Peptides, explainedPeptides are small chains of the building blocks used in proteins. Their names identify ingredients, not quality scores. Open an explanation to learn what each one means.
A Medik8Carnosine A peptide name recorded on a manufacturer’s cosmetic ingredient list. The name identifies an ingredient, not a predicted result.
A peptide name recorded on a manufacturer’s cosmetic ingredient list. The name identifies an ingredient, not a predicted result.
Type of support: Label information
What it is An exact ingredient name from the linked label. Its number is part of its identity, not a quality score.
Why it is used The manufacturer includes this ingredient in a peptide skincare formula. The label alone does not show what this ingredient contributes by itself.
What the evidence means The recorded evidence is label information. No independent test of this ingredient in these finished serums is established here.
Precautions and possible reactions A label entry cannot tell us how often this ingredient causes a reaction. Follow the complete product directions; irritation can involve other ingredients too.
Cosmetics can cause irritation or allergic reactions. Check the full ingredient list and follow product directions.
What this means for your comparison Use this name to recognize the ingredient across labels. Judge the finished product with its directions and evidence, rather than its peptide count.
Sources checked 2026-10-19 . Ingredient information is separate from testing a finished serum.
Read the full ingredient guide Acetyl Hexapeptide-8 A peptide studied for the appearance of expression lines around the eyes.
A peptide studied for the appearance of expression lines around the eyes.
Type of support: Ingredient study
Editorial draft · Qualified scientific review pending.
What it is A synthetic peptide investigated under the name Argireline. The study concerns a specific preparation, not every product listing this ingredient.
Why it is used Studied as a cosmetic ingredient for reducing the appearance of eye-area lines.
What the evidence means A four-week randomized placebo-controlled trial enrolled 60 Chinese participants (3:1 allocation) and reported improved eye-area wrinkle measures. The inspected abstract does not establish results for the retail serums here or long-term benefit. A 24-hour laboratory skin-penetration study is a different kind of evidence, not a clinical efficacy trial.
Precautions and possible reactions The 2025 safety panel concluded safe cosmetic use up to 0.005%; above that, it found insufficient data to determine safety. This is not evidence of harm above that amount. The pure-peptide concentrations in these compared serums are not verified, so this assessment cannot certify either bottle. A commercial blend percentage is not automatically the pure-peptide percentage.
Cosmetics can cause irritation or allergic reactions. Check the full ingredient list and follow product directions.
What this means for your comparison There is human research on a preparation of this ingredient. That is different from a direct test of this serum.
Sources checked 2026-10-20 . Ingredient information is separate from testing a finished serum.
Read the full ingredient guide Palmitoyl Tripeptide-1 A skin-conditioning peptide used in blends marketed for the appearance of wrinkles.
A skin-conditioning peptide used in blends marketed for the appearance of wrinkles.
Type of support: Supplier description
Editorial draft · Qualified scientific review pending.
What it is A peptide with three amino-acid units and an attached fatty-acid part. The added part distinguishes its ingredient name.
Why it is used Croda includes it in Matrixyl 3000, an ingredient blend marketed for wrinkle appearance. This does not confirm a branded blend or its dose in this serum.
What the evidence means The supplier describes a blend, not an independent test of this ingredient alone in The Ordinary serum.
Precautions and possible reactions A safety review addresses reported cosmetic uses, not every possible formula or individual reaction.
Cosmetics can cause irritation or allergic reactions. Check the full ingredient list and follow product directions.
What this means for your comparison A peptide blend’s claims cannot be assigned to this ingredient alone or used to rank these two serums.
Sources checked 2026-10-19 . Ingredient information is separate from testing a finished serum.
Read the full ingredient guide Palmitoyl Tetrapeptide-7 A skin-conditioning peptide used in blends marketed for the appearance of wrinkles.
A skin-conditioning peptide used in blends marketed for the appearance of wrinkles.
Type of support: Supplier description
Editorial draft · Qualified scientific review pending.
What it is A peptide with four amino-acid units and an attached fatty-acid part. The added part distinguishes its ingredient name.
Why it is used Croda includes it in Matrixyl 3000, an ingredient blend marketed for wrinkle appearance. This does not confirm a branded blend or its dose in this serum.
