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SS-31 (Elamipretide)4 residuesRYKFEach bubble = one amino acid. Size = residue mass. Color = chemical class.Also known as: SS-31, MTP-131, Bendavia
FDA accelerated approval came through September 2025, making elamipretide one of only a handful of mitochondrial-targeted drugs to reach the market. SS-31 (brand name FORZINITY, also known as elamipretide, MTP-131, or Bendavia) is a four-amino-acid peptide that crosses into mitochondria and binds cardiolipin, a lipid that holds the electron transport chain together. The TAZPOWER trial earned approval based on knee extensor strength gains in Barth syndrome patients, though the randomized-phase primary endpoints were not met. Longevity researchers and biohackers now use SS-31 at community-derived doses between 2 and 10 mg daily for energy, recovery, and mitochondrial support.
Four amino acids. That is all SS-31 is. D-Arg-dimethylTyr-Lys-Phe-NH2, a tetrapeptide small enough to cross cell membranes without relying on mitochondrial membrane potential. It concentrates more than 1,000-fold inside mitochondria and locks onto cardiolipin, the phospholipid that anchors cytochrome c to the inner mitochondrial membrane. SS-31 (elamipretide, CAS 736992-21-5, also called MTP-131 and Bendavia) earned FDA accelerated approval in September 2025 under the brand name FORZINITY (NDA 215244) for Barth syndrome in patients weighing at least 30 kg. The approval rested on open-label extension data from the TAZPOWER trial (n=12)[1], where knee extensor strength improved 42% from baseline at 168 weeks. The randomized-phase primary endpoints, 6-minute walk test and total fatigue score, were not met in the initial 12-week crossover. Mechanistic evidence is strong. Cardiolipin oxidation collapses cristae, slows electron transfer between complexes III and IV, leaks electrons into superoxide, and drops ATP output. SS-31 prevents that peroxidation; it stabilizes cristae architecture and restores electron flow at the source rather than scavenging free radicals after they form. Preclinical models show reversed age-related cardiac dysfunction [2], improved renal filtration, and neuroprotection from ischemia-reperfusion injury. The longevity community has adopted SS-31 at doses between 2 and 10 mg daily, well below the 40 mg FDA-approved dose. No dose-finding trial exists in healthy adults, so these community doses are pragmatic cost and tolerability decisions rather than clinically validated thresholds. Reports from roughly 50 to 100 threads across r/Peptides, r/longevity, and r/Nootropics describe subtle energy gains, better exercise recovery, and reduced fatigue. Injection site reactions affect nearly all users.
SS-31 is a cell-permeable tetrapeptide with an alternating aromatic-cationic motif. That structure lets it cross lipid bilayers without needing mitochondrial membrane potential as a driving force. Once inside the cell, it accumulates more than 1,000-fold within mitochondria. The target is cardiolipin. This anionic phospholipid sits exclusively on the inner mitochondrial membrane, where it anchors cytochrome c and holds the electron transport chain complexes in their functional supercomplex arrangements. When cardiolipin oxidizes (a consistent hallmark of aging and mitochondrial disease), cristae flatten out. Electron transfer between complexes III and IV slows. Electrons leak sideways to form superoxide. ATP production falls. SS-31 binds directly to cardiolipin and blocks peroxidation. Cristae architecture stays intact. Electron flow through the ETC normalizes. Reactive oxygen species drop at the point of generation, not downstream. The result: improved ATP synthesis, preserved mitochondrial membrane potential, and blocked cytochrome c release, which prevents the intrinsic apoptosis cascade. In aged mice, 8 weeks of SS-31 reversed cardiac diastolic dysfunction and improved contractile reserve [2]. The TAZPOWER open-label extension [1] tracked 12 Barth syndrome patients for 168 weeks and confirmed sustained functional improvements. MMPOWER-3 (n=218)[3] tested SS-31 in primary mitochondrial myopathy; the overall primary endpoint was not met, though a nDNA-variant subgroup showed gains on the 6-minute walk test.
FDA accelerated approval granted September 19, 2025 (NDA 215244, FORZINITY) for Barth syndrome: based on open-label extension knee extensor strength improvement, NOT the randomized phase endpoints. The 12-week RCT crossover primary endpoints (6-minute walk test, total fatigue score) were NOT met. MMPOWER-3 Phase 3 (primary mitochondrial myopathy) also failed primary endpoint in the overall population; nDNA-variant subgroup showed 6MWT improvement. HFpEF NDA submitted based on PROGRESS-HFpEF trial; FDA Priority Review designation granted January 2026, PDUFA September 2026. Mechanistic evidence is very strong (cardiolipin stabilization, ROS reduction, ETC restoration). No dose-finding trial in healthy adults exists.
