The Sensitive Skin Label Literacy Guide (UK)

The definitive plain-English UK guide to reading skincare, cosmetic and household labels when your skin is reactive. What matters, what does not, and the 60-second routine that catches the vast majority of triggers.

Short answer. In the UK, the front of a skincare pack is marketing; the back is law. Turn every product over and read the ingredients list (INCI format) with three shortlists in mind: fragrance names, preservative names, and specific known triggers. A 60-second routine catches the vast majority of what causes reactive skin to flare. This guide is the anchor - everything on the site links back here for the mechanics of reading a label.

Why the front of the pack cannot be trusted

None of the words on the front of a UK cosmetic pack are legally defined. “Fragrance-free” is not regulated. “Unscented” is not regulated. “Hypoallergenic” is not regulated. “Dermatologically tested” means a dermatologist was somehow involved in the testing process; it does not tell you what was tested, on whom, or what the result was. “Suitable for sensitive skin” is a brand assertion, not a certification.

This is not a conspiracy. It is how UK cosmetic law is structured. The parts of the label that carry legal weight are:

• The INCI ingredients list on the back of the pack.
• The Responsible Person’s name and address (usually in small print).
• The batch code and best-before / period-after-opening symbol.
• The 26 named fragrance allergens (soon to be expanded), which must be individually declared in the INCI when present above a low threshold.

Everything else is marketing. Which means for someone with reactive skin, learning to read the INCI is the single most useful skill in skincare.

For more on this specifically: fragrance-free is not a regulated term.

What INCI is (in one paragraph)

INCI stands for International Nomenclature of Cosmetic Ingredients. It is a global naming standard so that the same ingredient is called the same thing on every cosmetic label in the world. Water becomes Aqua. Vitamin E becomes Tocopherol. Lavender oil becomes Lavandula Angustifolia Oil. This is why cosmetic ingredient lists look full of Latin - the Latin is the global name for a plant or a chemical, applied consistently. Once you know the INCI names, you can read a UK cream, a French sunscreen, and a Japanese cleanser with equal confidence.

The order matters

Ingredients on a UK cosmetic label appear in descending order of concentration down to 1%, after which the remaining ingredients can appear in any order. This means:

• The top 5 to 10 ingredients make up most of the product. These are the actives, the base emulsifier, and the main texture-forming ingredients. If your skin reacts to a specific texture (heavy occlusive vs light gel), the answer is usually in the top of the list.
• The middle contains functional ingredients at 1 to 5% concentration - actives, humectants, secondary emollients.
• The bottom third contains preservatives, fragrance ingredients, individual fragrance allergens, and colourants. This is where reactive skin trouble almost always sits.

For sensitive skin, the bottom third is what you read first.

The three shortlists

Three categories cover most reactive-skin flares. Learning to spot the names in each turns the INCI list into a fast decision.

Shortlist 1 - fragrance

Fragrance is the single most common cause of cosmetic allergy in the UK. Any of the following in the INCI means fragrance is present:

• Parfum / Fragrance / Aroma - the umbrella terms. Aroma is used in oral and lip products, but the same category.
• Any of the 26 named fragrance allergens. The most common ones you will see: Limonene, Linalool, Citronellol, Geraniol, Citral, Coumarin, Eugenol, Cinnamal, Benzyl Alcohol, Farnesol. The full 26 (and the expanded list now rolling out) is in the 26 named fragrance allergens hub.
• Any essential oil. These follow the pattern [Botanical Latin name] Oil or Extract - Lavandula Angustifolia Oil (lavender), Melaleuca Alternifolia Oil (tea tree), Citrus Aurantium Dulcis Oil (sweet orange), Mentha Piperita Oil (peppermint), Rosa Damascena Oil (rose). Essential oils are natural, they are also fragrance, and they contain the same named allergens as synthetic fragrance. See natural doesn’t mean safe: essential oils.

Read the last third of the INCI list. If any of the above appears, fragrance is present - regardless of what the front of the pack says.

Shortlist 2 - preservatives

Preservatives keep water-based skincare from growing bacteria and mould. They are necessary. But some sensitise a real proportion of the population.

• Isothiazolinones - the biggest single category of preservative allergy in UK dermatology. Names to know: Methylisothiazolinone (MI), Methylchloroisothiazolinone (MCI), Benzisothiazolinone. Banned in leave-on cosmetics since 2015; still legal in rinse-off up to 15 ppm, and still causes the majority of preservative reactions.
• Formaldehyde-releasers - slowly release trace formaldehyde over shelf life. Names to know: Quaternium-15, DMDM Hydantoin, Imidazolidinyl Urea, Diazolidinyl Urea, Bronopol, Sodium Hydroxymethylglycinate.
• Iodopropynyl Butylcarbamate (IPBC) - a rising cause of contact dermatitis, especially in baby wipes.

