The scanner, written out
The ingredient library
What each ingredient actually does, who it suits, and what not to put it next to. The app's product scanner runs this thinking live against your skin profile when you scan a barcode — this is the reference edition.
Most skincare problems are not caused by missing a hero ingredient. They come from too many actives at once, layers that fight each other, or one quiet irritant left in the routine for months. Removing the wrong ingredient usually beats adding a right one.
- Generally safe 16
- Use with care 10
- Usually skip 4
Browse by category
Eleven hubs from the same category tags on each ingredient page — not a generated category-by-skin grid.
Active
Skincare actives
Targeted leave-ons that change how skin behaves over weeks — retinoids, niacinamide, acne actives, and similar workhorses — not moisturisers in disguise.
Exfoliant
Chemical exfoliants
AHAs and BHA that loosen dead cells and clear congestion — useful when you want texture change, risky when you stack them with other turnover actives.
Hydrator
Hydrators
Humectants that pull and hold water in the outer skin — the quiet step oily and dry skin both skip for the wrong reasons.
Barrier
Barrier-support ingredients
Ceramides, panthenol, centella and similar — the repair bench when actives have pushed skin past comfortable.
Antioxidant
Antioxidant ingredients
Daytime support players such as vitamin C and green tea extract — useful beside sunscreen, not a substitute for it.
Brightening
Brightening ingredients
Tone-focused ingredients such as kojic acid and tranexamic acid — slow, cumulative, and easy to over-promise in marketing.
Sunscreen filter
Sunscreen filters
The UV-blocking ingredients that make a sunscreen work — starting with mineral zinc oxide in this library.
Preservative
Preservatives in skincare
The unglamorous ingredients that keep water-based products from growing microbes — phenoxyethanol is the example documented here.
Surfactant
Surfactants & cleansing agents
Detergents and solvents that remove oil and product — useful in cleansers, harsh when left on or overused.
Emollient
Emollients & occlusives
Oils, silicones, and similar sealers that soften and reduce water loss — helpful for dry skin, congestion risks for others.
Fragrance
Fragrance in skincare
Scent ingredients that make products smell like a lifestyle brand — common trigger for reactive skin, optional for everyone else.
Browse by skin type
Five hubs built from each ingredient's best-for and caution-for lists — the same axes the scanner already uses.
Skin type
Ingredients for normal skin
A flexible baseline: most library ingredients mark normal skin as a fit, so the job is choosing goals — not surviving every bottle.
Skin type
Ingredients for dry skin
Humectants, barrier lipids, and emollients first — strong acids and aggressive surfactants last.
Skin type
Ingredients for oily skin
Oil control without stripping: niacinamide, thoughtful BHA use, and lightweight hydration — not three foaming cleansers.
Skin type
Ingredients for combination skin
Zone-aware routines: treat the oily T-zone and drier cheeks as different jobs, not one average face.
Skin type
Ingredients for sensitive skin
Fewer variables, fragrance skepticism, and barrier-first picks — strong actives only with a slow on-ramp.
Can I mix…?
Hand-picked pairing pages from the same avoid-with and pairs-well edges the scanner uses — not a full ingredient matrix. Each answer is cosmetic layering guidance only.
Do not layer in one step
Can I mix retinol and benzoyl peroxide?
Not in the same application. The combo is irritating and can deactivate some retinoids — alternate nights, or use benzoyl peroxide in the morning and retinol at night.
Do not layer in one step
Can I mix retinol and salicylic acid?
Skip same-night layering. Both increase turnover and dryness — use salicylic acid on non-retinol evenings, or keep BHA to a rinse-off if you need both.
Do not layer in one step
Can I mix retinol and glycolic acid?
Not on the same night. Glycolic acid is the most penetrating common AHA; stacked with retinol it is how barriers get wrecked — alternate evenings and wear sunscreen.
Do not layer in one step
Can I mix vitamin C and benzoyl peroxide?
Avoid layering them in one step. Benzoyl peroxide can oxidise ascorbic acid, and the pair is harsher on skin — use vitamin C in the morning without BPO on top, or separate days.
Do not layer in one step
Can I mix salicylic acid and glycolic acid?
Do not stack leave-on AHA and BHA in one step. Pick the acid that matches the job — salicylic inside pores, glycolic on surface tone — and alternate nights.
Layers well
Can I mix niacinamide and retinol?
Yes. They layer well — niacinamide supports the barrier while retinol does the heavy lifting. Use niacinamide before or after retinol, or pick a formula that already combines them.