What the evidence means The supplier describes a blend, not an independent test of this ingredient alone in The Ordinary serum.
Precautions and possible reactions A safety review addresses reported cosmetic uses, not every possible formula or individual reaction.
Cosmetics can cause irritation or allergic reactions. Check the full ingredient list and follow product directions.
What this means for your comparison A peptide blend’s claims cannot be assigned to this ingredient alone or used to rank these two serums.
Sources checked 2026-10-19 . Ingredient information is separate from testing a finished serum.
Read the full ingredient guide Palmitoyl Tripeptide-38 A peptide associated with the commercial blend name Matrixyl synthe’6.
A peptide associated with the commercial blend name Matrixyl synthe’6.
Type of support: Label information
Editorial draft · Qualified scientific review pending.
What it is This ingredient name appears on the recorded Matrixyl, Multi-Peptide + HA and Power Peptides labels.
Why it is used The brands place it in blends marketed for the appearance of lines. This does not isolate its contribution to a finished serum.
What the evidence means The recorded support is manufacturer information about labels and ingredient systems. It does not establish how well this ingredient alone works in these finished serums.
Precautions and possible reactions An ingredient-specific side-effect rate is not established by these sources. Check the complete product label and follow its current instructions.
Cosmetics can cause irritation or allergic reactions. Check the full ingredient list and follow product directions.
What this means for your comparison Recognize the exact ingredient name, then consider the whole product. Neither its number nor a blend percentage tells us which serum will work better for you.
Sources checked 2026-10-19 . Ingredient information is separate from testing a finished serum.
Read the full ingredient guide Palmitoyl Pentapeptide-4 A peptide name recorded on a manufacturer’s cosmetic ingredient list. The name identifies an ingredient, not a predicted result.
A peptide name recorded on a manufacturer’s cosmetic ingredient list. The name identifies an ingredient, not a predicted result.
Type of support: Label information
What it is An exact ingredient name from the linked label. Its number is part of its identity, not a quality score.
Why it is used The manufacturer includes this ingredient in a peptide skincare formula. The label alone does not show what this ingredient contributes by itself.
What the evidence means The recorded evidence is label information. No independent test of this ingredient in these finished serums is established here.
Precautions and possible reactions A label entry cannot tell us how often this ingredient causes a reaction. Follow the complete product directions; irritation can involve other ingredients too.
Cosmetics can cause irritation or allergic reactions. Check the full ingredient list and follow product directions.
What this means for your comparison Use this name to recognize the ingredient across labels. Judge the finished product with its directions and evidence, rather than its peptide count.
Sources checked 2026-10-19 . Ingredient information is separate from testing a finished serum.
Read the full ingredient guide Tetrapeptide-21 A peptide identified by the brand as part of TEGO PEP 4-17.
A peptide identified by the brand as part of TEGO PEP 4-17.
Type of support: Label information
What it is A distinct peptide listed on the Power Peptides label. The number 21 is an identifier, not a strength score.
Why it is used Geek & Gorgeous describes it within a blend marketed for the appearance of skin firmness.
What the evidence means The recorded support is manufacturer information about labels and ingredient systems. It does not establish how well this ingredient alone works in these finished serums.
Precautions and possible reactions An ingredient-specific side-effect rate is not established by these sources. Check the complete product label and follow its current instructions.
Cosmetics can cause irritation or allergic reactions. Check the full ingredient list and follow product directions.
What this means for your comparison Recognize the exact ingredient name, then consider the whole product. Neither its number nor a blend percentage tells us which serum will work better for you.
Sources checked 2026-10-19 . Ingredient information is separate from testing a finished serum.
Read the full ingredient guide Pentapeptide-18 A peptide name recorded on a manufacturer’s cosmetic ingredient list. The name identifies an ingredient, not a predicted result.
A peptide name recorded on a manufacturer’s cosmetic ingredient list. The name identifies an ingredient, not a predicted result.
Type of support: Label information
What it is An exact ingredient name from the linked label. Its number is part of its identity, not a quality score.
Why it is used The manufacturer includes this ingredient in a peptide skincare formula. The label alone does not show what this ingredient contributes by itself.
What the evidence means The recorded evidence is label information. No independent test of this ingredient in these finished serums is established here.
