"Booster" sounds like a stronger kind of serum. It is a name for a set of directions. A booster is a concentrated liquid, sold to be used alone or mixed into something else. We found no regulatory definition of the word for cosmetics.
This page reads one peptide booster's label and directions in full and explains what mixing does to the numbers.
The label, in order
Paula's Choice Pro-Collagen Multi-Peptide Booster, 0.67 oz, product page read 5 October 2026. The brand describes it as containing "six pro-collagen peptides". The ingredient list on the page has 33 entries:
| Positions | Ingredients |
|---|---|
| 1-9 | Water, glycerin, pentylene glycol, hydrolyzed yeast extract, apple fruit extract, dimethicone, propanediol, 1,2-hexanediol, glyceryl glucoside |
| 10-14 | Palmitoyl tetrapeptide-72 amide, SH-polypeptide-121, palmitoyl dipeptide-5 diaminobutyroyl hydroxythreonine, palmitoyl tripeptide-5, tridecapeptide-1 |
| 15 | Tetradecyl aminobutyroylvalylaminobutyric urea acetate (a modified amino-acid compound) |
| 16-33 | Polyglucuronic acid, sodium hyaluronate, thickeners, plant extract, Bacillus ferment, lecithin, preservatives and pH adjusters |
Five ingredients carry a peptide name, at positions 10 to 14. If the brand counts position 15 as its sixth, all six sit below 1,2-hexanediol, a solvent and preservative booster. US labeling rules (21 CFR 701.3(f)) let ingredients present at 1% or less follow the rest in any order, so a position below the 1% point says nothing about which of two ingredients is larger; reading a peptide ingredient list covers how far a list can be read. The page does not state the peptides' amounts.
The brand's frequently-asked-questions section on the same page says its peptides are at "clinically efficacious levels" and that competitors with more peptides "are likely using levels below the recommended standard (especially if the product's price is below $40)". Neither statement gives a number that can be checked.
What PubMed holds on the five names
Searched 5 October 2026, each as a quoted phrase:
| Ingredient | PubMed records |
|---|---|
| Palmitoyl tripeptide-5 | 4 |
| Palmitoyl dipeptide-5 (any form) | 0 |
| Tridecapeptide-1 | 0 |
| Palmitoyl tetrapeptide-72 | 0 |
| SH-polypeptide-121 | 0 |
Four of the five return nothing under their label names. One of them, SH-polypeptide-121, is not a small peptide at all: our COSRX booster analysis found it is a recombinant collagen fragment of 99,369 daltons. The one with records, palmitoyl tripeptide-5, has its own entry on this site. A label name with no PubMed record is common for newer peptides, as the Rhode Barrier Restore Cream analysis found for three of its four. It means the evidence, if any, sits in supplier files rather than the published literature.
The product page has a "Research" section that lists seven citations by journal, month and page range only, for example a cosmetic science journal, March 2022, and a molecular sciences journal, December 2019. There are no titles or authors, so a reader cannot tell from the page which studies are meant or what they tested.
The page also says the product is "clinically proven" to smooth lines in 15 minutes and firm skin in 4 weeks. It does not say how many people were tested, against what control, or where the results are published.
The directions, and what mixing does
The brand's directions say the product is applied once or twice daily to face, eye area and neck after cleansing, toning and exfoliating, as "a pearl-sized amount alone or add to your favorite serum or non-SPF moisturizer" (the brand's wording), with SPF 30+ afterwards in the daytime.
The "add to" option is what defines a booster, and it has a consequence that is plain arithmetic:
| Mix | Each booster ingredient in the mixture |
|---|---|
| Booster alone | 100% of bottle concentration |
| 1 part booster : 1 part moisturizer | about 50% |
| 1 part booster : 3 parts moisturizer | about 25% |
The brand presents mixing as a convenience. No trial we found has tested a peptide booster mixed into another product, so whether a half-strength peptide mixture does more, less or the same is not known. The base it is mixed into also matters: oils, acids or a different pH may change how stable the peptides are, and no published data address that for this product.
The non-SPF instruction is a real formulation point and not a peptide one: mixing anything into sunscreen changes the film the sunscreen was tested as, and SPF values are measured on the finished sunscreen as sold.
Two products, one word
COSRX sells The 6 Peptide Skin Booster Serum, also using the word. Our ingredient analysis of it found six peptide-class ingredients ranging from 403 to 99,369 daltons, one of them a collagen. Same word, different kind of product: the COSRX bottle is marketed as a serum in its own right.
That is the useful lesson about the word. It tells a buyer how a brand suggests using the product. It says nothing about strength, and only the ingredient list and any published trial can do that.
What this page supports saying
- "Booster" is a marketing name with no defined meaning; it usually signals mix-in directions.
- In the booster read here, the peptides sit at positions 10 to 15 of 33, with no declared amounts, and four of the five peptide names have no PubMed record.
- Mixing divides concentration in proportion to the amount of the other product; no trial has measured what that does to results.
For the broader serum category see peptide serum, and for how long published peptide trials ran before measuring anything, how long peptides take to work.
Sources
- Paula's Choice, Pro-Collagen Multi-Peptide Booster product page (paulaschoice.com/pro-collagen-multi-peptide-booster/3020.html): ingredient list, directions, claims, frequently asked questions and "Research" section, read 2026-10-05.
- PubMed E-utilities searches as tabled, run 2026-10-05, with the
quotedphrasesnotfoundcheck. - 21 CFR 701.3(f), cosmetic ingredient labeling, eCFR text read 2026-10-05.
- This site's ingredient analysis of COSRX The 6 Peptide Skin Booster Serum, as published.