PMID 38602181: TAZPOWER 168-week open-label extension (Barth syndrome, n=12); PMID 37268435: MMPOWER-3 Phase 3 (PMM, n=218)
Accelerated approval contingent on confirmatory trial verifying clinical benefit. Primary RCT phase of TAZPOWER missed both endpoints. MMPOWER-3 failed overall primary endpoint. All trials conducted in disease populations (Barth syndrome, PMM, HFpEF): no RCT in healthy aging adults. Community doses (1–20 mg) are 2–40× below the studied 40 mg clinical dose with no head-to-head data. Long-term safety beyond 168 weeks unstudied. Phase 3 trial sizes are small (n=12–218) due to orphan-disease context.
Niche but growing. Primarily used by longevity/biohacking community for energy, fatigue, and exercise recovery. Reports are cautiously positive. Major barriers: dose uncertainty (0.5 mg vs 40 mg), high cost, and injection site reactions in virtually all users. Community consensus has converged around 4–10 mg/day as the "standard" research dose, with some beginning at 500 mcg–2 mg.
Science and community agree on the mitochondrial-cardiolipin mechanism. The FDA-approved 40 mg dose reflects a serious disease population; community extrapolates a lower minimum effective dose for healthy aging adults without supporting trial data. Neither confirmed nor refuted: data gap, not contradiction.
| Level | Dose / Injection | Frequency |
|---|---|---|
| Beginner | 4mg | Daily |
| Moderate | 10mg | Daily |
| Aggressive | 40mg | Daily |
Reconstitution math first. A 10 mg vial with 1 mL bacteriostatic water gives you 10 mg/mL. At that concentration, 4 mg equals 40 units on a U-100 insulin syringe (0.4 mL). A 10 mg dose takes the full syringe (100 units, 1.0 mL). For the 40 mg vial, add 4 mL BAC water for the same 10 mg/mL concentration; 10 mg is still 100 units, but you get four doses per vial instead of one. Morning dosing is the community standard. There is no meal timing requirement. You'll want to pre-treat injection sites. Cetirizine 10 mg taken 30 minutes before your shot makes a real difference for the first few weeks. Rotate between abdomen and upper thigh, and inject slowly. The site reactions are the number one reason people quit early. Get a CBC at baseline and again at week 8. The eosinophilia is expected, but you want a record showing it was absent before you started. Store lyophilized powder at minus 20 degrees Celsius. After reconstitution, keep it at 4 degrees Celsius and use within 28 days.
SS-31 does not exhibit receptor desensitization, hormonal axis suppression, or documented antibody formation. Clinical trials used continuous daily dosing for up to 168 weeks (TAZPOWER open-label extension) without cycling. Community cycling (typically 12 weeks on, 4 weeks off) is cost-driven, not biologically required.
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Expected: Modest improvement in energy and exercise recovery by weeks 4–6. Effects are subtle at this dose range: no clinical RCT data supports efficacy at 4 mg in healthy adults.
Monitor: Optional CBC at baseline and week 8 to monitor for eosinophilia. No other formal monitoring required for healthy adults at this dose.
Wash hands thoroughly and clean the vial stopper with an alcohol swab.
Draw bacteriostatic water into a syringe: 1 mL for a 10 mg vial (gives 10 mg/mL) or 4 mL for a 40 mg vial (same 10 mg/mL concentration). Inject water down the side of the vial, not directly onto the powder.
SS-31 dissolves quickly. Do not shake.
Draw your dose with a U-100 insulin syringe (29 or 30 gauge, 0.5 inch needle). At 10 mg/mL: 20 units equals 2 mg, 40 units equals 4 mg, 100 units equals 10 mg.
Clean the injection site (abdomen or upper thigh) with an alcohol swab. Let dry.
Inject slowly over 30 to 60 seconds. Slow injection reduces site reactions.
Alternate between left abdomen, right abdomen, left thigh, and right thigh.
Store reconstituted vial at 4 degrees Celsius (standard refrigerator). Use within 28 days.
No food restriction required.
Complementary mitochondrial mechanisms: SS-31 addresses cardiolipin/structural ETC function; NAD+ restores sirtuin signaling and cofactor availability. Additive without redundancy.
SS-31 morning SubQ + NAD+ SubQ 100–250 mg 2–3×/week
Dual mitochondrial optimization: SS-31 targets inner membrane cardiolipin; MOTS-c activates AMPK via nuclear retrograde signaling. Address structural and metabolic mitochondrial function together.
SS-31 daily SubQ + MOTS-c 5–10 mg 3×/week SubQ
Tissue repair synergy: BPC-157 promotes angiogenesis and cellular healing; SS-31 protects mitochondria in stressed/injured tissue. Used together in recovery and injury contexts.
SS-31 + BPC-157 250–500 mcg daily, both SubQ, separate injections
Broad anti-aging synergy: GHK-Cu supports collagen synthesis and tissue remodeling; SS-31 targets cellular energy production. Non-overlapping mechanisms.