Precautions and possible reactions A label entry cannot tell us how often this ingredient causes a reaction. Follow the complete product directions; irritation can involve other ingredients too.
Cosmetics can cause irritation or allergic reactions. Check the full ingredient list and follow product directions.
What this means for your comparison Use this name to recognize the ingredient across labels. Judge the finished product with its directions and evidence, rather than its peptide count.
Sources checked 2026-10-19 . Ingredient information is separate from testing a finished serum.
Read the full ingredient guide Acetyl Tetrapeptide-5 A peptide name recorded on a manufacturer’s cosmetic ingredient list. The name identifies an ingredient, not a predicted result.
A peptide name recorded on a manufacturer’s cosmetic ingredient list. The name identifies an ingredient, not a predicted result.
Type of support: Label information
What it is An exact ingredient name from the linked label. Its number is part of its identity, not a quality score.
Why it is used The manufacturer includes this ingredient in a peptide skincare formula. The label alone does not show what this ingredient contributes by itself.
What the evidence means The recorded evidence is label information. No independent test of this ingredient in these finished serums is established here.
Precautions and possible reactions A label entry cannot tell us how often this ingredient causes a reaction. Follow the complete product directions; irritation can involve other ingredients too.
Cosmetics can cause irritation or allergic reactions. Check the full ingredient list and follow product directions.
What this means for your comparison Use this name to recognize the ingredient across labels. Judge the finished product with its directions and evidence, rather than its peptide count.
Sources checked 2026-10-19 . Ingredient information is separate from testing a finished serum.
Read the full ingredient guide Copper Palmitoyl Heptapeptide-14 A copper-containing peptide with a different name from Copper Tripeptide-1.
A copper-containing peptide with a different name from Copper Tripeptide-1.
Type of support: Label information
What it is The Power Peptides label lists this exact name separately from Heptapeptide-15 Palmitate.
Why it is used The brand describes it as part of its X50 Antiaging ingredient system. Its product description does not independently prove better delivery or visible outcomes.
What the evidence means The recorded support is manufacturer information about labels and ingredient systems. It does not establish how well this ingredient alone works in these finished serums.
Precautions and possible reactions An ingredient-specific side-effect rate is not established by these sources. Check the complete product label and follow its current instructions.
Cosmetics can cause irritation or allergic reactions. Check the full ingredient list and follow product directions.
What this means for your comparison Recognize the exact ingredient name, then consider the whole product. Neither its number nor a blend percentage tells us which serum will work better for you.
Sources checked 2026-10-19 . Ingredient information is separate from testing a finished serum.
Read the full ingredient guide Palmitoyl sh-Hexapeptide-13 Serine SP Amide A peptide name recorded on a manufacturer’s cosmetic ingredient list. The name identifies an ingredient, not a predicted result.
A peptide name recorded on a manufacturer’s cosmetic ingredient list. The name identifies an ingredient, not a predicted result.
Type of support: Label information
What it is An exact ingredient name from the linked label. Its number is part of its identity, not a quality score.
Why it is used The manufacturer includes this ingredient in a peptide skincare formula. The label alone does not show what this ingredient contributes by itself.
What the evidence means The recorded evidence is label information. No independent test of this ingredient in these finished serums is established here.
Precautions and possible reactions A label entry cannot tell us how often this ingredient causes a reaction. Follow the complete product directions; irritation can involve other ingredients too.
Cosmetics can cause irritation or allergic reactions. Check the full ingredient list and follow product directions.
What this means for your comparison Use this name to recognize the ingredient across labels. Judge the finished product with its directions and evidence, rather than its peptide count.
Sources checked 2026-10-19 . Ingredient information is separate from testing a finished serum.
Read the full ingredient guide Selected label peptides, not the complete INCI list. Other peptides and non-peptide ingredients may be omitted. See the manufacturer for the full formula. B The OrdinaryAcetyl Hexapeptide-8 A peptide studied for the appearance of expression lines around the eyes.
A peptide studied for the appearance of expression lines around the eyes.
Type of support: Ingredient study
Editorial draft · Qualified scientific review pending.
What it is A synthetic peptide investigated under the name Argireline. The study concerns a specific preparation, not every product listing this ingredient.
Why it is used Studied as a cosmetic ingredient for reducing the appearance of eye-area lines.
