How to actually read a hair care ingredient label — the INCI system, what the order means, what to avoid, and why "natural" means nothing.

Focus on the first five ingredients, as these make up the majority of the product. In a shampoo, the first ingredient is almost always water (Aqua) or — in better-formulated products — a botanical hydrosol. The second and third are typically the surfactant system. The fourth and fifth begin the conditioning or active layer. Ingredients listed after the first five are typically present at under 1% individually. An impressive-sounding botanical listed as ingredient 18 out of 20 is present at trace concentration — it is on the label, but it is not meaningfully active in the formula.

INCI names are based on Latin botanical names (Camellia sinensis for green tea, Lavandula angustifolia for lavender), chemical names (Sodium Lauryl Sulfate for SLS), or IUPAC names for synthetic compounds. The standardisation means the same ingredient has the same name on every product globally — which makes pattern recognition learnable. Once you know that anything ending in "-glucoside" is a gentle sugar-derived surfactant, that "-siloxane" or "-cone" indicates a silicone, and that "PEG-" indicates a polyethylene glycol compound, you can scan a list in seconds.

Ingredients present at below 1% concentration can be listed in any order after the 1%+ ingredients. Preservatives, fragrance, and colourants are typically in this section. This is why a preservative like phenoxyethanol can appear anywhere in the lower half of the list — its position below the 1% threshold doesn't indicate it's less than the ingredient above it. It is, however, a reliable signal that anything listed after preservatives is typically at trace concentration.

Sodium Lauryl Sulfate (SLS) and Sodium Laureth Sulfate (SLES) are highly effective surfactants — they are also strongly alkaline and strip the scalp's acid mantle, removing beneficial lipids and microbiome alongside the impurities they're cleaning. Sulfates are powerful cleansing agents that remove oils and dirt from hair — but they can also strip away natural oils, causing dryness and irritation. For people with healthy hair and scalp who aren't managing AGA or scalp conditions, sulfates are not dangerous. For people managing AGA, seborrhoeic dermatitis, or scalp sensitivity, the pH disruption from sulfates adds inflammatory substrate to an already-compromised environment. Glucoside alternatives provide effective cleansing at a compatible pH.

Parabens (Methylparaben, Ethylparaben, Propylparaben, Butylparaben) are effective preservatives that have been in cosmetics for decades. The concern: some parabens — particularly propylparaben and butylparaben — have been shown to weakly mimic estrogen in in vitro studies. Regulatory bodies (EU, FDA) currently consider them safe at cosmetic-use concentrations. The honest position: the evidence of harm at typical cosmetic concentrations is not definitive, but the precautionary principle is reasonable given the availability of effective alternatives. The series rule: for people managing PCOS or hormonal hair loss where estrogen-androgen balance is already disrupted, avoiding additional potential endocrine-disrupting compounds is a rational precaution even without definitive harm evidence.

Silicones (Dimethicone, Cyclopentasiloxane, Amodimethicone — anything ending in "-cone," "-conol," "-siloxane") coat the hair shaft to provide slip, shine, and manageability. They are not dangerous. The issue for scalp health specifically: silicones may build up on the hair and scalp, clogging follicles and potentially creating an environment that traps sebum and impedes product penetration. Water-soluble silicones (typically ending in PEG-modified silicones) rinse out more easily. Non-water-soluble silicones (Dimethicone, pure Cyclopentasiloxane) require sulfate cleansers to remove — which is the cycle: silicone buildup requires aggressive cleansing, which strips the scalp, which requires more conditioning, which adds more silicone. For people managing scalp conditions, the simpler the formula the better.

"Fragrance" or "Parfum" is a single INCI term that can represent dozens of undisclosed individual chemical compounds. Fragrance is a vague term that can legally hide a blend of hundreds of undisclosed chemicals — it can also hide phthalates. The August 3 trichodynia article noted that fragrance compounds are the most common cause of allergic contact dermatitis from cosmetics. Products labelled "fragrance-free" contain no fragrance compounds of any kind — the label "unscented" may contain masking fragrances that are still fragrance compounds. For fragrance-reactive skin or scalp, "fragrance-free" is the only reliable claim.

Several preservatives release small amounts of formaldehyde (a known carcinogen at high exposures) as part of their antimicrobial mechanism: DMDM Hydantoin, Imidazolidinyl Urea, Diazolidinyl Urea, Quaternium-15, Bronopol (2-Bromo-2-Nitropropane-1,3-Diol). The concentrations at which they release formaldehyde in cosmetics are far below industrial exposure levels, and their use is legal in the US. However, they are restricted or banned in the EU cosmetics regulation at standard use concentrations, and they are the primary preservative class that cleaner alternatives (Leucidal, phenoxyethanol, potassium sorbate) are designed to replace.