The short answer
Both work on mitochondria, from different sides: MOTS-c is a peptide encoded by mitochondrial DNA that, in mice, activates AMPK, the pathway exercise triggers; SS-31 binds cardiolipin in the inner mitochondrial membrane and, in cell and animal studies, cuts oxidative stress. SS-31 is FDA-approved as elamipretide (Forzinity) for the rare disease Barth syndrome. MOTS-c is taken 2–3 times a week, SS-31 daily.
Side by side
| Compared | MOTS-c | SS-31 |
|---|---|---|
| Category | Longevity | Longevity |
| Also known as | Mitochondrial Open Reading Frame of the 12S rRNA-c | Elamipretide, Szeto-Schiller 31, MTP-131 |
| What it is | A peptide encoded by your mitochondrial DNA, the energy-producing organelles inside every cell. | A mitochondria-targeting peptide that binds directly to cardiolipin — a key lipid in the inner mitochondrial membrane where your cells generate energy. |
| How it works | Mitochondria-derived peptide that regulates metabolic homeostasis. In mouse and cell studies it activates the AMPK pathway, improves insulin sensitivity and exercise capacity, and slows some signs of aging. | Mitochondria-targeting peptide that binds cardiolipin in the inner mitochondrial membrane. Improves mitochondrial function and reduces oxidative stress (cell and animal studies). FDA-approved in 2025 (accelerated) for Barth syndrome, and in trials for dry AMD. |
| Commonly reported | More energy and better workout endurance over the first weeks, sometimes after a week or two of feeling tired. No human trial has tested it yet. | Injection-site redness, itching or welts (very common), and for some, steadier stamina with less post-exertion crash over weeks. |
| Studied range | Research range: 5–10 mg. Studied in research — not a recommendation. | Research range: 2–4 mg. Studied in research — not a recommendation. FDA-approved as Forzinity (elamipretide): 40 mg SubQ once daily, to improve muscle strength in adults and children with Barth syndrome who weigh at least 30 kg (accelerated approval). |
| How often | 2–3× weekly | Daily |
| Half-life | Hours (short) | Short (hours) |
| Route | SubQ injection, IM injection | SubQ injection |
| Typical run | 4–8 week cycles common, 2–3× per year. Common splits: Mon/Thu (2× weekly) or Mon/Wed/Fri (3× weekly). Limited long-term human data — none on continuous dosing. | Daily or EOD use. Cycles of 4–8 weeks common; some run continuously. The Forzinity label doses it once daily with no break. |
| Evidence | Emerging: primarily preclinical / limited human data | Emerging: primarily preclinical / limited human data |
| Common side effects | Injection site reaction, mild fatigue first week | Injection site reaction, nausea, mild headache |
- Category
- MOTS-cLongevity
- SS-31Longevity
- Also known as
- MOTS-cMitochondrial Open Reading Frame of the 12S rRNA-c
- SS-31Elamipretide, Szeto-Schiller 31, MTP-131
- What it is
- MOTS-cA peptide encoded by your mitochondrial DNA, the energy-producing organelles inside every cell.
- SS-31A mitochondria-targeting peptide that binds directly to cardiolipin — a key lipid in the inner mitochondrial membrane where your cells generate energy.
- How it works
- MOTS-cMitochondria-derived peptide that regulates metabolic homeostasis. In mouse and cell studies it activates the AMPK pathway, improves insulin sensitivity and exercise capacity, and slows some signs of aging.
- SS-31Mitochondria-targeting peptide that binds cardiolipin in the inner mitochondrial membrane. Improves mitochondrial function and reduces oxidative stress (cell and animal studies). FDA-approved in 2025 (accelerated) for Barth syndrome, and in trials for dry AMD.
- Commonly reported
- MOTS-cMore energy and better workout endurance over the first weeks, sometimes after a week or two of feeling tired. No human trial has tested it yet.
- SS-31Injection-site redness, itching or welts (very common), and for some, steadier stamina with less post-exertion crash over weeks.
- Studied range
- MOTS-cResearch range: 5–10 mg. Studied in research — not a recommendation.
- SS-31Research range: 2–4 mg. Studied in research — not a recommendation. FDA-approved as Forzinity (elamipretide): 40 mg SubQ once daily, to improve muscle strength in adults and children with Barth syndrome who weigh at least 30 kg (accelerated approval).
- How often
- MOTS-c2–3× weekly
- SS-31Daily
- Half-life
- MOTS-cHours (short)
- SS-31Short (hours)
- Route
- MOTS-cSubQ injection, IM injection
- SS-31SubQ injection
- Typical run
- MOTS-c4–8 week cycles common, 2–3× per year. Common splits: Mon/Thu (2× weekly) or Mon/Wed/Fri (3× weekly). Limited long-term human data — none on continuous dosing.
- SS-31Daily or EOD use. Cycles of 4–8 weeks common; some run continuously. The Forzinity label doses it once daily with no break.
- Evidence
- MOTS-cEmerging: primarily preclinical / limited human data
- SS-31Emerging: primarily preclinical / limited human data
- Common side effects
- MOTS-cInjection site reaction, mild fatigue first week
- SS-31Injection site reaction, nausea, mild headache
Typical run: Community practice — opinions vary. Not a clinical recommendation.
Week by week
Each entry’s cards by day window, as the compound pages show them. Day 1 is the day you start it.
MOTS-c
- Day 1–14 The first two weeks
- Day 14–28 Workouts often feel easier
- Day 28–56 Weeks 4 to 8: check your markers
- Day 56–84 Diminishing returns + cycle point
SS-31
- Day 1–14 A slow, cumulative start
- Day 14–56 Where stamina changes show up
- Day 56–112 Maintenance or cycle-off
Together or one or the other
MOTS-c and SS-31 are a common stack: each lists the other among its common stacks, and they’re together in the Longevity Core stack.
- Longevity Core: Mitochondrial health & cellular-aging stack (MOTS-c, Epitalon and SS-31).
Community · SS-31
Full-spectrum mitochondrial stack
SS-31 protects the mitochondrial membrane itself, MOTS-c tunes metabolic signaling and humanin damps cell-death signaling. Three angles, one organelle. Rationale-based rather than trial-based — no combination data exists.
Questions people ask
How long do MOTS-c and SS-31 last?
The half-life of MOTS-c is hours (short). The half-life of SS-31 is short (hours).
How often are MOTS-c and SS-31 taken?
MOTS-c: 2–3× weekly. Routes: SubQ injection, IM injection. SS-31: daily. Route: SubQ injection.
How are MOTS-c and SS-31 dosed in research?
The research range for MOTS-c is 5–10 mg. Studied in research — not a recommendation. The research range for SS-31 is 2–4 mg. Studied in research — not a recommendation. FDA-approved as Forzinity (elamipretide): 40 mg SubQ once daily, to improve muscle strength in adults and children with Barth syndrome who weigh at least 30 kg (accelerated approval).
What are the common side effects of MOTS-c and SS-31?
For MOTS-c, the library lists: injection site reaction, mild fatigue first week. For SS-31: injection site reaction, nausea, mild headache.
Are MOTS-c and SS-31 taken together?
MOTS-c and SS-31 are a common stack: each lists the other among its common stacks, and they’re together in the Longevity Core stack. SS-31 protects the mitochondrial membrane itself, MOTS-c tunes metabolic signaling and humanin damps cell-death signaling. Three angles, one organelle. Rationale-based rather than trial-based — no combination data exists.
Each one in full
PepVault for iPhone
Track either one in PepVault
Log every dose of MOTS-c or SS-31, with reminders on your schedule. 7 days free on the yearly plan for new subscribers.