Both target the inner mitochondrial membrane. Overlapping mechanism may produce unpredictable additive effects on membrane dynamics; no formal interaction studies.
Cyclosporine inhibits mPTP (mitochondrial permeability transition pore): overlapping mechanism with SS-31 cardiolipin stabilization. Combined effects unpredictable; no interaction data.
SS-31 mitochondrial protection may mask early cardiotoxicity signals from anthracyclines. Concurrent use requires close cardiac monitoring.
Do not combinePricing updated 2026-04-09
Injection site reactions are the defining tolerability challenge with SS-31. In the TAZPOWER trial [4], 100% of participants developed injection site erythema. 75% reported pain. 67% experienced induration. These numbers are not typical for subcutaneous peptides. Community reports confirm the clinical data: redness, swelling, and a firm lump at the injection site are expected, not exceptional. Site rotation between abdomen and upper thigh helps. Reactions typically moderate after 2 to 4 weeks of consistent use. Topical 1% hydrocortisone cream or oral cetirizine 10 mg before injection can reduce severity. Injecting slowly over 30 to 60 seconds also helps based on community experience. If induration expands, feels warm, or shows discharge, stop and evaluate for sterile abscess. Eosinophilia is the second major concern. Most users develop raised eosinophil counts after 30 or more days of SS-31, with levels peaking around day 90. This shows up on a CBC and can be alarming if unexpected. In most cases, it is asymptomatic and resolves on its own by week 16 to 20. Do not discontinue solely for isolated eosinophilia without symptoms. If wheeze, GI distress, rash, or other organ-specific symptoms appear alongside raised eosinophils, stop SS-31 and consult a physician immediately. The FDA label for FORZINITY contains a specific note about benzyl alcohol in the formulation (20 mg/mL), which must be avoided in neonates. For adults, this is not a safety concern at standard dosing. No reproductive safety data exists. SS-31 is contraindicated during pregnancy and breastfeeding. Patients with active malignancy should avoid it; effects on tumor cell mitochondria have not been studied. Those with severe cardiac conduction abnormalities were excluded from clinical trials, so safety in that population is unknown. Renal impairment matters. SS-31 is renally excreted. The FDA label calls for dose reduction to 20 mg daily for severe renal impairment (eGFR under 30, not on dialysis). Baseline renal function should be checked before starting. Long-term safety beyond 168 weeks has not been characterized. Community users running sub-clinical doses (2 to 10 mg) have less safety data coverage than trial participants at 40 mg. Lower doses likely carry lower risk, but this assumption lacks trial validation.
Verify SS-31 (Elamipretide) dosing and safety with a second opinion
SS-31 (elamipretide) is now an FDA-approved pharmaceutical (FORZINITY, NDA 215244, September 2025). IP protections may deter or legally restrict research peptide vendors from supplying it. At least one major vendor (Novo Pro Labs) listed SS-31 as discontinued due to IP conflict in 2025–2026. Pharmaceutical-grade FORZINITY is an orphan drug with prohibitive cost outside clinical use.
| Test | When | Target |
|---|---|---|
| CBC with differential | Baseline, then at week 8 and week 16 | Eosinophils <500 cells/μL (normal); mild elevation 500–1,500/μL acceptable if asymptomatic; >1,500/μL investigate for organ involvement |
| Renal function panel (BMP or CMP) | Baseline; repeat at week 12 if any renal compromise or for long-term continuous use | eGFR ≥60 for standard dosing; eGFR 30–59 monitor closely; eGFR <30 reduce dose to 20 mg/day |
| Injection site visual assessment | Each injection cycle: inspect prior site before next injection | — |
Eosinophilia occurs in majority of patients ≥30 days of SS-31 use; peaks ~day 90; typically resolves. Monitor to ensure resolution and rule out eosinophilic organ involvement.
Elamipretide is renally excreted; FDA label requires dose reduction to 20 mg/day for eGFR <30 mL/min
Near-universal injection site reactions; expanding induration, warmth, or purulent discharge may indicate sterile abscess or infection requiring intervention
SS-31 begins accumulating in mitochondrial membranes. Cardiolipin stabilization starts at the molecular level. Most users notice no outward changes yet. Injection site reactions (redness, mild soreness) are the most common early experience.
Mitochondrial ETC efficiency begins to improve. Some individuals report subtle increases in baseline energy and reduced fatigue during daily activities. ROS production at the inner membrane decreases measurably in preclinical models at this timepoint.
Clinical trial data shows measurable improvements in 6-minute walk test distance and reduced fatigue scores in Barth syndrome patients during this window. Users may notice improved exercise tolerance, better recovery from physical exertion, and more consistent energy throughout the day.
