Also: Decorinyl (Lipotec trade name, now Lubrizol) · decorin-mimetic tetrapeptide (INCI calls it a tripeptide plus citrulline)
SupplementTopical
Decorin-mimic peptide meant to tidy collagen fibres; one tiny randomised trial, no user reports.
Safety tier
Caution
strict bar
Positive
3/10
researcher estimate
Per month
≈ €4–27
estimate
Rank
#22
of 23 supplements
At a glance
Access
Supplement
TopicalFelt in 2.9 weeks
15 min1 h6 h1 day1 week1 month
Builds over days or weeks of regular use rather than with each dose.
Best effects
Claimed: smoother, suppler skin from more uniform collagen fibres (supplier in-vitro data) · measured: less skin-surface roughness than a peptide-free cream at day 20 in a small trial
Downsides
No identifiable user outcomes · rarely disclosed at a known concentration
Typical use
Finished products at supplier-recommended levels (the trade product is a dilute solution), once or twice daily.
Stacked with
Stacked with
Argireline: Tested together in the only trial; no synergy found. · Matrixyl: Usual neighbour in collagen-themed peptide serums.
Safety
Tier by safety barStrict CautionBalanced CleanEvidence only Clean
Seen harm0 of 3
Mechanism0 of 3
Data gap2 of 3
Silent harm0 of 3
Product0 of 3
Never if
known allergy to a product containing it · pregnancy and breastfeeding (no reproductive data, though systemic exposure from a cosmetic is expected to be negligible)
Why each score
Seen harm 0/3
No serious adverse events in the one trial or anywhere in the literature, and no first-hand reports at all; exposure is real but small and untraceable inside multi-peptide products, so the zero is not strong reassurance. Raikou et al., J Cosmet Dermatol 2017 ↗
Mechanism 0/3
A decorin mimic that regulates how collagen fibrils assemble in vitro; decorin itself restrains growth-factor signalling rather than promoting it, and no pathway to serious harm is known. Puig et al., Int J Cosmet Sci 2008 ↗
Data gap 2/3
One small randomised trial (24 volunteers across four arms, about a dozen exposed to the peptide, 60 days); no CIR assessment and no long-term data. Raikou et al., J Cosmet Dermatol 2017 ↗
Silent harm 0/3
The only plausible harms are irritation or contact allergy, noticed at once and gone on stopping.
Product 0/3
Bought as finished over-the-counter serums and creams.
Studies
Evidence
Human RCTs — one small randomised four-arm trial (24 volunteers in total, so about six per arm) found better skin microtopography than a peptide-free cream at day 20; the mechanism comes from the supplier's in-vitro collagen-fibrillogenesis assay. Too small to rely on
Caveat
The idea is collagen quality rather than quantity: aged skin has less working decorin, the protein that keeps collagen fibrils even, and this short peptide copies decorin's collagen-binding sequence. Whether it gets far enough into intact skin to meet dermal collagen is not shown. The one trial is tiny, and Lipotec's suppleness figures are unpublished. No harm signal; the open question is efficacy.
The peptide's chain of amino acids from its start (the N-terminus) to its end, one bead and one letter for each: A alanine, C cysteine, D aspartic acid, E glutamic acid, F phenylalanine, G glycine, H histidine, I isoleucine, K lysine, L leucine, M methionine, N asparagine, P proline, Q glutamine, R arginine, S serine, T threonine, V valine, W tryptophan, Y tyrosine. A modification such as an N-acetyl cap or a C-terminal amide changes how long it lasts in the body. Length tells related peptides apart, from a two-residue dipeptide like carnosine to a 43-residue protein like thymosin beta-4, and predicts neither effect nor safety.
Report grades
Every first-hand Reddit or X report is graded on its own, from glowing through positive, mixed, nothing and negative to bad reaction, and the bar shows how those grades split. Posts that look vendor-adjacent stay on the peptide's page but are left out of the counts.
GlowingPositiveMixedNothingNegativeBad reaction
% positive
The share of a peptide's graded Reddit and X reports that are glowing or positive, vendor-adjacent posts left out. A peptide with few reports is pulled toward the average of all reports, as if it had eight average ones besides its own, so two glowing posts cannot top the list. Peptides rank by this figure, those with no graded report yet after those with one, and Avoid ones after every other entry.
Researcher estimate
No first-hand report of this peptide has been graded yet, so the figure is the researchers' own rating out of 10 from what they read about it. It ranks after every peptide with graded reports until its own arrive.
