Short answer: SS-31 is now an approved drug. On September 19, 2025, the US FDA granted accelerated approval to elamipretide (brand name Forzinity) as the first treatment for Barth syndrome, a rare inherited mitochondrial disease. That makes SS-31 the first mitochondria-targeted peptide to reach the market. The most common side effects in its trials were mild to moderate injection-site reactions. The approval is narrow and conditional, and it says nothing about use for anti-aging or performance.
What SS-31 does
SS-31 (Szeto-Schiller peptide 31) is a four-amino-acid peptide (D-Arg-Dmt-Lys-Phe-NH₂) designed by Hazel Szeto and Peter Schiller. It crosses into cells and concentrates on the inner mitochondrial membrane, where it binds cardiolipin, a lipid that holds the energy-producing machinery together. By stabilizing cardiolipin, it is thought to improve how mitochondria produce energy and reduce the oxidative damage they generate. For how it fits with other mitochondrial compounds, see MOTS-c, SS-31 and NAD+.
The 2025 FDA approval
| Detail | |
|---|---|
| Drug | Forzinity (elamipretide) injection, Stealth BioTherapeutics |
| Date | September 19, 2025 |
| Indication | Barth syndrome, in patients weighing at least 30 kg |
| Type | Accelerated approval, based on improved knee-extensor muscle strength |
| Condition | A confirmatory randomized, placebo-controlled trial is required |
The trials that did not succeed
Elamipretide’s path was long. Before Barth syndrome, it was tested in primary mitochondrial myopathy, heart failure and other conditions, and several of those trials missed their main goals. That history is a useful reminder: a compelling mechanism in mitochondria does not automatically translate into clinical benefit, and the approval rests on one rare disease.
Side effects
- Injection-site reactions (redness, itching, pain, swelling) were the most common side effect, mostly mild to moderate. In earlier trials they were very frequent with daily injections.
- The FDA notes that serious reactions have been reported; the full prescribing information lists them.
- Effects in healthy people using it for longevity or performance have not been studied.
| FDA (USA) | Approved (accelerated) for Barth syndrome only, by prescription. |
|---|---|
| Health Canada | Not approved in Canada. SS-31 is named in Health Canada’s April 2026 advisory on unauthorized injectable peptides. |
See TrueLabs SS-31 and its COA →
Frequently asked questions
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Is SS-31 the same as elamipretide?
Yes. SS-31 is the research name for elamipretide, approved in the US as Forzinity.
Is SS-31 FDA approved?
Yes, since September 19, 2025, as an accelerated approval for Barth syndrome in patients weighing at least 30 kg. A confirmatory trial is required.
What are the side effects of SS-31?
The most common side effects were mild to moderate injection-site reactions. The FDA notes that serious reactions have also been reported.
How does SS-31 work?
It concentrates on the inner mitochondrial membrane and binds cardiolipin, which is thought to stabilize energy production and reduce oxidative damage.
Is SS-31 approved in Canada?
No. It is not approved in Canada and is named in Health Canada’s April 2026 advisory on unauthorized injectable peptides.
Related reading
References
- US FDA. FDA grants accelerated approval for first treatment for Barth syndrome. September 19, 2025. FDA
- Szeto HH. First-in-class cardiolipin-protective compound as a therapeutic agent to restore mitochondrial bioenergetics. Br J Pharmacol. 2014. PubMed
- Health Canada. Think twice before injecting peptides bought online. April 9, 2026. Health Canada
All TrueLabs products are sold for in vitro and laboratory research use only. They are not intended for human or veterinary use, and nothing in this article is medical advice.