Why Skincare Concentrations Matter (And Why Most Brands Hide Them)

An ingredient is not a dose. The presence of a compound on an INCI list confirms it exists in the formula — it says nothing about whether enough is present to do what published research says it does. This gap between “ingredient present” and “ingredient at effective concentration” is the largest unaddressed information asymmetry in skincare.

Every active ingredient has a concentration threshold below which it does not produce meaningful biological effects. This threshold varies by ingredient, but the principle is universal:

• Retinol shows effects in published studies at 0.025–1.0%. At 0.001%, it is present but functionally inert.

• Niacinamide demonstrates barrier repair and sebum regulation at 2–5%. At 0.1%, it is a label ingredient.

• GHK-Cu supports collagen synthesis in clinical formulations at 1–3% (Pickart et al., 2015, PMC4508379). At 0.01%, it faces the same skin barrier but with 100x less starting material.

• Vitamin C (L-Ascorbic Acid) requires 8–20% for antioxidant photoprotection (Pinnell et al., 2001). Below 8%, the effects diminish significantly.

A product can legally list all of these ingredients on its label at 0.001% each. The label looks impressive. The formulation is not.

INCI labeling rules — the international standard for cosmetic ingredient lists — require ingredients above 1% to be listed in descending concentration order. Below 1%, any order is permitted. Concentration disclosure is not required at any level.

This regulatory framework was designed for safety (ensuring consumers can identify allergens and irritants), not for efficacy evaluation. It tells you what is in the product. It does not tell you how much.

The result is a market where the ingredient list functions as a marketing tool rather than a formulation disclosure. Brands compete on how many recognizable active ingredients appear on the label, not on the concentration of any single one.

The reasons are varied, and not all are cynical.

Active ingredients at effective concentrations cost more. GHK-Cu at 1% requires 100x more peptide than GHK-Cu at 0.01%. Retinol at 0.5% requires significantly more investment in stability technology than retinol at 0.01%. Disclosing a low concentration invites unfavorable comparison to products (or published research) using higher amounts.

Achieving stable, effective concentrations of some ingredients — particularly peptides in lipid-based systems or ascorbic acid at high percentages — requires genuine formulation expertise. Some brands cannot achieve the concentrations that research supports and therefore have no incentive to disclose what they can achieve.

If no one in your category discloses, there is no competitive pressure to start. The first brand to disclose forces the conversation, which is uncomfortable for brands that have been marketing on ingredient presence rather than concentration.

Some brands worry about disclosing a concentration they cannot consistently maintain. A stated “1% GHK-Cu” creates an implicit accuracy claim. If batch testing reveals variation between 0.8% and 1.2%, some brands prefer the ambiguity of non-disclosure to the accountability of a stated number.

This concern is legitimate. It is also solvable — through third-party testing, batch-specific Certificates of Analysis, and stated tolerances (e.g., “1% ± 0.1%”). The supplement industry has operated this way for decades.

Without concentration data, product evaluation reduces to:

• Brand reputation. Does this brand seem trustworthy? (Subjective.)

• Price as proxy. More expensive probably means better ingredients. (Unreliable — packaging, marketing, and margin strategy affect price independent of formulation.)

• Marketing language. “Potent,” “concentrated,” “advanced formula.” (Meaningless without numbers.)

• Before/after photos. (Uncontrolled, selected for favorable results, not comparable across products.)

None of these replace what a stated concentration with third-party verification provides: a data point you can compare to published research.

Published skincare research uses specific concentrations. When you read that “GHK-Cu stimulates collagen synthesis” (Pickart & Margolina, 2018, PMC6073405), that finding was generated at a specific concentration. When a brand cites that research but uses an undisclosed (and potentially much lower) concentration, they are borrowing credibility from research they may not be replicating.

This is not hypothetical. It is the standard practice across the industry.

Minimum: Stated percentage for each active ingredient (e.g., “1% GHK-Cu,” “0.05% Methylene Blue”).

Better: Absolute amount per container (e.g., “567mg GHK-Cu per 2oz jar”). This eliminates ambiguity about what “1%” means relative to total product weight.

Best: Stated concentration + third-party Certificate of Analysis (CoA) confirming the stated amount matches what is in the product. Batch-specific CoAs available to customers.

The supplement industry norm is “better” to “best.” The skincare industry norm is “none of the above.”

When a brand does not disclose concentrations, these inference tools can help — though none replaces actual data.

Effective concentrations of active ingredients increase formulation cost. A 2oz product priced at $15 with five listed peptides is unlikely to contain meaningful concentrations of any of them — the raw ingredient cost alone for effective peptide concentrations would approach or exceed the retail price.

Fewer ingredients means more formulation room per ingredient. A product with 8 ingredients and one declared active has more space for that active than a product with 30 ingredients and six declared actives.

Ask: “What is the exact concentration of [active ingredient] in this product?” The response tells you more than the label:

• Specific number with confidence → Good sign

• “We use an effective concentration” → Non-answer

• “That’s proprietary” → The concentration may not be worth disclosing

• No response → Draw your own conclusion

Does the product format make sense for the ingredient? A hydrophilic peptide in an anhydrous (water-free) formula requires encapsulation technology. If the brand does not mention how they solved this formulation challenge, they may not have solved it — meaning the peptide may be poorly dispersed and largely non-functional.

A small number do, typically in the active ingredient or clinical skincare space. The Ordinary publishes concentrations for many products. Some prescription-adjacent brands disclose retinoid percentages. In the GHK-Cu tallow category specifically, concentration disclosure is rare.

No. Each ingredient has an effective range — a minimum threshold for activity and a maximum beyond which side effects increase without proportional efficacy gains. GHK-Cu’s research-supported range is 1–3%. Retinol can cause irritation above 1% for many users. The goal is evidence-supported concentration, not maximum concentration.

FDA cosmetic regulations focus on safety (ingredient identification, allergen labeling) rather than efficacy validation. Cosmetics are not drugs — they are not required to prove they work, only that they are safe. Concentration disclosure requirements would shift the regulatory framework toward efficacy claims, which would be a fundamental change in how cosmetics are regulated.