How to Read Ingredient Labels — INCI Nomenclature, Ordering Rules, and What Manufacturers Hide in Plain Sight

Why Is the Same Chemical Called Three Different Things on Three Different Products?

Sodium lauryl sulfate (SLS) appears on cosmetic labels as “Sodium Lauryl Sulfate” (INCI name), on food labels as “E487” (E-number), and on cleaning products as “lauryl sodium sulfate” or “sodium dodecyl sulfate” (common chemical names). Same molecule, different naming systems, different regulatory frameworks. Understanding ingredient labels requires knowing which naming system the product uses, what the ordering rules mean, and where manufacturers are technically compliant but deliberately misleading.

Naming systems by product category

Product type	Naming system	Governed by	Example (same compound)
Cosmetics/personal care	INCI (International Nomenclature of Cosmetic Ingredients)	EU Regulation 1223/2009, US FDA FPLA	Tocopherol
Food	Common name or E-number	EU Regulation 1169/2011, US FDA 21 CFR	Vitamin E or E307
Household cleaning	Chemical name or trade name	EU CLP Regulation, US CPSC	α-Tocopherol
Pharmaceuticals	INN (International Nonproprietary Name)	WHO INN Programme	Tocopherol
Supplements	Common name	Varies by jurisdiction	Vitamin E

Ingredient ordering rules

Product type	Ordering rule	Threshold for unordered	Practical meaning
Cosmetics (EU/US)	Descending order by weight	Below 1% — any order	First 5 ingredients = ~80% of product
Food (EU)	Descending order by weight	None — all ordered	First 3 ingredients = ~80% of product
Food (US)	Descending order by weight	None — all ordered	Same as EU
Cleaning products	No consistent ordering required	N/A	Cannot determine concentration from order
Supplements	Active ingredients by weight, then other ingredients	None	Active amount in “Supplement Facts”

The 1% line in cosmetics

Everything above 1% concentration must be listed in descending order. Below 1%, ingredients can appear in any order. This creates a useful reading technique:

Ingredient	Typical concentration	Above/below 1% line
Water (Aqua)	60-80%	Above (always first)
Primary surfactant (e.g., SLS)	10-25%	Above
Glycerin	3-10%	Above
Fragrance (Parfum)	0.5-2%	Usually at the 1% line
Preservatives (phenoxyethanol, etc.)	0.5-1%	At or below the 1% line
Active ingredients (niacinamide, retinol, etc.)	0.01-5% (varies widely)	Depends on product
Colorants (CI numbers)	< 0.1%	Below

How to find the 1% line: Look for phenoxyethanol, fragrance (parfum), or common preservatives — they’re typically used at 0.5-1%. Everything after them is below 1%.

Common misdirection techniques

Technique	How it works	Example	How to spot it
Ingredient splitting	Same ingredient listed under multiple names to appear lower	”Sucrose, glucose, fructose, corn syrup” (all sugars)	Group functionally identical ingredients mentally
Marketing name emphasis	Front label highlights one ingredient, actual concentration is < 1%	“Hyaluronic acid serum” with HA listed 15th	Check position in INCI list
”Free from” claims	Lists things NOT in product to imply competitors use them	”Free from parabens, sulfates, silicones”	Doesn’t mean the product is safer
Natural-sounding INCI names	Latin plant names make any ingredient sound natural	”Butyrospermum parkii” = shea butter	INCI names are standardized, not natural/synthetic indicators
Concentration ambiguity	Lists active ingredient without concentration	”Contains vitamin C” (could be 0.01% or 20%)	Look for products that state concentration

Regulatory comparison: label completeness

Requirement	EU	US	Singapore
Full ingredient list required (cosmetics)	Yes	Yes	Yes
Full ingredient list required (food)	Yes	Yes	Yes
Full ingredient list required (cleaning)	Partial (hazardous only)	No (voluntary)	Limited
Allergen highlighting	Yes (bold/separate)	Yes (contains statement)	Yes
Concentration disclosed	No (except SPF, alcohol)	No (except active drugs)	No
INCI naming required	Yes	Yes	Yes

Quick Reference Summary

Reading goal	Technique	What it reveals
Find primary ingredients	Read first 5 INCI names	80% of what you’re buying
Find the 1% line	Look for preservatives/fragrance	Everything after is < 1%
Assess active ingredient amount	Check if it’s above or below 1% line	Whether the active is meaningful or token
Identify hidden sugars	Count all sugar-related names	True sugar content
Assess fragrance safety	Look for specific allergen names after “parfum”	Which of the 26 allergens are present

How to apply this

Use the ingredient-checker tool to evaluate product contents to verify ingredient safety based on the data above.

Start by checking the ingredient list of your products against the reference tables above.

Use the ingredient-checker tool to evaluate specific compounds you find on product labels.

Check concentration levels against the safety thresholds listed in the comparison tables.

Avoid products where the risk indicators from the tables suggest exposure above recommended limits.

Replace flagged items with the safer alternatives identified in the substitution recommendations.

Verify new products against the same criteria before adding them to your routine.

Honest Limitations

• Ingredient lists don’t tell you concentration: You know the first ingredient is the most concentrated, but you don’t know whether it’s 40% or 80%. Two products with identical ingredient lists can have very different formulations.
• “Fragrance” (Parfum) hides dozens of compounds: In the US (and partially in the EU), “fragrance” or “parfum” is a single entry that can represent 50-200 individual chemical compounds. Only the 26 EU-regulated allergens must be individually listed.
• INCI names are not intuitive: “Cetearyl alcohol” sounds concerning but is a fatty alcohol (emollient). “Ascorbic acid” sounds clinical but is vitamin C. Learning INCI takes time, and the naming system was designed for professionals, not consumers.
• Label compliance doesn’t mean label honesty: A product can be fully legally compliant while using ingredient splitting, vague concentration claims, and misleading “free from” marketing. Legal doesn’t mean transparent.
• Online databases may be incomplete: Apps like Yuka, INCI Beauty, or EWG Skin Deep rely on databases that may have outdated or incomplete safety assessments. Use them as starting points, not definitive answers.