Reading a skincare label can feel like decoding a foreign language. Long chemical names, vague marketing terms, and ingredients that sound natural but aren't or sound scary but are perfectly fine. This glossary exists to cut through that confusion.
When my daughter was going through topical steroid withdrawal, I became obsessed with ingredient lists. Not because I enjoyed it, but because I had to. The overwhelming INCI terminology, the vague label claims, and the single word "parfum" concealing an entire cocktail of compounds made it so hard to understand what was good or bad.
When I created Apothecary & Me, I wanted to ensure that every customer could easily see at a quick glance what was inside our products. We list every ingredient by its INCI name and its common name. We name every essential oil individually. Nothing hides. That commitment to simplicity and full transparency isn't a marketing decision; it's the whole point.
Consider this glossary a living reference, written not for dermatologists, but for the person whose skin has been through it, who wants to make better decisions and stop being misled by marketing. It is not exhaustive, and I will keep adding to it as questions come in from our community. If there is a specific ingredient you would like me to cover, leave a comment, and I will add it.
"The most empowering thing you can do for reactive skin is learn to read the label."
How to Read This Glossary
Ingredients are grouped by category. Each entry explains what the ingredient is, what it does in a formula, and whether it's generally considered safe, worth watching, or best avoided for reactive, sensitive, or compromised skin.
I've used three simple labels throughout:
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Safe for most reactive skin - consistently well-tolerated by people with eczema, rosacea, TSW, psoriasis, or sensitive skin
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Use with caution — may be fine for many, but worth patch testing and monitoring
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Best avoided — commonly linked to irritation, sensitisation, or barrier disruption in reactive skin
These aren't absolute rules. Every skin is different. But they reflect what I've learned from years of formulating, researching, and listening to our community.
Fragrance and Scent Ingredients
In my experience, this is the category that causes the most problems for reactive and compromised skin. It's also the one most deliberately obscured by the industry, and that lack of transparency is at the heart of the problem.
Fragrance / Parfum
Best avoided for reactive skin.
"Fragrance" or "parfum" is a single word on an ingredient list that can represent dozens, sometimes hundreds, of individual chemical compounds. Manufacturers are not legally required to disclose what those compounds are. One word. Endless variables.
Fragrance is one of the leading causes of contact dermatitis and skin sensitisation in cosmetics. It appears in products across every category, including ones marketed specifically for sensitive skin. I've seen it in "eczema creams." I've seen it in products sold in pharmacies next to a picture of a baby. If you have reactive skin of any kind, fragrance-free should be non-negotiable. Not a preference. A rule.
Natural Fragrance
Best avoided for reactive skin.
This term is largely unregulated and, in my opinion, largely misleading. "Natural fragrance" refers to aromatic compounds derived from plants, but the skin doesn't care whether an irritant came from a laboratory or a lavender field. It reacts to the compound itself. For reactive skin, natural fragrance carries the same risks as synthetic fragrance, and the "natural" label gives a false sense of safety that I find genuinely frustrating.
Essential Oils
Best avoided for reactive skin.
I realise this may not be what some people want to hear - I say that as someone who has trained in essential oils and has a deep love for them. I understand their appeal completely. They smell beautiful. They feel natural. And when used well, they are genuinely powerful. But they are highly concentrated, biologically active compounds, and that training is precisely why I know how carefully they need to be treated. For already-compromised skin, they are among the most common triggers I've encountered.
Some of the most reactive skin I've ever seen has been aggravated by products marketed as natural and soothing, with essential oils at the heart of the formula. If your skin is sensitive, inflamed, or in an active flare, essential oil-free is just as important as fragrance-free. The two go together.
I'll be transparent here: some of our own products do contain essential oils - our bath oils, body scrub, and Glow Face Scrub. We include them thoughtfully and never hide behind the word "parfum." Every single oil is named individually on the label with its allergen reference, so you know exactly what you're applying. Our ethos for our skincare when you have compromised or reactive skin is to always start with our unscented products first, and once the skin barrier is rebuilt, then progress to our scented range.
Alcohols
Not all alcohols in skincare are the same, and this trips up a lot of people.
Denatured Alcohol (Alcohol Denat.) / Ethanol / SD Alcohol
Best avoided for reactive skin.
These are the alcohols worth avoiding. They evaporate quickly, giving products a lightweight feel, but they also strip the skin's natural lipid barrier. Used regularly, they contribute to chronic dryness, barrier disruption, and increased reactivity over time. They appear frequently in toners, serums, and gel textures.
If you see alcohol denat., ethanol, or SD alcohol near the top of an ingredient list, it's a red flag for anyone with sensitive or compromised skin.
Fatty Alcohols (Cetyl Alcohol, Stearyl Alcohol, Cetearyl Alcohol)
Safe for most reactive skin.
Despite sharing the name, fatty alcohols are chemically completely different from the ones above. Derived from plant or animal fats, they function as emollients and thickeners and are generally very well-tolerated. If the word before "alcohol" is cetyl, stearyl, or cetearyl, you're looking at a fatty alcohol. Not something to worry about.
Preservatives
Any product that contains water needs a preservative to prevent bacterial and fungal growth. That's legitimate and necessary. The question is which preservatives are safe for reactive skin.
Methylisothiazolinone (MI) and Methylchloroisothiazolinone (MCI)
Best avoided for reactive skin.
