4COMPLEXION's Substack

Why I didn't want to write about DNA repair enzymes

A biochemist's honest take on DNA repair enzymes, skincare products, and whether or not they are worth adding to your routine.

Oct 8 • Marina | 4COMPLEXION

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September 2026

Byoma Longevit-8: a £22 longevity GHK-Cu serum that isn't blue, and a study nobody can read yet

A cosmetic chemist about what's in the bottle, what a proprietary blend actually hides, what a commissioned study can and can't tell us, and whether…

Sep 20 • Marina | 4COMPLEXION

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Shapewear for Your Under-Eye: The Ordinary's Lacto-PDRN Eye Cream, Decoded

What is Lacto-PDRN, how does it work, and is this formula worth trying? A thorough analysis of The Ordinary's newest launch by a cosmetic…

Sep 10 • Marina | 4COMPLEXION

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July 2026

What I am writing when I get back

Annual leave until September. When I'm back: DNA repair enzymes, haircare through perimenopause and menopause and Mothered Silk protein serum.

Jul 23 • Marina | 4COMPLEXION

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Epii HPT6: Sorry, It Won't Rebuild Your Skin

Can Epii's HPT6 Drop and Cream really firm skin in the "deeper layer," as the box says? A cosmetic chemist's formula analysis and what the evidence…

Jul 19 • Marina | 4COMPLEXION

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Shiny, not dewy: how to keep oily skin calm in a heatwave

A cosmetic chemist on why heat makes oily skin worse, the science-backed routine that calms it, the summer breakouts that aren't even acne and why…

Jul 11 • Marina | 4COMPLEXION

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No, ANUA Azelaic acid serum isn't a scam

A cosmetic chemist on neutralised azelaic acid: why it's not a scam, and what it can't do.

Jul 8 • Marina | 4COMPLEXION

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Pregnancy Skincare: The "Avoid" List Is Way Shorter Than You Think

By a cosmetic chemist and biochemist: what to change, what to keep, and why the advice never lines up

Jul 5 • Marina | 4COMPLEXION

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Medik8's Exo-PDRN Prismatic+: What's Real, What's Marketing, And Whether You Need It

A chemist's full INCI breakdown of the most-asked-about serum of the year. I bought it with my own money. No brand contact, no PR sample, no affiliate…

Jul 1 • Marina | 4COMPLEXION

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June 2026

Your 30s are not the decline they're selling you.

A cosmetic chemist on the skincare routine that matches the biology, not the algorithm. Protocol first, then the science, with every claim linked so you…

Jun 27 • Marina | 4COMPLEXION

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Can sunscreen reverse sun damage on its own?

A biochemist on how sunscreen lets your own biology repair sun damage, what the evidence supports. Plus whether you actually need it indoors, by your…

Jun 13 • Marina | 4COMPLEXION

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Does Your Skin Really "Absorb Everything"?

A cosmetic chemist on how little your skincare actually gets past the surface. Clean beauty, wellness, and whether a sunscreen causes cancer.

Jun 6 • Marina | 4COMPLEXION

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