What the evidence means A four-week randomized placebo-controlled trial enrolled 60 Chinese participants (3:1 allocation) and reported improved eye-area wrinkle measures. The inspected abstract does not establish results for the retail serums here or long-term benefit. A 24-hour laboratory skin-penetration study is a different kind of evidence, not a clinical efficacy trial.
Precautions and possible reactions The 2025 safety panel concluded safe cosmetic use up to 0.005%; above that, it found insufficient data to determine safety. This is not evidence of harm above that amount. The pure-peptide concentrations in these compared serums are not verified, so this assessment cannot certify either bottle. A commercial blend percentage is not automatically the pure-peptide percentage.
Cosmetics can cause irritation or allergic reactions. Check the full ingredient list and follow product directions.
What this means for your comparison There is human research on a preparation of this ingredient. That is different from a direct test of this serum.
Sources checked 2026-10-20 . Ingredient information is separate from testing a finished serum.
Read the full ingredient guide Palmitoyl Tripeptide-1 A skin-conditioning peptide used in blends marketed for the appearance of wrinkles.
A skin-conditioning peptide used in blends marketed for the appearance of wrinkles.
Type of support: Supplier description
Editorial draft · Qualified scientific review pending.
What it is A peptide with three amino-acid units and an attached fatty-acid part. The added part distinguishes its ingredient name.
Why it is used Croda includes it in Matrixyl 3000, an ingredient blend marketed for wrinkle appearance. This does not confirm a branded blend or its dose in this serum.
What the evidence means The supplier describes a blend, not an independent test of this ingredient alone in The Ordinary serum.
Precautions and possible reactions A safety review addresses reported cosmetic uses, not every possible formula or individual reaction.
Cosmetics can cause irritation or allergic reactions. Check the full ingredient list and follow product directions.
What this means for your comparison A peptide blend’s claims cannot be assigned to this ingredient alone or used to rank these two serums.
Sources checked 2026-10-19 . Ingredient information is separate from testing a finished serum.
Read the full ingredient guide Palmitoyl Tetrapeptide-7 A skin-conditioning peptide used in blends marketed for the appearance of wrinkles.
A skin-conditioning peptide used in blends marketed for the appearance of wrinkles.
Type of support: Supplier description
Editorial draft · Qualified scientific review pending.
What it is A peptide with four amino-acid units and an attached fatty-acid part. The added part distinguishes its ingredient name.
Why it is used Croda includes it in Matrixyl 3000, an ingredient blend marketed for wrinkle appearance. This does not confirm a branded blend or its dose in this serum.
What the evidence means The supplier describes a blend, not an independent test of this ingredient alone in The Ordinary serum.
Precautions and possible reactions A safety review addresses reported cosmetic uses, not every possible formula or individual reaction.
Cosmetics can cause irritation or allergic reactions. Check the full ingredient list and follow product directions.
What this means for your comparison A peptide blend’s claims cannot be assigned to this ingredient alone or used to rank these two serums.
Sources checked 2026-10-19 . Ingredient information is separate from testing a finished serum.
Read the full ingredient guide Palmitoyl Tripeptide-38 A peptide associated with the commercial blend name Matrixyl synthe’6.
A peptide associated with the commercial blend name Matrixyl synthe’6.
Type of support: Label information
Editorial draft · Qualified scientific review pending.
What it is This ingredient name appears on the recorded Matrixyl, Multi-Peptide + HA and Power Peptides labels.
Why it is used The brands place it in blends marketed for the appearance of lines. This does not isolate its contribution to a finished serum.
What the evidence means The recorded support is manufacturer information about labels and ingredient systems. It does not establish how well this ingredient alone works in these finished serums.
Precautions and possible reactions An ingredient-specific side-effect rate is not established by these sources. Check the complete product label and follow its current instructions.
Cosmetics can cause irritation or allergic reactions. Check the full ingredient list and follow product directions.
What this means for your comparison Recognize the exact ingredient name, then consider the whole product. Neither its number nor a blend percentage tells us which serum will work better for you.
Sources checked 2026-10-19 . Ingredient information is separate from testing a finished serum.
Read the full ingredient guide Selected label peptides, not the complete INCI list. Other peptides and non-peptide ingredients may be omitted. See the manufacturer for the full formula. 