Continued improvement in mitochondrial function. Cardiac parameters such as stroke volume and cardiac output showed improvement in open-label extension studies. Skeletal muscle strength and endurance gains become more noticeable.
Long-term open-label data (up to 168 weeks in TAZPOWER) showed sustained improvements in cardiac and functional outcomes. Protocol duration beyond 12 weeks should be guided by a physician. Long-term safety beyond clinical trial settings is not fully established.
Weeks 1 to 2, Titration and Tolerance Assessment: Cardiolipin binding begins at the molecular level during this window. Electron transport chain stabilization starts, but nothing measurable shows up clinically. Most users notice zero benefits. Injection site reactions dominate the experience, with near-universal redness, pain in about 75% of users, and induration in roughly 67%. This is normal, not a reason to quit. Weeks 3 to 6, Early Mitochondrial Adaptation: Preclinical models show measurable ROS reduction and improved ATP synthesis by this point. Some users pick up on subtle energy improvements and better exercise tolerance. Post-workout fatigue may ease modestly. Injection site reactions start moderating if you are rotating sites. Eosinophilia begins appearing on CBC after 30 days of use; it is typically asymptomatic. Weeks 6 to 12, Functional Improvement Window: The TAZPOWER open-label extension recorded 16% improvement in 6-minute walk test distance and 19% improvement in fatigue scores by week 12. Knee extensor strength gained 30% from study baseline. Community users report more consistent daily energy, improved exercise performance, and better recovery. Some describe cognitive clarity. Eosinophils peak around day 90 and then begin normalizing. Weeks 12 to 24, Sustained Benefit and Stabilization: By week 36 of TAZPOWER, improvements reached 25% on the 6-minute walk test, 26% for fatigue scores, and 42% for knee extensor strength (all open-label data). Community users who continue past 12 weeks report maintained benefits. Cost fatigue leads many to take a planned break or drop to lower maintenance dosing. Eosinophilia normalizes in most users by week 16 to 20. Weeks 24 to 168 and beyond, Long-Term Maintenance: The TAZPOWER 168-week open-label extension showed sustained cardiac and functional improvements with no new safety signals in Barth syndrome patients. Long-term community data is sparse. Most people cycle for cost reasons rather than biological necessity. Benefits appear maintained in those who continue. Long-term safety in healthy aging adults has not been characterized beyond the clinical trial population.
Cardiolipin binding begins; ETC structural stabilization starts at molecular level. No measurable functional changes detectable clinically this early.
Most users report no noticeable benefits. Injection site reactions are the dominant early experience.
Preclinical models show measurable ROS reduction and improved ATP synthesis at this timepoint. Eosinophilia begins to appear on CBC (>30 days of use).
Subtle energy improvements reported by some users. Better exercise tolerance and modest reduction in post-workout fatigue. Injection site reactions begin to moderate with site rotation.
TAZPOWER open-label extension: 16% improvement in 6MWT and 19% improvement in fatigue scores by week 12; knee extensor strength +30% from study baseline.
More consistent daily energy, improved exercise performance, better recovery. Some report cognitive clarity. Peak eosinophilia around day 90.
TAZPOWER week 36: 25% improvement in 6MWT, 26% fatigue improvement, 42% knee extensor strength increase from study baseline (open-label data).
Maintained benefits. Cost fatigue leads many to take a planned break or transition to lower maintenance dosing. Eosinophilia normalizes in most users.
TAZPOWER 168-week open-label extension showed sustained cardiac and functional outcome improvements with no new safety signals.
Long-term community data is sparse. Most cycle for cost reasons rather than safety. Benefits appear maintained in long-term users.
Source: Plasma elimination half-life of ~4 hours after subcutaneous administration in human clinical trials (PMID 29500292)
Loading the interactive decay curve.
SS-31 (elamipretide) received FDA accelerated approval on September 19, 2025 under the brand name FORZINITY (NDA 215244) for treatment of Barth syndrome in adults and pediatric patients weighing at least 30 kg. Continued approval is contingent on a confirmatory clinical trial verifying clinical benefit. FORZINITY is manufactured by Stealth BioTherapeutics. An additional NDA for heart failure with preserved ejection fraction (HFpEF) was submitted based on the PROGRESS-HFpEF trial; FDA granted Priority Review designation in January 2026 with a PDUFA target date of September 2026. Research peptide vendors have historically supplied SS-31 under various names (SS-31, MTP-131, Bendavia). Following FDA approval, some vendors have discontinued SS-31 due to intellectual property conflict concerns. Availability from research sources may become increasingly restricted. SS-31 is sold for research purposes only through non-pharmaceutical channels. It is not WADA-listed as of early 2026, though athletes should verify current prohibited substance lists before use. This content is for educational and informational purposes only and does not constitute medical advice. Consult a qualified healthcare provider before using any peptide.
Peptide Schedule Research TeamReviewed Apr 20269 Citations
