports (anecdotal) Sources: ## How strong is the evidence for SS-31? **Approved (specific use)** (5 of 5). 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._ ## 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. --- Family: [Longevity & Mitochondria](https://humanpeptides.fyi/peptides?cat=longevity). HTML version: . Disclaimer: