How we score products

The score

The Selenssa Score runs from 0 to 100. It is 90% formulation — the ingredient list assessed against current safety evidence and regulatory positions — and 10% real-world effectiveness drawn from user feedback and consolidated customer reviews.

We use INCI — the International Nomenclature of Cosmetic Ingredients — because it is the standard language manufacturers use to list what is actually in a product. Wherever possible we source this list directly from the brand or retailer, then check each entry against current research and regulatory guidance.

The band is a consistent, mechanical output of the methodology, not an opinion of the brand. The same ingredient list will always produce the same score, regardless of how the product was discovered.

Endocrine concern

30 points

Contamination risk

20 points

Irritation & sensitisation

15 points

Formulation quality

15 points

Environmental impact

10 points

Transparency of labelling

10 points

Bands

• 80–100 · Safe / Clean

  Strong ingredient profile with low overall concern.

• 60–79 · Caution

  Generally acceptable, with one or more ingredients worth considering.

• 0–59 · Avoid / High Concern

  Concerns significant enough that we suggest considering an alternative.

A product containing a red-flag ingredient — for example a formaldehyde releaser or a banned UV filter — is classified Avoid / High Concern regardless of its numeric score, so one serious concern cannot be diluted by many low-concern ingredients. A product whose only flagged ingredients are allergens is capped at Caution rather than Avoid: sensitisation matters if you react easily, but it is not the same class of concern.

Hazard categories

Alongside the single score, every product carries three category-level ratings so a fragrance-heavy moisturiser is not read the same way as one containing a cancer-linked preservative. Each rating is a lookup against a classification list, not a judgement:

• Allergy & sensitisation — the 26 declarable fragrance allergens under EU Cosmetics Regulation Annex III, undisclosed parfum, allergen-rich essential oils and established contact sensitisers such as methylisothiazolinone.
• Endocrine disruption — ingredients on EU endocrine-disruptor priority lists or restricted by the SCCS on hormonal grounds: certain UV filters (homosalate, oxybenzone, octinoxate), longer-chain parabens, phthalates and cyclic silicones.
• Cancer-linked — ingredients with an IARC classification or a California Prop 65 listing, and recognised contaminant risks such as 1,4-dioxane in ethoxylates or nitrosamine formation from ethanolamines.

Each category is rated none, low, moderate or high from the worst-rated ingredient present, with several separate allergens compounding to a high allergen load. Where we differ from hazard-only databases: we weight by exposure — product type, leave-on versus rinse-off and likely concentration from ingredient order — so the same substance can carry a different weight in a rinse-off cleanser than in a leave-on serum. That is also why our ratings are not directly comparable with EWG's.

Verified vs estimated scores

A score is only shown as confident when we hold the manufacturer's published INCI for that exact product. Verified products display ✓ Verified against manufacturer INCI with a solid score and a "Last verified" date. Everything else displays a Pending verification badge and a tilde — for example ~92 · Safe/Clean (estimated) — with a dotted, muted treatment so it is visually distinct.

We haven't yet confirmed those ingredient lists against the manufacturer's official label. The score shown is an estimate and may change once verified.

Source records and audit trail

No score change goes live without a source record attached. Each record stores the exact page the ingredient list came from, the source type, the time and process that retrieved it, the ingredient text verbatim, and a saved copy of the page at the time of fetch.

Every change to a score is written to an append-only audit log — old and new score, old and new band, the reason, the source record and who approved it. That history is shown publicly under "Where this score comes from" on each product page.

Corrections and disputes

Brands, retailers and shoppers can flag anything they believe is wrong. Every report is logged with a reference and tracked through to resolution.

Ingredient ratings and versions

Hazard ratings are held against the ingredient itself, not copied into each product. Each ingredient carries the authority behind its rating, the reasoning, a version number that increments whenever the rating changes, and a review date — quarterly by default, monthly for ingredients under active scientific or regulatory debate. When a rating changes, every product containing that ingredient is flagged for rescoring rather than updated silently. Browse ingredient ratings →

Methodology versions

Separate from individual ingredient ratings, the scoring rules and thresholds themselves are versioned. Each change is dated and logged here.

• v1.1 · effective 2026-08-29

  Introduced the versioned ingredient registry: hazard ratings are held per INCI ingredient with source, review cadence and an append-only change log. Ingredient rating changes now flag affected products for rescoring rather than updating scores silently.

• v1.0 · effective 2026-06-01

  Initial published methodology: 90% formulation / 10% real-world effectiveness, bands Safe 80-100, Caution 60-79, Avoid 0-59, red-flag ingredient override.