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Some human trialsFDA approved as Forzinity

SS-31 side effects

Also known as: SS31 · SS 31 · Elamipretide · Elamipretide hydrochloride · MTP-131 · Bendavia · Forzinity

Updated 93 sources

10 side effects reported for SS-31: 6 from studies and labels, 4 from users and guides. 5 come with the ways people manage them.

SS-31 overview

Side effects reported in studies and labels

Rates as each trial or label states them. A rate from one trial does not carry over to research-grade vials or other doses.

From trials and regulators6

Clinical studies and regulatory documents.

  • Injection-site reactions (Barth trial, FDA label)

    Any local reaction 100% on drug vs 67% placebo: redness 100% vs 25%, pain 75% vs 42%, hardening and itching 67% vs 17%, bruising and hives 25% vs 0%.

    How people manage it

    • The label says mild to moderate skin reactions can be treated with topical corticosteroids and oral antihistamines.
    • Rotate injection sites every day.

  • Injection-site reactions (mitochondrial myopathy trial)

    MMPOWER-2: 80% had a reaction, mostly mild. Redness 56.7% vs 3.3% on placebo, itching 46.7% vs 0%, pain 20% vs 3.3%, hives 20% vs 0%. One person dropped out for injection pain.

  • Eosinophil rise

    Common with 30 or more days of use, peaking around day 90 (mean rise about 0.5 to 0.6 x10^3/uL). Back to baseline after 6 to 12 months and not tied to symptoms.

  • Serious allergic reaction

    Reported on the label, from minutes to months after starting. No rate given.

    How people manage it

    • Stop for a serious allergic reaction and do not restart.

  • Dizziness

    MMPOWER-2: 10% vs 3.3% on placebo.

  • Stopping for side effects (MMPOWER-3)

    7.3% stopped for adverse events vs 1.8% on placebo. Serious events 4.6% vs 2.8%, none judged drug-related. Injection-site reactions were the most common.

Side effects users and guides report

What people post and what dosing guides list. These are reports, not measured rates.

From users and guides4

Community reports, competitor and vendor guides, media.

  • Red, itchy lump at the injection site

    Reported on r/Peptides, lasting about 30 minutes. Another user says higher amounts may irritate the site.

  • Fatigue

    The most-posted complaint on r/Peptides, at every dose from 500 mcg to 6 mg; one user felt tired and dizzy at 2 mg. Some say it fades after a few weeks. Guides list early fatigue lasting 1 to 3 weeks.

    How people manage it

    • One user moved the dose to bedtime.
    • A guide suggests cutting the dose by 25 to 50% for moderate effects and stopping for severe ones.

  • Overstimulation or insomnia

    Reported on r/Peptides: 2-hour sleep blocks, anxious evening energy at 1 mg, jitters at 25 mg.

    How people manage it

    • Dose in the morning only.
    • One user dropped from 1 mg to 0.5 mg for two weeks and the anxious energy settled.
    • Users mention L-theanine or melatonin.

  • Headache, dizziness or mild nausea

    Listed by dosing guides with no rates.

    How people manage it

    • Cut the dose by 25 to 50% for moderate effects; stop for severe ones.

Who should avoid it, and what not to combine

  • Severe kidney impairment or dialysisCondition

    Exposure rises 39%, 75% and 125% with mild, moderate and severe impairment, and two metabolites rise up to 280% and 640% in severe impairment. The label cuts the dose to 20 mg below an eGFR of 30 and gives no dose on dialysis.

  • NewbornsCondition

    The approved solution contains benzyl alcohol as a preservative.

  • Past serious allergic reaction to elamipretideCondition

    The label says stop for serious hypersensitivity and do not restart.

  • Other products in the same syringeSubstance

    The label says not to mix it with other products in one syringe.

How much is known

Some human trials

Several randomized trials, most of which missed their main goals. The Barth approval rests on strength gains in an open-label extension, not the 12-week randomized part. MMPOWER-3 (218 people, 24 weeks) missed both primary endpoints. MMPOWER-2 missed the walk test; fatigue improved nominally, then faded after stopping. One IV dose raised muscle ATP output 27% vs 12% on placebo, gone by day 7. No trials in healthy people, athletes or at community doses.

Sources for these side effects

18 sources, each checked by date. Record updated Oct 23, 2026. Numbers are restated in our own words and labelled by where they came from.

Clinical study2

  1. Karaa A et al., MMPOWER-2 randomized crossover trial of elamipretidePubMed Central · checked Oct 23, 2026
  2. Despite failure to meet end points, elamipretide results offer further insight (MMPOWER-3)NeurologyLive, via a news report · checked Oct 23, 2026

Regulatory2

  1. Forzinity (elamipretide) prescribing information, NDA 215244FDA · checked Oct 23, 2026
  2. Forzinity drug information (label reproduction)Guideline Central, via a reference work · checked Oct 23, 2026

Competitor guide3

  1. SS-31 side effectsbodyhackguide.co · checked Oct 23, 2026
  2. SS-31 protocolpeptidedosingprotocols.com · checked Oct 23, 2026
  3. SS-31 protocolpathtopeptides.com · checked Oct 23, 2026

Community-reported11

  1. SS-31 or MOTS-c: red itchy lumpr/Peptides · checked Oct 23, 2026
  2. Comment: 4 mg 5 on 2 off, injection irritation at higher amountsr/Peptides · checked Oct 23, 2026
  3. SS-31 tiredness at 500 mcg to 1 mgr/Peptides · checked Oct 23, 2026
  4. SS-31 at 2 mg, tired and dizzyr/Peptides · checked Oct 23, 2026

Back to the full SS-31 page for dosing, the vial chart and storage.