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Skincare ingredient conflict checker
Select the actives in your routine and see which pairs need to be separated, which need care, which are fine — and which famous conflicts are actually myths.
CostFree
TimeUnder 1 min
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DataKept on device
Select the actives in your routine
Pick at least two actives to check how they combine.
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The science
Why some actives clash — and why some "conflicts" are myths
01
Real conflicts come in three kinds. Chemical: one ingredient destabilizes another, like benzoyl peroxide oxidizing retinol or copper peptides. Environmental: two ingredients want different pH conditions to work. Tolerance: each is fine alone, but stacked they overwhelm the skin barrier — the classic case being multiple exfoliants plus a retinoid.
02
The most repeated rule online — never mix niacinamide and vitamin C — is a myth. It comes from 1960s research on unstable raw ingredients at high heat, conditions no modern formula experiences. Contemporary products combine them routinely.
03
The practical rule this checker encodes: most conflicts are solved by time, not abstinence. Vitamin C in the morning, retinoid at night; exfoliating acids on alternate evenings. You rarely need to give an ingredient up — you need to schedule it.
The conflicts that are real, and the famous ones that are not
Genuinely worth separating: retinoids with strong AHA/BHA in one routine (stacked irritation, the top routine-killer), benzoyl peroxide with tretinoin applied simultaneously (oxidation — though modern formulations and morning/night splits solve it), and multiple exfoliating acids layered as if they were serums. Largely myth: niacinamide-plus-vitamin-C (the incompatibility came from 1960s unstabilized formulas at high heat; modern versions coexist fine), "retinol and vitamin C cancel out" (different mechanisms, different times of day by convention not chemistry), and peptides-with-acids panic (relevant to a narrow copper-peptide case, generalized into nonsense). The checker flags by evidence tier so you can tell the categories apart.
FAQ
Common questions
What should you never mix with retinol?+
Same-routine benzoyl peroxide (it oxidizes most retinoids — adapalene is the exception) and stacked exfoliating acids (AHA/BHA), which multiply irritation. Both pairs work fine split between morning and night or alternate evenings.
Can I use niacinamide with vitamin C?+
Yes. The supposed conflict is based on 1960s studies of unstable ingredient forms under heat. Modern formulations combine them deliberately. If the pair tingles on your skin, separate them for comfort — but it is not a chemical rule.
Can I use AHA and BHA together?+
Some products combine them and some skin tolerates it, but it is two exfoliation mechanisms at once. If you also use a retinoid, this is usually the combination that tips skin into irritation. Alternating nights is the safer pattern.
What can I NOT mix with retinol?+
Same-night strong exfoliating acids while building tolerance, and benzoyl peroxide in the same application (fine at opposite ends of the day). Everything else on the internet’s scare lists — niacinamide, hyaluronic acid, peptides — pairs fine.
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