Adverse effect · SS-31 (elamipretide)

How common is safety in humans with SS-31 (elamipretide)?

C
Grade C — weak human evidenceAcross the trial programme · effect size: small · adverse
Short answerWeak human evidence. Across the trial programme: enough to be interesting, not enough to count on. Where an effect is seen it is a small effect. Consistently well tolerated across trials; the main issue is injection-site reactions. Long-term safety data come mostly from the small Barth open-label extension.

What the studies show

Consistently well tolerated across trials; the main issue is injection-site reactions. Long-term safety data come mostly from the small Barth open-label extension.

“Elamipretide treatment was well-tolerated with most adverse events being mild to moderate in severity.”

Verbatim, from the abstractKaraa A, et al. Efficacy and safety of elamipretide in individuals with primary mitochondrial myopathy: the MMPOWER-3 randomized clinical trial. Neurology, 2023;101:e238–e252

A few small or poorly-controlled human studies. Enough to be interesting; not enough to count on. Most of what gets called “clinically proven” online lives here.

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In context

SS-31, developed as elamipretide, is a four-amino-acid peptide that concentrates in mitochondria and binds cardiolipin, a lipid of the inner membrane. After a decade of trials it was approved in the United States in September 2025 for Barth syndrome, an ultra-rare genetic disease — on the strength of an open-label extension, since its randomised crossover missed both primary endpoints. Larger randomised trials in primary mitochondrial myopathy and in heart failure were negative. It is a genuine, narrowly approved medicine, not a general 'mitochondrial' or anti-ageing treatment.

SS-31 (elamipretide) is approved (rx, us; barth syndrome only). Legal status differs by country — see the regulation section or the jurisdiction pages.

Questions

Is SS-31 (elamipretide) proven to cause safety in humans?
No. The human evidence is weak (Across the trial programme); LYO grades it C.
What studies are behind the grade?
Consistently well tolerated across trials; the main issue is injection-site reactions. Long-term safety data come mostly from the small Barth open-label extension.
Is SS-31 (elamipretide) approved for this?
SS-31 (elamipretide) is an approved medicine (Approved (Rx, US; Barth syndrome only)); whether this particular outcome is a licensed indication is stated on the compound page's regulation section.

Other outcomes for SS-31 (elamipretide)

Written and maintained by LYO Research — how pages are written and checked. Reviewed 3 September 2026. Grades count human evidence only; see how LYO grades. Not medical advice. Correct this page →