What this guide is for
Pick up almost any shampoo, sunscreen or moisturiser and you will find at least one ingredient that somebody, somewhere, has told you to avoid. Some of those warnings are well founded. Some are exaggerated, outdated, or based on a single laboratory study that has little to do with the amount of the ingredient in a real product. This guide is our attempt to sort one from the other — calmly, ingredient by ingredient.
Below you will find the complete flagged-ingredients list we maintain, a short course in reading labels, and links to our detailed explainer articles. Each explainer covers what the ingredient is, what it does in a product, where you will find it, why people choose to avoid it, what regulators and the research actually say, how to spot it on a label (including its less obvious names), and what alternatives exist. Nothing here is medical advice; it is label literacy.
How an ingredient ends up on this list
An ingredient appears on this list when a significant number of shoppers actively look for products without it — and there is a real, describable reason behind that behaviour. Sometimes the reason is a well-documented problem, such as a preservative that is a common cause of contact allergy. Sometimes it is a precautionary choice, such as avoiding a UV filter that the body absorbs while longer-term research continues. Sometimes it is environmental: an ingredient that washes down the drain and persists in waterways. And sometimes it is simpler than any of that — an ingredient can be perfectly safe and still be wrong for a particular person's hair or skin.
Being on this list does not mean an ingredient is banned, dangerous at cosmetic doses, or something you must avoid. Where regulators have set limits or bans, our explainers say so specifically. Where the science is unsettled, we describe it as unsettled. You will also notice that dose and context run through every article: many of these ingredients are only a concern in particular product types, at particular concentrations, or for particular people — babies, for example, or people with a diagnosed allergy.
How to read an ingredient label like a formulator
Ingredient lists (the INCI list on the back of the pack) follow rules that make them more useful than most people realise. Ingredients are listed in descending order of concentration down to 1%; below 1% they can appear in any order. That means the first five or so ingredients make up the bulk of any product, and an ingredient near the end — however fashionable — is present in a small amount. Fragrance and flavour components are the big exception: they can be grouped under the single word "fragrance" or "parfum", which is why synthetic fragrance gets its own explainer.
Three habits will take you most of the way. First, learn the label names of the few ingredients that matter to you — several go by multiple names, and our explainers list them. Second, treat "free-from" claims as marketing until you have checked the list yourself; "paraben-free" products still contain preservatives, just different ones, and it is worth knowing what parabens were doing there in the first place. Third, remember that natural is not a synonym for safe and synthetic is not a synonym for harmful — the flagged list includes natural substances used at the wrong strength, and the look-for list includes laboratory-made ingredients with excellent safety records.
The personal-care ingredients people ask us about most
Of the dozens of flagged ingredients we track, a core group generates most of the questions. Parabens and phthalates sit at the centre of the long-running endocrine debate. Sulfates are the everyday irritation question in every shampoo aisle. Oxybenzone anchors the sunscreen debate, alongside its chemical-filter cousins. Formaldehyde-releasing preservatives, PFAS, talc, mineral oil, silicones, PEG compounds and triclosan each have their own distinct story — a contamination question, an environmental question, an allergy question — which is exactly why they each get a full explainer rather than a line in a list.
Start with whichever ingredient is already on a product in your bathroom. That is the fastest way to build the habit: one label, one explainer, one informed decision.
How this guide is maintained
Ingredient regulation is a moving target — a filter restricted in one market, a preservative warning threshold lowered in another — so this guide is maintained as a living document rather than a finished one. When a regulator changes position on an ingredient covered here, the explainer is updated and its "last updated" date moves; when a genuinely new concern ingredient emerges in reader questions (as PFAS did), it is researched and added with the same structure as the originals. If you believe an article here misstates a regulation or a study, the corrections route in our editorial policy is the fastest way to get it fixed — flagged-ingredient information is only useful while it is accurate, and accuracy is a maintenance job, not a launch event.
