Every error,
kept on the record.

Verdict on hydrolysed collagen split into two endpoints (elasticity vs wrinkle depth). Original blanket grade was too generous on wrinkle data.

WHYReader letter (M. Adetola, Lagos) flagged the conflated endpoints. We re-read the meta-analysis.

Hydroquinone 4% maximum US OTC concentration corrected from 'banned' to 'restricted' (Rx-only since FDA 2020 ruling).

WHYOriginal phrasing was sloppy. The substance isn't banned, it requires a prescription.

Added a routing question to distinguish PIH (post-acne) from melasma. Both routed to the Melasma guide previously.

WHYReader letter (R. Vargas, Mexico City). Genuinely useful catch.

PA grade typo: 'PA+++' corrected to 'PA++++' in the at-a-glance card.

WHYSpotted internally during routine audit.

Oral dosing range corrected from '500–1500mg' to '500–1000mg'. The upper figure was extrapolated from a single off-label study.

WHYCaught during the supplement page build, where we re-checked the original Suzuki et al. 2007 paper.

Argireline (acetyl hexapeptide-8) verdict revised from 'Holds up' to 'Misleading'. Original ruling weighted industry-funded studies too heavily.

WHYInternal re-grade after the Issue 11 bakuchiol piece prompted a sweep of 2022 verdicts.

Step 03 (niacinamide) note added: 'Skip if vitamin C causes flushing — they don't antagonise but the cumulative tingle does.'

WHYThree reader letters in two weeks asking the same question.

Half-life of active fragments corrected from '~3 hrs' to '~6 hrs'. Original figure was for the parent compound, not the active metabolites.

WHYSpotted during the dosing question reply (J. Sørensen letter).

Paragraph claiming 'no industry funding has ever been offered to us' retracted. We did receive — and decline — two offers in Q3 2025.

WHYPhrasing was technically incorrect even though the policy outcome is the same. Letter retracted, full account published in Issue 09.