SS-31 Peptide (Elamipretide): What It Is, How It Works, and What the Evidence Shows

SS-31, also called elamipretide, MTP-131, or Bendavia, is a synthetic four-amino-acid peptide that concentrates in the inner mitochondrial membrane and binds cardiolipin. By stabilizing cardiolipin, it may support the electron transport chain, ATP production, and lower oxidative stress. It is investigational, not FDA-approved, and has been studied mainly in mitochondrial and cardiac diseases 1.

What is SS-31 peptide?

SS-31 is a mitochondria-targeted antioxidant peptide. It is called a Szeto-Schiller peptide because it came from research by Hazel Szeto and Peter Schiller on small peptides that can enter mitochondria and protect mitochondrial function 1.

You may see the same compound listed as elamipretide, MTP-131, or Bendavia. Stealth BioTherapeutics has developed elamipretide in clinical trials for rare mitochondrial diseases and heart conditions 3, 4, 5.

How it differs from receptor-based peptides

Many peptides work by binding a cell-surface receptor, like a key fitting a lock. SS-31 works differently. It is designed to concentrate inside mitochondria and interact with cardiolipin, a special fat in the inner mitochondrial membrane 2.

That distinction matters. SS-31 is not a hormone peptide, appetite peptide, or growth-hormone secretagogue. It is best understood as a mitochondria-targeted peptide being studied for diseases where mitochondrial energy production is impaired.

How does SS-31 work in the body?

Elamipretide appears to work by binding cardiolipin and helping stabilize the inner mitochondrial membrane. In preclinical and human tissue research, this has been linked with better electron transport chain structure, less reactive oxygen species, and improved ATP handling 2, 6.

Cardiolipin and the inner mitochondrial membrane

Mitochondria make most of the cell’s usable energy. The inner mitochondrial membrane is where the electron transport chain sits, and cardiolipin helps hold that machinery in the right shape 2.

When cardiolipin is damaged by oxidative stress, energy production can become less efficient. In model systems, SS-31 binds cardiolipin and may help protect the structure of the membrane, which is why it is called a mitochondria-targeted antioxidant 2.

Effect on ATP and reactive oxygen species

ATP is the cell’s main energy currency. Reactive oxygen species, or ROS, are unstable molecules made during normal energy production. Some ROS are normal, but excess ROS can damage cell parts.

In animal and lab studies, SS-31 has been associated with lower mitochondrial ROS and improved ATP-related measures, especially under stress conditions 6. Human trials are the harder test, and those results have been mixed across diseases 3, 4, 5.

Why it may not affect healthy mitochondria the same way

A useful way to think about SS-31 is that it has been studied most where mitochondrial stress is already present. In healthier tissue, there may be less damaged cardiolipin or less oxidative stress to modify. That is one reason we should not assume trial results in rare disease apply to healthy adults seeking more energy.

What conditions has SS-31 been studied for?

SS-31 has been studied mainly in conditions tied to mitochondrial dysfunction, including primary mitochondrial myopathy, Barth syndrome, and heart failure. These studies do not prove general longevity, energy, or weight-loss benefits for otherwise healthy adults.

Primary mitochondrial myopathy

Primary mitochondrial myopathy is a group of genetic disorders where mitochondria do not make energy normally in muscle. In the MMPOWER-2 trial, participants received elamipretide 40 mg by subcutaneous injection once daily for 48 weeks; the study reported improvements in some patient-reported fatigue and function measures, but the field still needed larger controlled data 3.

In the later MMPOWER-3 phase 3 trial, elamipretide 40 mg once daily did not meet its main endpoints for six-minute walk distance or a primary fatigue score compared with placebo 7. Individual results vary, and these trial findings should not be read as advice to use SS-31 outside a clinical study.

Barth syndrome

Barth syndrome is a rare genetic disease that affects cardiolipin remodeling. Because SS-31 binds cardiolipin, it is a biologically plausible target for this condition. In the TAZPOWER study, boys and young men with Barth syndrome received elamipretide 40 mg once daily in a randomized withdrawal design, followed by open-label treatment; the trial reported changes in exercise and patient-reported measures that supported further study 4.

The FDA granted elamipretide Rare Pediatric Disease designation for Barth syndrome, a status used for certain serious diseases that mainly affect children 8. That designation is not the same as FDA approval.

Heart failure

In the EMBRACE-HF trial, adults with heart failure with reduced ejection fraction received elamipretide by subcutaneous injection for 12 weeks. The study did not show a significant improvement in left ventricular end-systolic volume compared with placebo, though it helped define safety and dosing for later research 5.

Kidney, neurological, and age-related research

SS-31 has also been studied in kidney injury, neurodegeneration models, skeletal muscle aging, and other mitochondrial stress settings. Much of this work is preclinical, meaning it comes from cells or animals, not large human trials 6, 9. For general longevity use, the honest answer is that strong human outcome data are not established.

Is SS-31 FDA-approved or available by prescription?

Elamipretide is not FDA-approved for general use. It has been studied in clinical trials and has received rare-disease regulatory designations, but those designations do not mean it can be prescribed like an approved medication 8.

At Chia, SS-31 is education-only because it is not part of our current catalog. We do not prescribe it, compound it, or ship it.

Clinical trial status and Rare Pediatric Disease designation

A drug can be in clinical trials for years before regulators decide whether benefits outweigh risks for a specific use. Rare Pediatric Disease designation can support development for serious pediatric conditions, but it is not a finding of safety or efficacy 8.

Compounded peptides and the current US landscape

Some peptides can be prescribed as compounded medications when a licensed clinician determines they are appropriate and a state-licensed 503A pharmacy compounds them for an individual patient. But not every investigational peptide is available through that pathway, and SS-31 is not in Chia’s catalog.

