Methodology and sources
Everything on Skinredients is published under the site's name rather than a personal byline. This page explains where the numbers come from, what the checker does with your list, and how we handle mistakes, so you can judge the results yourself.
Where the ratings come from
The checker currently holds 230 ingredients with 306 individual ratings. Every rating was transcribed from the tables of a primary, peer-reviewed study. For each one we record the study, the test model (rabbit ear or human), the concentration and vehicle the ingredient was tested in, and where in the paper the number appears. If we cannot trace a rating to a primary source, we leave the ingredient out.
We did not copy any other website's comedogenic list. Many lists online mix sources, round numbers or carry transcription errors forward; we went back to the papers. The short "why" text for each ingredient is our own summary of what the source reported.
How to read a rating
Grades run from 0 to 5. Following the original study's own interpretation, the checker treats 4–5 as a positive result, 2–3 as borderline (both are "flagged"), and 0–1 as not significant. When sources disagree, the checker shows the range and uses the higher grade. Ingredients we have no published test for are listed as "no published rating", which is not the same as safe. The comedogenic scale page explains the test itself and its limits in detail.
How the checker reads your list
- It splits the list on commas, semicolons, new lines and bullets, but keeps commas inside brackets together, as in
Iron Oxides (CI 77491, CI 77492). - It removes "Ingredients:" headings, percentages, asterisks and trailing full stops, and ignores case, accents and hyphens.
- It treats each alternative name as a possible match:
Water/Aqua/Eau,Paraffinum Liquidum (Mineral Oil), Colour Index numbers. - Anything after "may contain" or "+/-" is shown as a possible colorant with no position, because those are not present in every batch.
- Small misspellings of longer names are corrected and labeled "read as …". It never corrects across numbers, so Laureth-4 can't be mistaken for Laureth-23.
- All of this runs in your browser. The list is never uploaded; see the privacy policy.
Ingredient pages
Most ingredients appear only in the checker and the ratings table. An ingredient gets its own page only when there is enough specific, sourced material to say something useful about it: what exactly was tested and found, where the evidence disagrees, what concentrations and products it turns up in, and what to look for instead. Before a page is published, a separate reviewer checks it against that standard and drops it if the content could be swapped onto another ingredient's page. 19 ingredients currently have a page.
Articles
Articles are researched from published studies and professional guidance, and drafted with the help of AI writing tools. Each factual claim links to its source, and we check those links before publishing. Articles carry a published date and, when changed, an updated date.
What we are not
Skinredients is not written by a dermatologist and is not medical advice. We do not test products ourselves. We are not paid by any brand. See the disclaimer and disclosure.
Corrections
If you find a rating that doesn't match its source, a study we have missed, or a label name the checker does not recognize, email us. Corrections change the data version shown at the top of this page.