The flagged ingredients list
| Ingredient | In short |
|---|---|
| Parabens | Preservatives flagged for their ability to weakly mimic oestrogen; the most debated preservative family in cosmetics. |
| Sulfates (SLS & SLES) | Strong cleansers that can strip natural oils and irritate scalps and skin. |
| Oxybenzone (Benzophenone-3) | Chemical UV filter flagged for possible hormone effects and coral-reef toxicity. |
| Phthalates | Plasticisers and fragrance carriers flagged for reproductive and developmental concerns. |
| Synthetic Fragrance | Undisclosed blends under the label word 'fragrance'; a leading cause of cosmetic contact allergy. |
| Formaldehyde & Releasers | Preservatives that slowly release formaldehyde, a known sensitiser and carcinogen. |
| PFAS | 'Forever chemicals' used for wear and water resistance; persistent in the environment and body. |
| Talc | Moisture-absorbing mineral that can be contaminated with asbestos where it is mined. |
| Mineral Oil & Petrolatum | Petroleum-derived occlusives some people avoid for skin feel, congestion and environmental reasons. |
| Silicones | Coating agents (e.g. dimethicone) that can build up on hair and persist in waterways. |
| PEG Compounds | Ethoxylated ingredients whose manufacture can leave trace 1,4-dioxane contamination. |
| Triclosan | Antibacterial agent flagged for antibiotic-resistance and thyroid-hormone concerns. |
| Aluminium Compounds | Antiperspirant actives that block sweat ducts; the subject of long-running, unresolved health debates. |
| Alcohol Denat & Drying Alcohols | Fast-drying alcohols that can strip the skin barrier and cause dryness and irritation. |
| Methylisothiazolinone (MI) | Potent preservative recognised as a leading cause of allergic contact dermatitis. |
| Phenoxyethanol | Preservative many baby-product brands exclude over newborn skin-reaction concerns. |
| Octinoxate | UV filter linked in research to endocrine and marine-environment concerns. |
| Homosalate | UV filter that may accumulate in the body; restricted in the EU. |
| Avobenzone | Effective UV filter that can be unstable in sunlight unless stabilised. |
| Coal Tar | Medicated-shampoo ingredient flagged as a potential carcinogen and irritant. |
| Benzalkonium Chloride | Antimicrobial that can be harsh and drying on delicate skin. |
| Propylene Glycol | Penetration enhancer that causes reactions in a minority of users. |
| Added Sugars | Sugars added to foods (glucose syrup, sucrose, dextrose) beyond what occurs naturally. |
| Added Salt | Sodium added during manufacturing, a concern especially in foods for infants and children. |
| High Fructose Corn Syrup | Industrial sweetener associated with rapid blood-sugar spikes. |
| Hydrogenated Fats | Man-made trans fats that raise LDL cholesterol. |
| Artificial Colours | Synthetic dyes with no nutritional value, flagged in children's-food debates. |
| Artificial Flavours | Synthetic flavour compounds that mask the taste of real ingredients. |
| BHA & BHT | Synthetic antioxidant preservatives scrutinised as suspected endocrine disruptors. |
| Carrageenan | Seaweed-derived thickener some research links to intestinal inflammation. |
| Maltodextrin | Highly processed starch filler with a very high glycaemic index. |
| Sodium Benzoate | Preservative that can form trace benzene when combined with certain acids. |
| Palm Oil | Cheap, versatile fat with environmental costs and infant-nutrition debates. |
| High Intensity Sweeteners | Aspartame, sucralose and similar; gut-microbiome effects are an active research area. |
| TBHQ (E319) | Synthetic antioxidant preservative heavily scrutinised for long-term effects. |
Ingredient explainers
Frequently asked questions
Does 'flagged' mean an ingredient is dangerous?
No. Flagged means many shoppers choose to avoid the ingredient and there is a describable reason — which can range from a well-documented allergy risk to a precautionary or environmental preference. Each explainer states what regulators say, including where an ingredient is permitted and at what limits.
Are products without these ingredients always better?
Not automatically. Removing an ingredient means replacing its job — preservation, cleansing, UV protection — with something else, and the replacement has its own profile. A sulfate-free shampoo, for example, is gentler for many people but may clean heavy product build-up less effectively. Our guides compare trade-offs rather than declaring winners.
Why do regulators allow ingredients that appear on lists like this?
Regulators assess safety at the doses used in products, and different agencies weigh the same evidence differently — several ingredients on this list are restricted in the EU but permitted elsewhere, and vice versa. Disagreement between regulators is one reason shoppers do their own reading, and why we report each position rather than picking one.
I have sensitive skin. Where should I start?
The most common cosmetic sensitivities involve fragrance and certain preservatives, so the explainers on synthetic fragrance and formaldehyde-releasing preservatives are a sensible start, along with our guide to moisturisers without fragrance. For diagnosed allergies, your dermatologist's advice overrides anything on this site.
How do I check a product I already own?
Find its INCI ingredient list (printed on the packaging), then search this guide for any names you are unsure about. Each explainer includes the alternative names the ingredient appears under, which is the part most people miss.