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What is SS-31 (elamipretide)?

SS-31 explained in plain English: what it is, what the research shows, side effects, legal status and dosage, plus a calculator for syringe units. Doses shown come only from the label or published trials, each with its source. Also called Elamipretide, Forzinity, Bendavia, MTP-131.

SS-31 (elamipretide) is FDA-approved as Forzinity only for Barth syndrome. SS-31 sold online as a research peptide is not an approved product. This page is educational; talk with a qualified healthcare professional.

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= 10,000 mcg

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Syringe, no result yetU-100, 1 mL syringe holding up to 100 units. Enter your dose.0102030405060708090100

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What is SS-31?

SS-31 is a small lab-made peptide, four amino acids long, that targets the mitochondria, the parts of cells that make energy. Its drug name is elamipretide, and it is sold as the prescription medicine Forzinity.

It was developed by Stealth BioTherapeutics and was known as SS-31, Bendavia and MTP-131 during research. In September 2025 it became the first FDA-approved medicine that targets mitochondria directly.

What is SS-31 used for?

SS-31 is FDA-approved only for Barth syndrome, a rare inherited disease that weakens the heart and muscles because mitochondria don’t work properly. The approval covers adults and children who weigh at least 30 kg.

Outside that use, SS-31 is sold online as a research peptide for energy, endurance and anti-aging. Those uses haven’t been tested in approved trials.

How does SS-31 work?

SS-31 binds cardiolipin, a fat found in the inner membrane of mitochondria. That is thought to keep the energy-making machinery working more efficiently and to reduce the harmful byproducts mitochondria produce under stress.

What does the research on SS-31 show?

The approval was an accelerated approval, based on improved strength in the thigh muscle that straightens the knee in the TAZPOWER trial. The FDA considered that likely to predict benefits like standing or walking farther, and the company has to confirm it in further studies.

Earlier trials in other mitochondrial muscle diseases and in heart failure did not meet their main goals. There is no good evidence that SS-31 slows aging in healthy people.

SS-31 side effects and risks

The most common side effects in trials were injection-site reactions, such as redness, itching and pain where it was injected. Its long-term effects in healthy people using research versions are unknown.

Research peptides sold as “SS-31” aren’t the approved product, and nobody checks their purity or strength.

Yes, as the prescription medicine Forzinity, for Barth syndrome. SS-31 powders sold online for research are not approved for human use.

How do you reconstitute SS-31?

SS-31 research vials hold a freeze-dried powder that is mixed with bacteriostatic water. The calculator above turns the vial size, the water and a dose into syringe units, and the reconstitution guide explains each step.

See the dosage section below for what is known about doses, with sources.

SS-31 dosage

Forzinity is injected under the skin once a day. The label dose applies to people with Barth syndrome who weigh at least 30 kg; there is no approved dose for any other use.

From the official prescribing information (label). Your prescriber decides your dose and when to change it.

SS-31 doses, with sources
WhenDoseHow often
Barth syndrome, patients 30 kg or more40 mg[1]Once a day, under the skin
  1. Pharmacy Times (2025), elamipretide approval and label dose

Medical disclaimer: this dosage information is for education only and comes from the source shown for each row. It is not medical advice and not a recommendation for you. Only a licensed prescriber who knows your health can decide whether SS-31 is right for you and at what dose. Don't start, change or stop a medicine based on this page, and don't use research peptides or unapproved drugs based on trial doses.

SS-31 concentration chart

The concentration of a SS-31 vial depends only on its size and the water you add. Each unit on a U-100 syringe holds one hundredth of a mL.

SS-31 concentration by vial size and water
Vial + waterConcentrationPer unit (U-100)
10 mg + 1 mL10,000 mcg/mL (10 mg/mL)100 mcg per unit (0.1 mg per unit)
10 mg + 2 mL5,000 mcg/mL (5 mg/mL)50 mcg per unit (0.05 mg per unit)
10 mg + 3 mL3,333.33 mcg/mL (3.33333 mg/mL)33.33 mcg per unit (0.03333 mg per unit)
50 mg + 1 mL50,000 mcg/mL (50 mg/mL)500 mcg per unit (0.5 mg per unit)
50 mg + 2 mL25,000 mcg/mL (25 mg/mL)250 mcg per unit (0.25 mg per unit)
50 mg + 3 mL16,666.67 mcg/mL (16.66667 mg/mL)166.67 mcg per unit (0.16667 mg per unit)

Frequently asked questions

Is SS-31 FDA approved?

Yes, but only for one rare disease. In September 2025 the FDA gave elamipretide (Forzinity) accelerated approval for Barth syndrome in patients weighing at least 30 kg.

What is SS-31 used for?

Its approved use is Barth syndrome, a rare inherited mitochondrial disease. Online it is sold for energy and anti-aging, uses that have not been proven or approved.

How does SS-31 work?

It binds cardiolipin, a fat in the inner membrane of mitochondria, which is thought to help mitochondria make energy more efficiently and produce fewer harmful byproducts.

Sources

  1. FDA (2025), FDA grants accelerated approval to first treatment for Barth syndrome
  2. Pharmacy Times (2025), FDA Grants Accelerated Approval to Elamipretide

Last updated .

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