Learn

Evidence-based skincare

Plain-language explainers, each grounded in the study behind the claim. We cite our sources and stick to what the research actually measured.

Browse the dictionary

Red marks and brown marks fade differently — which actives work on which, and why sunscreen decides whether anything works.

Dark-spot routine templates Azelaic acid Tranexamic acid Alpha arbutin

Skin concerns
PIE vs PIH: why the color of your acne marks decides the treatment
Red marks and brown marks are different conditions with different fixes — and most 'fade your dark spots' advice only applies to one of them.
June 22, 20263 min readUpdated Jul 2026
Actives
Vitamin C: the antioxidant claim, and the trial behind it
L-ascorbic acid is the most-hyped antioxidant in skincare. A six-month placebo-controlled study is where the smoothing claims come from.
June 12, 20262 min readUpdated Jun 2026
Evidence & myths
Sunscreen myths, checked against the evidence
Every two hours, everywhere, forever? PA ratings? Tinted formulas? What the reapplication rules and the ratings actually mean, and which habits earn their effort.
June 19, 20263 min readUpdated Jul 2026