Reading a makeup ingredient list is not straightforward. INCI names — the international standard used on cosmetic packaging — are designed for consistency, not readability. Cyclopentasiloxane, polytetrafluoroethylene, imidazolidinyl urea — these are the real names of ingredients that appear in everyday makeup, and they tell you very little unless you already know what to look for.
This glossary covers the ingredients we flag at Mrs Makeup — the ones with documented health or environmental concerns that appear most commonly in mainstream products, including many marketed as clean, natural, or non-toxic. For each one: what it is, why it is flagged, where it appears, and what to look for on the label.
Every ingredient listed here is screened for in our product database before a recommendation is made. Products containing any hard-flag ingredient below are not added and will not be recommended.
Hard-Flag Ingredients — Automatic Disqualification
A single confirmed hard-flag ingredient means a product does not enter our database. No exceptions for popular brands, premium prices, or strong reviews.
Parabens
What to look for on the label:
methylparaben · ethylparaben · propylparaben · butylparaben · isobutylparaben · [any ingredient ending in -paraben]
Parabens are preservatives used across foundations, concealers, mascaras, and lip products to prevent bacterial and mould growth. They are effective and inexpensive, which is why they remain widely used despite growing regulatory concern.
The concern is endocrine disruption. Parabens mimic oestrogen in the body — they have been detected in human breast tissue and urine, and studies have linked them to hormonal interference at low concentrations. The EU has banned propylparaben and butylparaben in leave-on products for children under three and restricted concentrations across product types. Methylparaben and ethylparaben remain in widespread use.
Our standard excludes all parabens regardless of type or concentration. Daily makeup exposure represents cumulative contact over months and years — a level of caution the regulatory limits do not fully reflect.
PFAS — Per- and Polyfluoroalkyl Substances
What to look for on the label:
PTFE · polytetrafluoroethylene · perfluorooctyl triethoxysilane · any ingredient beginning with “perfluoro” or “polyfluoro”
PFAS are a class of thousands of synthetic chemicals used in waterproof and long-wear cosmetics for their ability to repel water and oil. They are found in waterproof mascaras, long-wear foundations, and some setting products. PTFE — better known as Teflon — is the most commonly found PFAS compound in makeup.
PFAS are known as "forever chemicals" because they do not break down in the body or the environment. They accumulate in fatty tissue over time and have been linked to immune dysfunction, thyroid disruption, reproductive effects, and increased cancer risk. They enter the water supply when products are washed off and are increasingly detected in human blood, breast milk, and organs.
EU regulation is tightening on PFAS but has not yet imposed a broad cosmetics ban. Products containing any identifiable PFAS compound are excluded from our database entirely.
Cyclotetrasiloxane (D4)
What to look for on the label:
cyclotetrasiloxane · D4 · octamethylcyclotetrasiloxane
D4 is a cyclic silicone — a silicone-based compound used in foundations, primers, and concealers to give them their smooth, silky slip and blurring finish. It is one of the most widely used texture agents in premium cosmetic formulas.
D4 is classified as a Substance of Very High Concern under EU REACH regulation and is banned in wash-off cosmetics and restricted in leave-on products above 0.1% concentration. It is persistent in aquatic environments, bioaccumulative, and has documented endocrine disruption potential — the combination that places it in the most serious regulatory category.
D4 is a hard flag in our standard. Any confirmed D4 presence means a product is excluded from our database. D5 and D6 — related cyclic silicones — are assessed separately as soft flags. See below.
Carbon Black
What to look for on the label:
CI 77266 · Carbon Black · Lamp Black · D&C Black No. 2
Carbon black is a petroleum-derived black pigment produced by the incomplete combustion of heavy oil products. It delivers the intense, rich black colour found in most conventional mascaras and eyeliners. It is one of the most effective black pigments available to cosmetic formulators — and one of the most concerning.
The International Agency for Research on Cancer (IARC) classifies carbon black as a Group 2B possible human carcinogen. It appears in a large proportion of mascaras across all price points — including many marketed as natural or organic. EU regulation restricts its concentration in cosmetics but does not ban it outright.
The alternative is iron oxide pigments (CI 77499), which produce a slightly less intense black but carry none of the safety concerns. Several of the best-performing mascaras in our database use iron oxides exclusively. If your mascara does not list CI 77266, that is a good sign — if the brand does not publish its ingredient list at all, that is a significant red flag.
Microplastics
What to look for on the label:
polyethylene · nylon-12 · nylon-6 · polymethyl methacrylate (PMMA) · polypropylene · polyurethane · acrylates copolymer
Microplastics in cosmetics are intentionally added solid plastic particles — used as exfoliants, texturisers, film formers, and bulking agents. They enter waterways when products are rinsed off, are not removed by standard water treatment, and accumulate in marine environments, food chains, and increasingly in human blood and tissue.
The EU introduced a restriction on intentionally added microplastics in cosmetics in 2023, with phased implementation running to 2035 depending on product type. Many products currently on Irish shelves still contain them, and the transition is incomplete across the industry.
