Sources we use

Our guides answer everyday beauty questions for US readers. We use sources in this order of weight:

1. Regulators and professional guidelines: the US FDA, the American Academy of Dermatology (AAD), the EU Scientific Committee on Consumer Safety (SCCS) and CosIng database, the Cosmetic Ingredient Review (CIR) and Korea's Ministry of Food and Drug Safety (MFDS).
2. Systematic reviews and controlled human trials.
3. Small or open-label human studies.
4. Cell and animal studies.
5. Manufacturer data, attributed to the manufacturer.

We cite studies we have read, at minimum the PubMed abstract, and link the PubMed, PMC or DOI record. Where a study reports them, we give the number of participants, the duration, the concentration tested and the comparator. Every article lists its sources with the date they were checked.

How we grade evidence

Each claim in an evidence table carries one of five grades:

• Strong: multiple controlled human trials or a systematic review.
• Moderate: at least one controlled human trial.
• Limited: small, open-label or vehicle-free human data.
• Lab-only: cell (in vitro) or animal studies.
• Guidance: a recommendation or safety assessment from a regulator or professional body (for example FDA, AAD or the Cosmetic Ingredient Review panel), not a trial result.

Our wording follows the grade. Lab-only findings are described as results "in cell studies"; a single small trial as, for example, "one 8-week study of 30 people"; several controlled trials as "controlled trials suggest". Evidence for an ingredient is kept separate from evidence for a finished product: we state whether a product discloses its concentration and whether the formula itself was tested.

Cosmetic language

Our guides cover cosmetic concerns: how skin, hair and nails look and feel. We describe results in cosmetic terms, such as "improved the appearance of" or "reduced visible redness in the study group". When a skin condition such as acne, eczema, rosacea or melasma is part of the question, we point readers to a board-certified dermatologist. Regulatory status is stated precisely, for example an FDA OTC monograph, an EU SCCS opinion or a Korean MFDS functional cosmetic listing, with the date we checked it.

Product articles

Product articles decode the formula from the full ingredient list, connect the key ingredients to the research above, and attribute a brand's own test results to the brand, with the sample size and year when published. Summaries of Korean user reviews give the number of reviews and their date range. Prices are dated observations; a Korean promotional set and a US listing can differ in size, bonus items or formula, and shopping notes identify known differences.

Affiliations and advertising

The site is supported by advertising (Google AdSense, once approved, with ads clearly separated from articles) and by Amazon affiliate links. Some product articles include Amazon affiliate links. As an Amazon Associate I earn from qualifying purchases, and Amazon affiliate links are disclosed beside the link. Source links are evidence, not endorsements. We do not operate an Olive Young affiliate program.

Fact-checking and images

Each article is checked against its linked sources before publication.

Official product images are credited to their source. Editorial scenes and title cards are labeled "Illustrative image."

Corrections

If a source has changed, a formula has been reformulated or a statement is wrong, please send the article URL and the correction through our contact page. We recheck the source, correct the article and show an updated date on substantive revisions.