The safer access line is licensed versus unlicensed. A licensed provider and a state-licensed pharmacy are different from no-prescription “research chemical” sellers, where identity, sterility, and potency may be unclear.

How is SS-31 dosed and administered in studies?

SS-31 has most often been studied as a subcutaneous injection, meaning an injection under the skin. Published trials have used study-specific regimens, not consumer protocols.

Subcutaneous injection in clinical trials

In MMPOWER-2, adults with primary mitochondrial myopathy received elamipretide 40 mg once daily by subcutaneous injection for 48 weeks 3. In MMPOWER-3, the same 40 mg once-daily subcutaneous dose was evaluated in a phase 3 placebo-controlled trial 7.

In TAZPOWER for Barth syndrome, the study also used elamipretide 40 mg once daily by subcutaneous injection 4. These numbers describe research protocols. They are not instructions for personal use.

Why individualized, provider-guided dosing matters

Peptide dosing depends on the condition studied, kidney and liver health, other medications, adverse effects, and the product’s legal status. For an investigational compound like SS-31, personal use outside a trial carries added uncertainty.

This article does not provide personal dosing advice

We do not recommend a dose, cycle length, or injection schedule for SS-31. If you have a mitochondrial disease or rare disease diagnosis, the right next step is care from a specialist or a registered clinical trial site.

What are the known side effects and safety considerations?

Elamipretide has been studied in several human trials, and common adverse events have included injection-site reactions. Safety findings are still tied to specific trial populations, so they should not be over-applied to healthy people or unregulated products.

Injection-site reactions

In the Barth syndrome TAZPOWER study, injection-site reactions were among the commonly reported adverse events during elamipretide treatment 4. In mitochondrial myopathy trials, local reactions and other adverse events were tracked as part of the safety assessment 3, 7.

What Phase II and Phase III data show

Across trials, elamipretide has generally been studied with structured monitoring, defined inclusion criteria, and adverse-event reporting. That is very different from using an unverified peptide product without clinician oversight.

Benefits and risks must be considered together. The same trials that tested fatigue, walking distance, cardiac structure, or exercise measures also tracked adverse events and found that efficacy results varied by disease and endpoint 4, 5, 7.

Who should not use SS-31

Because SS-31 is investigational and not FDA-approved for general use, there is no broad FDA label listing standard contraindications. People who are pregnant, trying to become pregnant, breastfeeding, have serious medical conditions, or take complex medication regimens should not use investigational peptides without specialist oversight.

How does SS-31 compare with NAD+, glutathione, and sermorelin?

SS-31 is different from NAD+, glutathione, and sermorelin because it directly targets the mitochondrial inner membrane and cardiolipin. NAD+, glutathione, and sermorelin are broader longevity and metabolic-support options, and Chia offers those through licensed online care where clinically appropriate.

For patients comparing SS-31 vs NAD+ for mitochondrial health, the key difference is target. SS-31 is a cardiolipin-focused investigational peptide. NAD+ is part of normal energy chemistry across many cells, and Chia offers NAD+ injection and nasal spray through licensed-provider review.

Can SS-31 help with weight loss or energy?

SS-31 should not be viewed as a proven weight-loss medication. Its human research has focused on mitochondrial diseases and heart failure, not body-weight reduction in the general population 3, 5, 7.

Energy is more nuanced. In mitochondrial myopathy studies, researchers measured fatigue, walking distance, and patient-reported function, but results were mixed and tied to rare disease populations 3, 7. That does not establish a general “energy peptide” effect for healthy adults.

For weight management, GLP-1 medicines have a different evidence base and mechanism. Semaglutide is a GLP-1 receptor agonist studied for chronic weight management at a target FDA-label dose of 2.4 mg once weekly, with gastrointestinal side effects and important contraindications noted in the FDA label 13. Chia offers compounded semaglutide injection with microdosing plans available, but compounded formulations are not FDA-approved and do not have FDA-evaluated outcomes data.

If the main concern is fatigue, weight change, sleep, mood, or exercise tolerance, a clinician should first look for common causes such as thyroid disease, anemia, sleep apnea, medication effects, depression, menopause symptoms, diabetes, and low calorie or protein intake.

How can you access mitochondrial and longevity peptides through a licensed provider?

Chia does not currently offer SS-31, but we do evaluate patients online for adjacent longevity and mitochondrial-support options in our catalog. These include NAD+, glutathione, sermorelin, and the Foundation Longevity protocol, which combines sermorelin injection, NAD+ injection, and glutathione injection.

Here is how treatment at Chia works: you complete a short online health questionnaire, then a licensed US provider reviews your history and goals. If a prescription is clinically appropriate, medication is compounded by a US state-licensed 503A pharmacy and shipped to your door. A prescription is never guaranteed.

Dosing is provider-guided and adjusted over time. Patients can message their care team through the patient portal between visits. Compounded medications are not FDA-approved.

Why is SS-31 peptide so expensive?

Elamipretide is expensive partly because it is an investigational peptide tied to rare-disease drug development, specialized manufacturing, clinical trials, and regulatory work. Cost also rises when a peptide requires careful synthesis, purity testing, sterile handling, and cold-chain storage.

Low-price no-prescription products may not solve that problem. With unlicensed sellers, the concern is not just price. It is whether the vial contains the stated peptide, at the stated strength, without contamination.

How long should someone take SS-31?

SS-31 duration has only been defined in study protocols, not as a general wellness cycle. Trials have used periods such as 12 weeks in heart failure and 48 weeks in primary mitochondrial myopathy, with structured safety monitoring 3, 5.

There is no evidence-based public rule for how long a person should take SS-31 for energy, longevity, or weight loss. For investigational peptides, the safer frame is clinical trial participation or specialist care, not self-directed long-term use.

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