SS-31 (Elamipretide): What Lakeland Readers Should Know

SS-31, now called elamipretide, is a small lab-made peptide that targets mitochondria, the energy-making parts of cells. In 2025 FDA approved it, as Forzinity, for one very rare inherited disease. It is promoted online for energy and healthy aging, but the evidence does not support those uses. This page is general information, not advice for your situation.

What it is and how it works

Elamipretide is a chain of just four amino acids. It has also been called SS-31 (Szeto-Schiller peptide), MTP-131 and Bendavia. It is made by Stealth BioTherapeutics and sold as Forzinity.¹²

It binds to cardiolipin, a fat in the inner wall of mitochondria. Its label says it “improves mitochondrial morphology and function.”¹

Its approved use is Barth syndrome. This is a rare, serious inherited disease caused by defects in the TAZ gene, which disrupt cardiolipin.³ It mainly affects males and often begins with heart failure in infancy.⁴ FDA estimates about 150 people in the U.S. have it.⁵

What the research shows (and where evidence is weak)

Barth syndrome, randomized phase. The key trial enrolled 12 patients in a randomized, double-blind crossover. That means each person took the drug and a placebo (dummy treatment) for 12 weeks each, in random order, without knowing which was which. The drug did not beat placebo on either main goal: walking distance or fatigue. Knee-muscle strength did not rise during this phase.¹³

Barth syndrome, open-label extension. Ten patients then stayed on the drug, with no comparison group and everyone aware they were taking it. Eight reached week 168. From a starting median of 124 newtons, median knee-muscle strength rose by 68 newtons at week 24 and 63 newtons at week 168.¹ Study authors, some employed by the company, also reported walking gains.⁶

FDA’s internal debate. FDA’s own clinical and statistical reviewers recommended against approval. They pointed to the open-label design, the lack of a control group, dropouts and tests that depend on effort. The senior FDA official approved it anyway, accepting “more uncertainty than we would accept for more common diseases” because the disease is very rare and serious, with no approved treatment.⁵ Earlier, in October 2024, an FDA advisory committee voted 10 to 6 that the drug is effective for Barth syndrome.⁵

A more common disease. In primary mitochondrial myopathy, a phase 3 trial randomized 218 adults to elamipretide or placebo for 24 weeks. It did not meet its main goals on walking distance or fatigue. The authors called this strong (Class I) evidence that the drug does not improve those measures in that disease. A possible benefit appeared only in a subgroup picked after the fact.⁷

We found no controlled trial testing elamipretide in healthy people for energy, aging or athletic performance.

FDA and regulatory status

• Approval. On September 19, 2025, FDA granted accelerated approval to Forzinity “to improve muscle strength in adult and pediatric patients with Barth syndrome weighing at least 30 kg.” FDA called it the first treatment for Barth syndrome.⁸⁴
• What “accelerated” means here. The drug was approved under accelerated approval based on knee-muscle strength, an in-between measure. A confirmatory trial is required. The company must run a randomized, placebo-controlled trial, with completion planned for September 2029, and FDA may withdraw the approval if it fails to confirm a benefit.⁸¹
• A separate fact. Its earlier randomized trial did not show a benefit over placebo, as described above.¹
• Path to approval. FDA first declined to approve it on May 15, 2025. The company resubmitted on August 15, 2025.⁸
• No other approved use. It has no FDA-approved use outside Barth syndrome.⁸
• Online “SS-31.” In August 2026, FDA warned a Sarasota, Florida seller that its “SS-31 (Elamipretide)” product was an unapproved new drug. FDA said a “for research use only” label does not change that when a website shows the product is meant for people.⁹
• Sport. Elamipretide is not named on the World Anti-Doping Agency’s 2026 Prohibited List.¹⁰ Athletes should still check with their anti-doping organization.

Common side effects and safety

From the Forzinity label:¹

• Injection-site reactions are very common. In the Barth trial, all 12 patients (100%) had redness at the injection site on the drug, compared with 3 of 12 (25%) on placebo.
• Serious allergic reactions have been reported, including some needing emergency care. They can happen within minutes or months after starting. People with a serious allergy to the drug should not use it.
• Eosinophils, a type of white blood cell, often rose, peaking around 90 days.
• Not for newborns, because of a preservative (benzyl alcohol) that can be toxic to them.

In a 48-week trial in another mitochondrial disease, injection-site redness occurred in 51% on the drug vs 8% on placebo.⁵

“SS-31” sold online is not the same as the approved product. See our guide to research-chemical peptide risks.

Typical cost range

Forzinity is a very expensive specialty drug. A Missouri Medicaid document dated April 14, 2026 listed its wholesale price at $4,360.27 per mL, or $795,749.28 per year.¹¹ That is a list price, not what a patient pays. Coverage for an approved rare-disease use depends on the plan. Our guide to insurance and HSA/FSA explains the basics.

Prices for products sold as “SS-31” outside the approved drug supply are not reliable. Prices vary between clinics and pharmacies. Ask any provider for a written price breakdown before you start.

Questions to ask a provider

• Do I have a condition that elamipretide is approved for? If not, what evidence supports using it for me?
• Is this the FDA-approved product, Forzinity, or something else? Where does it come from?
• How will you watch for allergic reactions and injection-site problems?
• What do the negative randomized trials mean for my situation?
• What will it cost, and will insurance cover it?

Our guide on how to vet a peptide clinic can help you spot red flags.