Generally safe
Well tolerated by most skin types. These are the ingredients you can usually add without a settling-in period.
Active
Niacinamide
A vitamin B3 derivative that supports the skin barrier, calms redness, and gradually evens tone. One of the few actives almost everyone tolerates.
Active
Bakuchiol
A plant-derived ingredient often marketed as a gentler retinol alternative. Better tolerated, with a much smaller evidence base.
Hydrator
Hyaluronic Acid
A humectant that holds water in the upper layers of skin. Harmless, popular, and frequently used wrong.
Hydrator
Glycerin
The most reliable humectant in skincare, in almost every moisturiser you have ever used, and cheap enough that nobody markets it.
Barrier
Ceramides
Lipids your skin barrier is already made of. The right answer when skin is tight, flaky, stinging, or over-exfoliated.
Exfoliant
Mandelic Acid
The largest common AHA and the gentlest. A good option for sensitive skin and for deeper skin tones prone to post-inflammatory marks.
Active
Azelaic Acid
An unusually versatile active that handles redness, spots and dark marks at once, and is gentle enough for most sensitive skin.
Emollient
Squalane
A lightweight, stable oil that mimics something your skin already produces. Rarely causes breakouts and suits nearly everyone.
Barrier
Panthenol
A soothing humectant that helps calm irritated, over-treated skin. Common in barrier repair creams and after-sun products.
Barrier
Centella Asiatica
The "cica" of Korean skincare. A soothing botanical with reasonable evidence for calming redness and supporting barrier recovery.
Sunscreen filter
Zinc Oxide
A mineral UV filter with genuine broad-spectrum coverage. The default recommendation for sensitive and reactive skin.
Emollient
Dimethicone
A silicone that smooths skin, reduces water loss, and takes far more criticism than the evidence justifies.
Brightening
Tranexamic Acid
A gentle, well-tolerated brightening agent with growing evidence for stubborn pigmentation, including melasma.
Hydrator
Urea
A humectant at low strengths and a keratolytic at high ones. Excellent for genuinely dry, rough or thickened skin.
Active
Peptides
Short chains of amino acids marketed as collagen signals. Well tolerated, plausible mechanism, modest and inconsistent real-world evidence.
Antioxidant
Green Tea Extract
A well-tolerated antioxidant botanical with anti-inflammatory properties. A good supporting ingredient, not a headline one.
Use with care
Effective, but with a real irritation or adjustment cost. Introduce one at a time and give each a few weeks before judging it.
Active
Retinol
The best-evidenced over-the-counter anti-ageing and acne active, and also the one most likely to make your skin worse before it gets better.
Antioxidant
Vitamin C
A morning antioxidant that brightens tone over time and boosts what sunscreen is already doing. Notoriously unstable in its pure form.
Exfoliant
Salicylic Acid
An oil-soluble exfoliant that gets inside pores. The standard choice for blackheads and congestion, and easy to overdo.
Exfoliant
Glycolic Acid
The smallest AHA, so the most penetrating and the most irritating. Strong results on texture and tone if your skin can take it.
Exfoliant
Lactic Acid
A larger, gentler AHA that exfoliates and hydrates at the same time. The sensible first acid for dry or nervous skin.
Active
Benzoyl Peroxide
The most effective over-the-counter acne ingredient, and the one most likely to dry you out and bleach your towels.
Active
Adapalene
A third-generation retinoid available without prescription in many countries. Stronger evidence for acne than retinol, and more stable.
Preservative
Phenoxyethanol
A widely used preservative that keeps products from growing bacteria. Safe at regulated levels, mildly irritating for a small minority.
Active
Tea Tree Oil
A botanical with real antibacterial activity against acne, and real sensitising potential at the strengths people use undiluted.
Brightening
Kojic Acid
A fungal-derived brightening agent that interferes with pigment production. Effective on dark marks, and a known sensitiser for some.
Usually skip
Commonly irritating in leave-on products, or offering nothing your skin needs. The first things to remove when troubleshooting.
Fragrance
Fragrance
The most common cause of cosmetic contact allergy and irritation, and the ingredient that most often turns a "gentle" product into a problem.
Surfactant
Denatured Alcohol
A volatile alcohol used to make products feel light and dry fast. High in the ingredient list, it is a common cause of dryness and irritation.
Surfactant
Sodium Lauryl Sulfate
A strong cleansing agent that foams well and strips well. Fine in a shampoo, a poor choice for a facial cleanser.
Emollient
Coconut Oil
Excellent on the body, a common trigger for facial breakouts. Highly comedogenic for many people despite its natural-beauty reputation.
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