Our standard excludes microplastics entirely, ahead of the regulatory timeline. Identifying them on a label requires knowing the polymer names above — they are not labelled as "microplastics" in any INCI list.
Formaldehyde Releasers
What to look for on the label:
DMDM hydantoin · imidazolidinyl urea · diazolidinyl urea · quaternium-15 · bronopol · sodium hydroxymethylglycinate
Formaldehyde releasers are a class of preservatives that work by slowly releasing small amounts of formaldehyde into the product over time. They prevent bacterial and fungal growth effectively — at the cost of releasing a known human carcinogen as a byproduct of their function.
Formaldehyde is classified as a Group 1 known human carcinogen by IARC, associated with nasopharyngeal cancer and leukaemia at occupational exposure levels. It is also a common skin sensitiser and allergen. The EU restricts formaldehyde content in cosmetics and requires labelling above certain thresholds, but formaldehyde releasers themselves remain permitted at concentrations where the released formaldehyde stays below those limits.
Our standard excludes all formaldehyde releasers regardless of the calculated release rate. The presence of the releasing compound in a daily-use product is sufficient for disqualification.
Phthalates
What to look for on the label:
dibutyl phthalate (DBP) · diethyl phthalate (DEP) · dimethyl phthalate (DMP) · fragrance / parfum [may conceal phthalates]
Phthalates are plasticisers used in nail polish, hairspray, and some fragrances to increase flexibility and longevity. Several are also used as fragrance fixatives and solvents. The EU has banned the most concerning phthalates (DBP, DEHP, BBP) in cosmetics, but DEP remains widely permitted and in use.
Phthalates are endocrine disruptors with documented effects on reproductive hormones, particularly in relation to testosterone. They are frequently hidden within "fragrance" or "parfum" INCI declarations, where individual fragrance components do not need to be listed. This makes them one of the harder ingredient categories to identify from a label alone.
Our standard flags all declared phthalates. Where fragrance appears in a formula from a brand with a history of phthalate use, we treat that as a soft flag requiring further investigation before a product can be accepted.
Oxybenzone
What to look for on the label:
benzophenone-3 · oxybenzone · 2-hydroxy-4-methoxybenzophenone
Oxybenzone is a UV filter used in BB creams, tinted moisturisers, and foundations that include SPF. It is highly effective at absorbing UVA and UVB radiation — but it is also absorbed through the skin at measurable levels and has documented endocrine disruption characteristics.
Studies have detected oxybenzone in blood, urine, and breast milk after topical application. It has shown oestrogenic and anti-androgenic activity in research. The EU permits it at up to 6% in leave-on products; several other countries and regions have tightened restrictions significantly. It is also damaging to coral reef ecosystems, which has led to bans in reef-sensitive coastal areas.
Mineral UV filters — zinc oxide and titanium dioxide — are the clean alternative. They sit on the skin rather than penetrating it, are well tolerated by sensitive skin, and have no documented systemic concerns. Several BB creams and tinted moisturisers in our database use mineral filters exclusively.
Hydroquinone
What to look for on the label:
hydroquinone · 1,4-benzenediol · p-dihydroxybenzene
Hydroquinone is a skin-lightening agent used in concealers, colour-correcting products, and some tinted moisturisers. It works by inhibiting melanin production and is effective at reducing hyperpigmentation — but it is also associated with a condition called ochronosis, a paradoxical darkening of the skin with prolonged use, as well as potential carcinogenic risk at higher concentrations.
Hydroquinone is banned in cosmetics across the EU at concentrations above 0.3% (except in nail hardeners). Despite this, products containing it — particularly those imported from outside the EU — occasionally appear on the Irish market. It remains in widespread use in markets with less restrictive regulation.
Our standard excludes hydroquinone entirely. Safer alternatives for hyperpigmentation include niacinamide, azelaic acid, and alpha-arbutin, all of which have better safety profiles and appear in several products in our database.
Soft-Flag Ingredients — Reviewed in Context
Soft flags do not automatically disqualify a product. They are ingredients that warrant attention and are reviewed in context — considering the product type, likely concentration, and who is most likely to be affected.
Cyclopentasiloxane & Cyclohexasiloxane (D5, D6)
What to look for on the label:
cyclopentasiloxane · D5 · decamethylcyclopentasiloxane · cyclohexasiloxane · D6 · dodecamethylcyclohexasiloxane
D5 and D6 are cyclic silicones closely related to D4 and used for the same purpose — giving makeup its smooth, blurring, skin-like finish. They are among the most common texture ingredients in foundations, primers, and concealers across all price points.
The concern with D5 and D6 is primarily environmental rather than a direct consumer health risk. Both are persistent in aquatic ecosystems and accumulate in sediment and marine organisms. The EU restricts D5 to below 0.1% in wash-off cosmetics and has proposed extending restrictions to leave-on products, with full implementation expected by 2027. The science on direct human toxicity at cosmetic use levels is less conclusive than for D4.
