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Two that do the same job. Which is yours?

When two ingredients chase the same goal, the label rarely tells you which to pick. Each page below puts a pair side by side, honestly, helps you choose by your skin, and answers whether you can use the two together. Two that do different jobs?See if they mix. Comparing whole products?Use the product comparison tool.

Written by Maya Faour, founder and sole writer; not a dermatologistHow we work →

The clash map

Tap an ingredient: what it clashes with lights red, what wants care amber, what it is fine with green. Tap a second for the verdict and the order; a third for your shelf on the map.

AdapaleneAmmonium lactateAscorbyl GlucosideAscorbyl PalmitateBenzoyl PeroxideBetaine SalicylateBromelainCapryloyl Salicylic AcidCitric AcidEthyl Ascorbic AcidGHK-CuGluconolactoneGlycolic acidHydroxypinacolone RetinoateLactic acidLactobionic AcidMagnesium Ascorbyl PhosphateMalic AcidMandelic AcidPapainPhytic AcidRetinalRetinolRetinyl AcetateRetinyl PalmitateRetinyl PropionateRetinyl RetinoateSalicylic acid (BHA)Sodium Ascorbyl PhosphateSponge spiculesTartaric AcidTazaroteneTHD AscorbateTretinoinNiacinamideVitamin C (LAA)Willow Bark Extract
  • clash: 1 pairs
  • careful: 393
  • fine: 26
  • at rest, nothing is lit: tap an ingredient
The rules are lib/conflicts.ts: 420 pairs among 37 ingredients, drawn from the base, the same engine behind every pair page and the checker. A line is a rule that fired, nothing more; the words a tap shows are the page's own, and there is no score.

The pH each one needs, on one line

Only what a study measured: the window where it worked, and where it broke down. The preservatives and thickeners are left off; their pH is the formula's, not your skin's.

your skinVitamin CRetinolSalicylic acidLactic acidGlycolic acidMandelic AcidAzelaic AcidGHK-CuHydroquinoneHypochlorous Acid23456789pH

At pH 5.0: inside the measured window for Azelaic Acid and Hypochlorous Acid.

Niacinamide: no window to draw. One study (Sjoberg 2026) compared two products and nothing else. Not its own ionisation: pH 7.4 loosened stratum corneum lipids and about doubled permeation vs pH 5.0; acid hydrolysis not measured here.

Drag the handle along the line. Only what was measured is drawn; between the marks nothing was. Your skin's surface: about 4.7 at rest, 5.1 on a normal day.PMID 18489300PMID 11207686PMID 12296993PMID 14706244PMID 14528393PMID 8634803PMID 38881052PMID 22111946PMID 6291585PMID 1934147PMID 14967556PMID 40021972

Compare →

Actives 61

Retinoids, vitamin C forms and the other workhorses. Same job, different trade-offs.

Exfoliants 12

AHAs, BHAs and enzymes. Which acid suits which skin.

Antioxidants 8

The protectors. What each one is actually best at.

Hydrators 26

Humectants that pull water into the skin. Closer than the marketing suggests.

UV filters 3

The filters inside a sunscreen, compared honestly.

Why the order

On freshly cleansed skin, thinner and lower-pH goes on first and richer goes on last: exfoliating acids and pure vitamin C on bare skin, then watery serums and humectants on damp skin, then creams, oils and balms over them, and sunscreen last of all in the morning. Two ingredients at the same step can go in either order; apply the thinner one first. A pair that should not share a routine says so on its own page, with the split.

How we score every ingredient →