The lower-risk preservatives (Phenoxyethanol, Ethylhexylglycerin, Sodium Benzoate + Potassium Sorbate, Sodium Levulinate, Caprylyl Glycol) are what dermatology-focused UK brands tend to use. See the preservatives hub for the full picture.

Shortlist 3 - specific known triggers

A handful of ingredients cause a disproportionate share of reactive-skin problems.

• Lanolin (also Lanolin Alcohol, Wool Alcohols) - a common cause of eyelid and lip dermatitis.
• Sodium Lauryl Sulfate (SLS) - a strong surfactant, mostly irritant rather than allergic, but rough on already-reactive skin.
• Cocamidopropyl Betaine - a “mild” surfactant that is actually one of the more common allergens in shampoos.
• Propylene Glycol - a solvent that can be both irritant and allergic.
• Colophonium / Colophony (pine rosin) - hidden in some balms and cosmetics; a common patch-test allergen.
• Nickel-adjacent - Nickel Sulfate almost never in cosmetics (it is a jewellery and metal issue), but nickel-allergic patients sometimes react to certain pigments.

For each named allergen the site has an ingredient page - see the ingredients index.

The 60-second label-reading routine

Once the three shortlists are familiar, the routine is fast:

1. Turn the product over.
2. Read the last third of the INCI list first. Fragrance ingredients and named allergens live here. If any of the fragrance shortlist appears, fragrance is present.
3. Scan the whole list for essential oils. Look for [Botanical Latin name] Oil or Extract. Essential oils are also fragrance.
4. Scan for preservatives. Look for names ending -isothiazolinone, -hydantoin, -urea, or the letters IPBC.
5. Scan for the specific known triggers. Lanolin, SLS, cocamidopropyl betaine, propylene glycol, colophonium.
6. Decide. If any of your personal triggers appears, put it back. If none does and the last-third fragrance shortlist is clear, the product is fragrance-free by any working definition, and safer than the front of the pack alone can tell you.

Sixty seconds. Every product. Every time. This is the habit.

What matters less than most people think

• Order past position 20 or 30. The concentration is too low to matter for most purposes. Unless a specific allergen you have patch-tested to is in there, ingredients this far down usually do not drive reactions on their own.
• Colour or country of origin of the pack. UK-sold products of any origin must comply with UK cosmetic law and carry a UK-format INCI. A French, German, or Korean brand sold legally in the UK has the same standard.
• Marketing categories (“clean beauty”, “natural”, “vegan”, “cruelty-free”). None of these translate to sensitive-skin safety. Vegan products can be heavily fragranced. Clean beauty can include essential oils that provoke allergic contact dermatitis. Cruelty-free tells you about the testing model, not the finished formula.
• PAO (Period After Opening) symbol. The small tub-with-a-lid icon showing “12M” or “6M” is useful for shelf-life management but does not indicate anything about the ingredients.

The food crossover

If you have already sorted out your skincare and your skin still flares, the next place to look is what you eat. A meaningful fraction of adults with atopic dermatitis and chronic urticaria are food-sensitive - most commonly to the named fragrance chemicals that also appear in food, or to salicylates and histamine, all of which appear on food labels as either specific E-numbers or naturally-occurring chemicals in whole foods.

Two starting points: the food additives and skin hub covers additive triggers with E-number links; the food-driven hives vs a contact rash guide helps distinguish which mechanism you are dealing with.

When to escalate to a professional

• If your skin is not settling despite a clean, short-INCI routine.
• If you suspect a specific allergen and want confirmation - patch testing at a UK dermatology clinic is the answer.
• If your skincare and food are both clean and reactions persist.
• If a child or infant is involved - paediatric dermatology or a specialist paediatric dietitian is the right route.

The GP is the referral gateway. Bring a two-week diary of what you used, what your skin did, and what settled it. That short record often gets to the diagnosis faster than any test.

Where to go next from here

• You want the fragrance detail: 26 named fragrance allergens hub and natural doesn’t mean safe: essential oils.
• You want the preservative detail: preservatives in skincare hub.
• You have just reacted to a new product: I reacted - find the likely culprit.
• You need to know if the reaction is allergic or irritant: allergic vs irritant contact dermatitis.
• You suspect food is involved: food additives and skin hub.
• You want to compare scanner apps: the compare index has honest UK-focused round-ups.

Every page on this site links back here. This is the anchor - the definitive answer to “how do I read a label with reactive skin”. Bookmark it, share it, and use the routine.

Written and reviewed by the Sensitive Skin Lab editorial team.