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
Talk to your medical provider before starting any protocol. That said, here are the doses most people commonly use — shared for educational purposes so you can have an informed conversation. These peptides are sold for research use only and are not FDA-approved drugs, and this isn't 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.
How can I buy this?
We don't have a verified affiliate source for Pentapeptide-18 yet, so there's no coupon or vendor link here — we won't point you to a seller we haven't vetted. When buying any research-use-only peptide, the single biggest variable is the supply chain: insist on a vendor that publishes third-party Certificates of Analysis (COAs) confirming identity and >99% purity. Working with a peptide-literate clinician is one solid route — see our provider directory — or check back as our verified sources list grows.
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