Pentapeptide-18
What do these badges mean?
Evidence tier
- AHuman-validated — Human trials showing positive results and good safety.
- BAnimal-grade — No human trials yet, but solid animal/preclinical evidence of effect and safety.
- CAnecdotal — No human or animal trials — only anecdotal/observational reports.
- DInsufficient evidence — No or insufficient evidence (encyclopedia only — never recommended by the builder).
Safety light
- 🟢 Green — Only mild, manageable side effects; reasonable safety data.
- 🟡 Yellow — Needs active management, has a meaningful contraindication/interaction, or has thin long-term data.
- 🔴 Red — Risk of a hospital-level event — treat with serious caution.
Browse-only — not on the protocol builder's curated shortlist, so the builder won't recommend it.
What is it?
Pentapeptide-18 (marketed as Leuphasyl) is a neuro-relaxer cosmetic peptide commonly stacked with Argireline (acetyl Hexapeptide-3) and SNAP-8 for claimed synergy, in the same “topical Botox” family as Vialox and Syn-Ake.
What does it do in my body?
Pentapeptide-18 mimics enkephalin to bind opioid receptors on pre-synaptic neurons, reducing calcium influx and catecholamine release — and therefore muscle contraction. This is a different mechanistic route to the same expression-line-softening goal as the SNARE- and receptor-targeting peptides elsewhere in this family.
How can it help me?
- Where the science stands: Emerging: 4 studies, 1 human (non-RCT, confounded by co-formulation with retinol)
The full evidence — every human, animal, and lab study, graded — is one tap away: use the See the deeper science → toggle at the top.
Is it dangerous? What are the side effects?
The human-relevant study (Pawłowska et al., 2024) reported improved tolerability in a retinol + oligopeptide nanocarrier formulation, but that reflects the combined product, not Pentapeptide-18 in isolation. No isolated adverse-effect data was captured. Family-wide read: topical delivery carries a benign safety record.
Regulatory status: Cosmetic-grade OTC topical ingredient — not an FDA-reviewed drug.
Typical dosing
Educational context only — talk to a licensed medical provider before any protocol. What follows describes the doses and schedules most commonly reported in the research and by practitioners, shared so you can have an informed conversation. These compounds are sold for research use only, are not FDA-approved drugs, and this is not medical advice.
What should I avoid combining — and what's synergistic?
Topical-only. Commonly stacked with Argireline and SNAP-8 in commercial serum formulations (claimed synergy). No standalone concentration figure was captured in the source profile.
Where do people source this?
OHM does not sell or handle any compound. Research-use-only material is sold by third-party vendors; our vetting notes and disclosures are on the Where to buy page. If you'd rather have a physician in the loop, see the telehealth option. Whatever the route, the supply chain is the real risk: only consider vendors that publish batch-level third-party Certificates of Analysis.
The relaxer with the most actual human signal in this family — but the one human-relevant study tests it stacked with retinol in a nanocarrier, so it doesn’t isolate the peptide’s own effect. Best-studied on paper, still an honest encyclopedia entry rather than a recommendation.
| Class | Neuromuscular “Botox-like” relaxer — topical cosmetic peptide |
| Mechanism (one line) | Mimics enkephalin → binds opioid receptors on pre-synaptic neurons → reduced calcium influx and catecholamine release → less muscle contraction |
| Evidence base | Emerging: 4 studies, 1 human (non-RCT, confounded by co-formulation with retinol) |
| Safety record | Topical-only; benign safety record (Safety: green) |
| Regulatory status | Cosmetic-grade OTC skincare ingredient, not an FDA-reviewed drug |
What it is
Pentapeptide-18 (marketed as Leuphasyl) is a neuro-relaxer cosmetic peptide commonly stacked with Argireline (acetyl Hexapeptide-3) and SNAP-8 for claimed synergy, in the same “topical Botox” family as Vialox and Syn-Ake.
How it works
Pentapeptide-18 mimics enkephalin to bind opioid receptors on pre-synaptic neurons, reducing calcium influx and catecholamine release — and therefore muscle contraction. This is a different mechanistic route to the same expression-line-softening goal as the SNARE- and receptor-targeting peptides elsewhere in this family.
What the research shows
Public profile grade: Emerging — 4 studies, 1 human (non-RCT). The one human-relevant study is a retinol + oligopeptide nanocarrier cohort reporting reduced sebum and facial wrinkles with improved tolerability (Pawłowska et al., 2024, PMID 39459512); the remaining three are in-vitro/computational (e.g. PMID 39337562, PMID 31937863, both).
Despite that human study, OHM’s internal 0035 categorization pass kept Pentapeptide-18 at Tier D / provisional — the human study tests the peptide combined with retinol in a nanocarrier, so it doesn’t isolate Pentapeptide-18’s own effect.
Honest status: the best-studied of the relaxer family on paper, but the cleanest human data is confounded by co-formulation — genuinely more studied than its siblings, not yet genuinely proven in isolation.
Real-world protocol
Topical-only. Commonly stacked with Argireline and SNAP-8 in commercial serum formulations (claimed synergy). No standalone concentration figure was captured in the source profile.
Side effects & management
The human-relevant study (Pawłowska et al., 2024) reported improved tolerability in a retinol + oligopeptide nanocarrier formulation, but that reflects the combined product, not Pentapeptide-18 in isolation. No isolated adverse-effect data was captured. Family-wide read: topical delivery carries a benign safety record.
Regulatory status
Cosmetic-grade OTC topical ingredient — not an FDA-reviewed drug.
Sources
- (thepeptidelist.com directory, captured 2026-06-07) — profile grade: Emerging, 4 studies, 1 human. Studies cited: Pawłowska et al., 2024, PMID 39459512; PMID 39337562; PMID 31937863.
- OHM tier/safety grading: Tier D / provisional (encyclopedia-only), noting the human study’s retinol co-formulation confound.
- Migrated from
cosmetic-topical-peptides-cluster.md(2026-06-10 cluster build) as part of the cluster-to-standalone-article migration.
Related: Argireline (acetyl Hexapeptide-3) · SNAP-8 · Vialox · Syn-Ake
Sources & references
- (thepeptidelist.com directory, captured 2026-06-07) — profile grade: Emerging, 4 studies, 1 human. Studies cited: Pawłowska et al., 2024, PMID 39459512; PMID 39337562; PMID 31937863.
- OHM tier/safety grading: Tier D / provisional (encyclopedia-only), noting the human study’s retinol co-formulation confound.
- Migrated from
cosmetic-topical-peptides-cluster.md(2026-06-10 cluster build) as part of the cluster-to-standalone-article migration.
Related: Argireline (acetyl Hexapeptide-3) · SNAP-8 · Vialox · Syn-Ake