How INCI Order Works
Cosmetic ingredients are listed in descending order by concentration. The first ingredient is present at the highest percentage. The last ingredients are present at trace amounts.
The significance of list position:
Ingredients appearing in the first five to eight positions typically make up 95% to 98% of the product. Everything after the first visible thickener (carbomer, xanthan gum) is usually below 1%.
Active ingredients like retinol, vitamin C and niacinamide need to appear at specific minimum concentrations to produce a measurable effect. If these actives appear at the very end of a long ingredient list, the concentration is likely too low to do anything meaningful.
Key Active Ingredients and Their Effective Concentrations
Vitamin C (L-Ascorbic Acid)
What it does: Antioxidant protection against UV-generated free radicals. Brightens hyperpigmentation. Stimulates collagen synthesis.
Effective concentration: 10% to 20%. Below 10%, the evidence for meaningful efficacy decreases significantly. At 5% and below, the ingredient is present but the measurable effect is minimal.
How to check: L-ascorbic acid should appear within the first four to six ingredients in a vitamin C serum. If you see it listed near the end, the concentration is insufficient for the claimed benefits.
Stable alternatives: Ascorbyl glucoside (gentler, slower), sodium ascorbyl phosphate (more stable, less irritating). These are less potent but more stable in formulas.
Retinol and Retinoids
What it does: Increases cell turnover, reducing the appearance of fine lines, hyperpigmentation and acne. One of the most evidence-supported actives in skincare.
Effective concentration: 0.025% to 1% retinol. 0.025% is a starter dose for sensitive skin. 0.5% to 1% is the range with the strongest efficacy data.
Over-the-counter limit: Retinol up to 0.3% in the EU (cosmetic category). Higher strengths are prescription-only in many countries. Tretinoin (retinoic acid, the active form) requires a prescription in most markets.
Where it appears on the label: Retinol is used at very low percentages so it appears later in ingredient lists. This is normal and does not indicate insufficient concentration; look for it by name rather than position.
Paste your product's ingredient list to get a full breakdown of what each ingredient does, whether concentrations appear effective, any known irritants or allergens and whether the ingredients are compatible with each other. The Ingredient Checker analyses any INCI list instantly.
Check My IngredientsAsk Beauty QuestionsNiacinamide (Vitamin B3)
What it does: Reduces inflammation, minimises pore appearance, regulates sebum, reduces hyperpigmentation, strengthens the skin barrier.
Effective concentration: 2% to 10%. 5% is the most widely studied concentration. At 10%, there is evidence for enhanced sebum regulation.
Compatibility: Pairs well with most other actives. The historical concern about niacinamide and vitamin C is largely unsupported by current research. Niacinamide and retinol work well together and the niacinamide reduces retinol-related irritation.
Hyaluronic Acid
What it does: Attracts and holds water in the skin, providing temporary plumping and hydration. Does not penetrate deeply; works primarily at the skin surface and upper dermis.
Molecular weight matters: High molecular weight HA stays on the skin surface for immediate plumping. Low molecular weight HA penetrates slightly deeper for more sustained hydration. The best HA products contain both.
What it does not do: HA does not permanently increase skin hydration. It requires water to function. Applying it in dry conditions or without sealing with a moisturiser causes it to draw moisture from the deeper skin layers rather than from the environment.
AHAs and BHAs
Glycolic acid (AHA): The smallest AHA molecule; deepest penetration. Exfoliates dead skin cells, brightens and improves texture. Effective at pH 3.5 to 4 and concentrations of 5% to 10%.
Lactic acid (AHA): Gentler than glycolic; larger molecule; better for sensitive skin. Also hydrating. Effective at 5% to 12%.
Salicylic acid (BHA): Oil-soluble; penetrates pores. Best active for blackheads, whiteheads and oily or acne-prone skin. Effective at 0.5% to 2%.
Ceramides
What they do: Ceramides are lipid molecules that naturally form 40% to 50% of the skin barrier. They seal moisture in and protect against environmental damage.
Who needs them most: Anyone with dry, sensitive or eczema-prone skin benefits from ceramide-containing moisturisers. Effective products contain ceramides alongside cholesterol and fatty acids in the correct ratio.
Key names on labels: Ceramide NP, ceramide AP, ceramide EOP, ceramide EOS, ceramide NS. Products containing three or more ceramide types are more closely aligned with the natural skin barrier composition.