Study room three · ingredients

Reading a Label Line by Line

The front of the bottle is marketing. The back is the evidence. Here is how to read it.

the rules of the label

What INCI tells you

Most cosmetics sold in the European Union, the United Kingdom and many other markets list ingredients using INCI — the International Nomenclature of Cosmetic Ingredients. Under EU Cosmetics Regulation (EC) No 1223/2009, ingredients present above 1% must be listed in descending order of concentration. Below 1%, they may appear in any order. That means the first five or so ingredients make up most of the product, and the long tail of extracts at the end is often present in tiny amounts.

INCI names use Latin for plant ingredients and chemical names for others, so "water" becomes Aqua and shea butter becomes Butyrospermum Parkii Butter. Fragrance appears as Parfum, and the EU requires certain fragrance allergens, such as linalool and limonene, to be named individually above set thresholds.

A quick reading method

Find the base: usually water, then glycerin or another humectant.
Locate the active you are paying for. If it appears after the preservative (phenoxyethanol is typically used at 1% or less), it is present at under 1%.
Check for fragrance and essential oils if your skin is sensitive.
Ignore claims like "clean", "chemical-free" or "clinically proven" without a published study.

Amber glass dropper bottle on a dark surface lit by warm side light

the core actives

Ingredients with real research behind them

Retinoids
Niacinamide
Azelaic acid
Salicylic acid
Glycolic acid
Ceramides
Glycerin
Zinc oxide

Retinoids remain the most studied topical ingredient for photoageing; tretinoin was famously investigated by Albert Kligman and colleagues in the 1980s. Over-the-counter retinol converts to the active form in skin and is gentler but slower.

humectants

Draw water in

Glycerin, hyaluronic acid, urea, panthenol.

emollients

Smooth the surface

Squalane, fatty alcohols, plant oils.

occlusives

Seal it in

Petrolatum, dimethicone, lanolin, beeswax.

a misread

"Alcohol"

Cetyl and cetearyl alcohol are fatty, moisturising alcohols — not drying ethanol.

Comparing common actives

Typical uses and cautions — a summary, not a prescription
Ingredient	Mainly for	Typical OTC strength	Time to see change	Watch for
Retinol	Fine lines, texture, clogged pores	0.1–1%	8–12 weeks	Dryness, peeling; avoid in pregnancy
Niacinamide	Oiliness, redness, uneven tone	2–5%	4–8 weeks	Occasional flushing at high strengths
Azelaic acid	Acne, rosacea bumps, pigmentation	10% (15–20% prescription)	4–12 weeks	Brief tingling
Salicylic acid	Blackheads, oily pores	0.5–2%	4–6 weeks	Dryness; avoid if aspirin-allergic
Glycolic acid	Dullness, rough texture	5–10%	2–6 weeks	Sun sensitivity, stinging
Ceramides	Dryness, barrier repair	Varies	Days–weeks	Rarely irritating

Concentration, formulation and price

Higher percentages are not automatically better. Niacinamide studies showing benefits for oil and redness frequently used 2–5%; products at 10–20% are common but tend to raise the chance of irritation rather than the results. The vehicle matters too: a stable, well-packaged 0.3% retinol in an opaque pump can outperform a poorly stabilised 1% in a clear jar that is exposed to light and air each time it is opened.

Price reflects packaging, marketing and brand positioning far more than ingredient cost. Glycerin, one of the best-evidenced moisturising ingredients, costs very little. Independent cosmetic chemists and dermatology resources such as the American Academy of Dermatology, the British Association of Dermatologists and DermNet are good places to check claims.

Combining ingredients

Many combinations are fine; the real limit is tolerance. Pairing a retinoid and an exfoliating acid on the same night is the most common route to irritation, so alternate them. Niacinamide and vitamin C can be used together despite older advice to the contrary. Sunscreen becomes non-negotiable with retinoids and acids, which make skin more sun-sensitive.

Next: when should a routine stop and a professional take over? See When Skin Asks for a Doctor.