Our standard treats D5 and D6 as soft flags rather than automatic disqualifiers. Products containing them are noted and reviewed in context — they will not appear in recommendations for sensitive skin, but they are not excluded from the database entirely. This reflects the distinction between their environmental concern and the less settled evidence on direct human health risk in leave-on use. D4 remains a hard flag with no exceptions.
Fragrance / Parfum
What to look for on the label:
fragrance · parfum · aroma
Fragrance is the leading cause of cosmetic contact dermatitis. A single "fragrance" or "parfum" declaration on an INCI list can represent a mixture of hundreds of individual chemicals — none of which need to be disclosed individually under EU labelling rules (with limited exceptions for known allergens above threshold concentrations).
Fragrance is a soft flag rather than a hard flag because its impact depends heavily on context. A fragrance in an eyeshadow at a low position in the formula is a different level of concern to fragrance near the top of a daily-wear liquid foundation. Products with fragrance are reviewed individually — but for sensitive skin, fragrance-free is always the safer choice.
Alcohol Denat
What to look for on the label:
alcohol denat · denatured alcohol · SD alcohol · ethanol [at high formula positions]
Alcohol denat is a drying, barrier-disrupting solvent used in setting sprays, primers, and lightweight foundations for its quick-drying and mattifying properties. It is not harmful in the same category as the hard-flag ingredients, but it is a significant concern for dry, sensitive, or compromised skin where barrier function is already reduced.
Formula position matters. Alcohol denat high in the ingredient list — meaning high concentration — in a leave-on product for the face is a meaningful concern. In a nail product or at a low formula position, the concern is reduced. Products are reviewed in context.
Sensitising Essential Oils
What to look for on the label:
lavandula angustifolia (lavender) oil · citrus aurantium · eucalyptus globulus oil · mentha piperita (peppermint) oil · melaleuca alternifolia (tea tree) oil
Essential oils appear frequently in products marketed as natural alternatives to synthetic fragrance. Many are phototoxic, sensitising, or irritating — particularly to reactive or compromised skin. Lavender, citrus, eucalyptus, peppermint, and tea tree are the most common sensitisers we encounter in "natural" formulas.
Essential oils are not a hard flag because many people tolerate them well and some have genuine skin benefits in appropriate concentrations. They are flagged as soft flags and are noted in product reviews, with particular attention given to products recommended for sensitive skin.
High Comedogenic Ingredients
What to look for on the label:
isopropyl myristate · coconut oil (cocos nucifera) · wheat germ oil · lanolin · algae extract [at lead formula positions]
Comedogenic ingredients are those with a documented tendency to clog pores. Not all skin types are equally susceptible — what triggers congestion in acne-prone skin may be entirely tolerated by dry or normal skin. The concern is most relevant in foundations, primers, and concealers worn over large areas of the face daily.
These are soft flagged at significant formula positions — meaning they appear early in the ingredient list, suggesting a meaningful concentration. At low positions they are generally not a concern. Products flagged for comedogenicity are noted in recommendations for acne-prone or congestion-sensitive skin types.
Use the Finder to Check Specific Products
If you have spotted a product in a shop or seen it recommended online and want to know whether it contains any of the ingredients above, ask the Mrs Makeup finder. It searches our vetted database and can tell you whether a specific product has been reviewed, what ingredients it contains that match our flag list, and what clean alternatives are available in the same category.
Every product in our database has been checked against this full ingredient standard before being added — not a selective "free from" list, but a comprehensive review covering all hard flags and relevant soft flags for the product type. You do not need to cross-reference every INCI name yourself.
Not sure which products to trust?
Our Beauty Assistant checks ingredients, flags problem formulas, and finds clean alternatives — just ask.
Frequently Asked Questions
No — and this is precisely the problem. EU cosmetics regulation bans or restricts over 1,300 substances, which is stricter than most markets globally. However, several of the ingredients we hard-flag — including carbon black, certain cyclosiloxanes in leave-on products, and many PFAS compounds — remain legally permitted in Ireland and across the EU. Regulation lags behind the science in several areas. Our standard does not wait for the regulation to catch up.
INCI lists are ordered by concentration — the ingredient listed first is present in the highest amount, the last is present in the smallest. Ingredients above 1% concentration must appear in descending order; below 1% they can appear in any order. This means an ingredient appearing near the top of the list is present in a meaningful amount. The technical Latin and chemical names can be cross-referenced against this glossary to identify the common names of concern.
Yes. The Mrs Makeup beauty assistant can explain why any of these ingredients is flagged, what the alternatives are, and which products in our database avoid them. Ask it by ingredient name — common or INCI — and it will tell you where it appears in our standard and what we recommend instead.
No. This covers the ingredients of greatest documented concern that appear most commonly in mainstream makeup. The science on cosmetic ingredients is continually developing. Our standard is reviewed as new evidence emerges. This glossary reflects our current vetting criteria — it is a starting point for understanding what to look for, not an exhaustive toxicology reference.
