LL-37 vs SS-31
Updated October 16, 2026 · Reviewed by the PeptidesDB Editorial team
A data-driven comparison of LL-37 and SS-31 (also searched as SS-31 vs LL-37) — effect profiles, evidence, side effects, and which suits weight loss, muscle, or healing goals.
Verdict
LL-37 centers on healing, while SS-31 leans toward healing. On indexed research, SS-31 is ahead (LL-37: 35 studies, Human evidence; SS-31: 38, Human evidence). Choose by goal — and read the primary studies. This is research information, not medical advice.
Key takeaways
- •LL-37 is strongest for healing; SS-31 for healing.
- •Evidence: LL-37 Human evidence (35 studies) vs SS-31 Human evidence (38).
- •Both are research-use compounds — not FDA-approved.
Effect profiles, overlaid
At a glance
LL-37 vs SS-31: side-by-side
| Metric | LL-37 | SS-31 |
|---|---|---|
| Class | Immune | Metabolic |
| Regulatory status | Research use only | Research use only |
| Evidence grade | Human evidence | Human evidence |
| Studies indexed | 35 | 38 |
| Research level | Well Studied | Preclinical |
| Strongest effect | Healing & recovery | Healing & recovery |
| Healing & recovery | 5.0▲ | 4.0 |
| Muscle & body comp | 0.0 | 2.0▲ |
| Metabolic & appetite | 0.0 | 3.0▲ |
| Neuro & mood | 0.0 | 4.0▲ |
| Sleep & circadian | 0.0 | 1.0▲ |
| Inflammation & immune | 4.0▲ | 3.0 |
| Skin & aesthetics | 2.0▲ | 1.0 |
▲ marks the higher AI-assigned effect score (0–5, describing where the literature concentrates — not clinical efficacy).
Mechanism & pharmacokinetics
| Property | LL-37 | SS-31 |
|---|---|---|
| Mechanism | Disrupts microbial membranes, modulates immune responses | Cardiolipin binding to stabilize mitochondrial membrane |
| Route | — | Subcutaneous injection |
Established pharmacology — curated for well-characterized compounds and AI-summarized otherwise. A blank (—) means no reliable single value is published (half-life figures for some peptides genuinely disagree across sources). Verify against primary sources such as FDA labels and ClinicalTrials.gov.
What is LL-37?
LL-37 is a human cathelicidin antimicrobial peptide that plays a crucial role in the innate immune response. It is produced by various cells, including epithelial cells and neutrophils, and exhibits a broad spectrum of biological activities, including antimicrobial, immunomodulatory, and wound healing properties. LL-37 interacts with a variety of pathogens, including bacteria, viruses, and fungi, contributing to the host's defense mechanisms.
Full LL-37 profile, mechanism & studies →What is SS-31?
SS-31, also known as Elamipretide, is a peptide that has garnered attention for its potential role in mitochondrial protection and its implications in various health conditions, particularly those involving oxidative stress and mitochondrial dysfunction.
Full SS-31 profile, mechanism & studies →Which is better for your goal?
| Goal | Better fit | Why |
|---|---|---|
| Healing | LL-37 | 5.0/5 effect signal |
| Muscle | SS-31 | 2.0/5 effect signal |
| Metabolic | SS-31 | 3.0/5 effect signal |
| Neuro | SS-31 | 4.0/5 effect signal |
| Sleep | SS-31 | 1.0/5 effect signal |
| Inflammation | LL-37 | 4.0/5 effect signal |
| Skin | LL-37 | 2.0/5 effect signal |
Fit reflects community-perceived effect profiles — not head-to-head trials. Read each peptide's studies before deciding.
Can you stack LL-37 and SS-31?
People sometimes combine peptides that target different pathways, but there is little controlled research on this specific pairing and the interactions aren't well characterized. Because neither compound is FDA-approved, we don't publish stacking or dosing protocols here. Any combination should be discussed with a qualified clinician.
LL-37 vs SS-31: side effects
No community-reported effects logged yet.
No community-reported effects logged yet.
Anonymous community reports (count = number of reports), not clinical incidence rates.
What the research says
LL-37 has 35 approved studies indexed (Human evidence), and SS-31 has 38 (Human evidence). The Librarian re-checks PubMed, Europe PMC and ClinicalTrials daily, so these counts move. Open each profile to read the summaries and sources.
Frequently asked questions
Is LL-37 or SS-31 better?
It depends on your goal. LL-37 is strongest for healing; SS-31 for healing. SS-31 has more indexed studies (38). See the goal-by-goal breakdown above.
Is LL-37 or SS-31 better for weight loss?
SS-31 shows the stronger metabolic & appetite profile (3.0/5) in the AI-assigned effect profile — though weight-loss outcomes depend on the individual and the evidence base.
Is LL-37 or SS-31 better for muscle?
SS-31 leads on the muscle & body-composition axis (2.0/5).
Which has more research, LL-37 or SS-31?
LL-37 has 35 approved studies indexed (Human evidence); SS-31 has 38 (Human evidence). Higher counts mean more to read, not proven superiority.
Can you stack LL-37 and SS-31?
Some users combine peptides, but there's little controlled data on this specific pairing, and interactions aren't well characterized. We don't publish stacking protocols for compounds that aren't FDA-approved. Discuss any combination with a qualified clinician.
What are the side effects of LL-37 vs SS-31?
LL-37: no community-reported effects logged yet. SS-31: none logged yet. These are anonymous reports, not incidence rates — see each profile.
Is LL-37 or SS-31 FDA-approved?
LL-37 is a research-use compound and is not FDA-approved. SS-31 is not FDA-approved. Research-use status is not a legal clearance to compound or use in humans.
Is SS-31 better than LL-37?
For healing, SS-31 has the edge; for healing, LL-37 does. Neither is universally "better" — it's goal-dependent, and both should be weighed against their evidence base above.
Comparing related peptides
Regulatory & legal status
LL-37 and SS-31 are research-use compounds and are not FDA-approved for human use. FDA approval and compounding rules for peptides change frequently, and research-use status is not a legal clearance for human use. The FDA does not review compounded drugs for safety, effectiveness, or quality. Verify current status with primary sources before acting. Last reviewed October 16, 2026.