Safety tier
Each peptide is tiered Clean, Caution or Avoid from its five risk axes under the chosen safety bar. An Avoid peptide carries a real risk of harm, a plausible route to serious harm rather than mere unpleasantness, so it stays listed with the reason but ranks behind every other entry, however good its reviews.
Safety bar
The safety bar sets how much risk it takes to rate a peptide Avoid. Strict: out on any serious mechanism with little human data, or any documented serious harm. Balanced: out on documented serious harm (unless it is obvious, reversible and from a regulated product), or a serious mechanism whose harm would be silent with no human data at all. Evidence only: out only on documented serious harm in humans that is lasting, delayed or from grey-market product.
Seen harm
Documented serious adverse events in humans, from 0 for none despite real exposure to 3 for deaths or several well-documented serious harms. Serious means a hospital or emergency visit or harm lasting weeks, so a headache or a bad night does not count.
Mechanism
A plausible biological route to serious harm at the doses people use, such as growth-factor signalling, hormone-axis suppression, heart or blood-pressure effects or immune activation. It runs from 0 when none is known to 3 when a dangerous pathway has been shown in living animals.
Data gap
How little human safety data exists for the molecule actually sold, from 0 for an approved drug with large trials and years of use to 3 for no human safety data at all. A modified analogue does not inherit its parent's trials.
Silent harm
Whether the feared harm would show quickly or stay hidden, from 0 when it is obvious and goes on stopping to 3 when it is silent and delayed, like tumour promotion or slow organ damage. User reports cannot reveal a harm that takes years to appear, so a high score here limits what good reviews can tell you.
Product
The risk of what people actually buy, from 0 for a regulated pharmacy or supplement product taken by mouth or on the skin to 3 for a grey-market injectable. In one dataset of 6,441 grey-market samples, 42–71% failed basic quality criteria and 15% carried endotoxin; taken by mouth or in the nose, a pack avoids the injection risks.
Evidence
The strongest kind of study behind the peptide's effects, from an approved drug through human controlled trials and small human studies to animal work or nothing of its own. Animal results often fail to carry over to people.
Access
How people get it: as an approved drug, a compounded prescription, an over-the-counter supplement or from the grey market, where nobody checks the vial. The channel decides both the legal position and the risk of a bad batch.
Price per month
Thirty days of the typical dose, from its low end to its high end, priced at the listing a careful buyer would choose: in stock, from a shop scoring 4 of 5 on trust (third-party tested where no score is set), failing that 3, a pure pack before a blend, a European shop first, then the cheapest per mg. The range is the dose's, not the shops'. A per-dose amount counts once a day unless the dose says otherwise. Prices are in euros at ECB rates of 2026-10-29, before shipping; the shop table keeps each listing's price per mg, per gram for bulk supplements. Where no listing can be priced the researchers' own estimate stands in, and says so.
Dose users report
The middle half of the daily doses stated in at least five first-hand reports, vendor posts left out. Where its middle sits more than twice above or below the declared dose, the month is priced at it as well, since what people take is what they pay for.
Shop trust
Each shop's trust on a 1–5 scale, read from its testing and its reputation: 1 for serious red flags (fabricated COAs, scam reports, impersonation, a closed shop), 2 for no public testing, a new shop or active complaints such as seized parcels, 3 for its own COAs or a short track record, 4 for verified third-party testing or a strong reputation, and 5 for third-party batch reports that name the shop, with years of good independent reputation. A shop without a score counts third-party batch testing as 4, its own COAs as 3 and no public tests as 2.
Best value
Within a category or a goal, a peptide that no other beats on both counts: none is rated more positively for the same or a lower monthly price, and none costs less for the same or a higher rating. The chart joins these into the best-value line; the cheapest of them and the best-rated of them both make it, so the line spans the trade-off from cheap to best. Avoid entries never count, and a peptide needs both a % positive and a price to be compared.
Testing
Whether the shop publishes lab results: third-party tested means an independent lab checks each batch, own COA means the shop's own certificate of analysis, and no public tests means neither. A certificate shows purity, not safety.
Added peptide
Some packs sold under one peptide's name hold a second one, such as 5 mg GHK-Cu in a nasal kit, stated only in the description. Sprayed in the nose or injected it reaches the blood like an injection, so it carries the risk of that route and is tiered as the injectable form, whatever its tier on the skin. A pack whose page gives no contents list may hold more than its name.