MI in particular is something I feel strongly about. It became widely used across leave-on and rinse-off products because it was effective and cheap. It is now known to be highly sensitising and has been linked to a significant rise in contact allergy cases. It has been restricted in leave-on cosmetics in the EU, but it still appears in some rinse-off products and in formulations outside the EU. Avoid it on reactive skin.
Parabens (Methylparaben, Ethylparaben, Propylparaben, Butylparaben)
Use with caution.
Parabens are effective, well-studied preservatives with a long history in cosmetics. The debate around them has been largely driven by concerns about endocrine disruption at high concentrations, and the evidence on topical cosmetic use is genuinely mixed. They are not universally problematic. Some people with reactive skin tolerate them fine; others don't. Worth monitoring if you're trying to identify a trigger.
Phenoxyethanol
Use with caution.
One of the most common paraben alternatives, phenoxyethanol, is generally considered safe at cosmetic concentrations and is significantly less problematic than MI or MCI. Some people with very reactive skin do report sensitivity. It's not a first-line concern, but it's worth being aware of if you've ruled out other triggers.
Formaldehyde-Releasing Preservatives (DMDM Hydantoin, Imidazolidinyl Urea, Quaternium-15)
Best avoided for reactive skin.
These preservatives work by slowly releasing small amounts of formaldehyde. Formaldehyde is a known allergen and sensitiser. They are permitted in cosmetics at low concentrations, but for already-compromised skin, they are an unnecessary risk. Learn these names so you can spot them.
Emulsifiers
Emulsifiers hold water and oil together in creams and lotions. Without them, your moisturiser would separate. Some are well-tolerated; others can cause issues for reactive skin with regular use.
PEG Compounds (PEG followed by a number)
Use with caution.
PEG compounds are widely used and generally considered safe, but they can increase skin permeability with frequent use, allowing other ingredients, including irritants, to penetrate more easily. For very compromised skin, minimising heavy PEG formulations is worth considering.
Polysorbates (Polysorbate 20, 60, 80)
Use with caution.
Derived from sorbitol, polysorbates are used to stabilise and emulsify formulations. Generally well-tolerated, but worth noting if you're trying to track down a reaction and have ruled out more obvious culprits.
Oils and Lipids
For reactive skin, this category matters enormously. The right oils can actively support barrier repair. The wrong ones can clog pores, trap heat, and worsen inflammation. Comedogenic rating, meaning how likely an ingredient is to block pores, is one of the most useful pieces of information you can look up.
Jojoba Oil (Simmondsia Chinensis Seed Oil)
Safe for most reactive skin. Comedogenic rating: 2/5.
Technically, a liquid wax, not an oil. I keep coming back to jojoba because it's one of the most genuinely skin-compatible ingredients I know. It closely resembles the skin's own sebum, absorbs readily without heaviness, and has a long shelf life because it oxidises slowly. It's the kind of ingredient that just gets on with it quietly: no drama, no reaction, consistent support.
It's one of only three ingredients in our Illuminate Face Oil, and the reason it's there is exactly this: when I was formulating for my daughter's skin at its most reactive, jojoba was one of the very few things it accepted without flinching.
Argan Oil (Argania Spinosa Kernel Oil)
Safe for most reactive skin. Comedogenic rating: 0/5.
A comedogenic rating of zero means argan oil is essentially non-pore-clogging, which makes it one of the most reliably safe options for facial use on compromised skin. It's rich in oleic acid, linoleic acid, and vitamin E, and it supports the skin's lipid barrier while remaining lightweight enough not to feel heavy or occlusive. Along with jojoba and vitamin E, it's one of the three ingredients in the Illuminate Face Oil, chosen for its real barrier support without any inflammation.
Rosehip Seed Oil (Rosa Canina Fruit Oil)
Use with caution. Comedogenic rating: 1/5.
Not to be confused with rosehip essential oil, which is a different thing entirely and best avoided on reactive skin. Rosehip seed oil is cold-pressed from the fruit seeds and is rich in linoleic acid and vitamin A precursors. It's generally well-tolerated and often recommended for scarring and uneven skin tone. The caveat is that it oxidises relatively quickly, so freshness and packaging matter. Some people with very reactive skin do report sensitivity.
Coconut Oil (Cocos Nucifera Oil)
Use with caution. Comedogenic rating: 4/5.
I understand why coconut oil became a skincare phenomenon. It's widely available, it feels luxurious, and it has genuine antimicrobial properties. But a comedogenic rating of 4 out of 5 makes it a poor choice for facial use on reactive or acne-prone skin. It can trap heat against inflamed skin, contributing to congestion. For compromised facial skin in particular, there are almost always better-tolerated alternatives.
Shea Butter (Butyrospermum Parkii Butter)
Safe for most reactive skin. Comedogenic rating: 0/5.
A comedogenic rating of zero and a rich fatty acid profile make shea butter one of the more reliable choices for dry, sensitive skin. It provides meaningful emollient and occlusive support and is generally very well-tolerated. If you have a tree nut allergy, patch testing is sensible.
Vitamins and Antioxidants
Vitamin E (Tocopherol)
Safe for most reactive skin.
Vitamin E is the third ingredient in the Illuminate Face Oil, and it earns its place twice over. As an antioxidant, it helps protect the skin from oxidative stress and supports the skin's natural repair processes. And in an oil-based formula, it acts as a natural preservative, preventing other oils from oxidising and extending the product's shelf life without synthetic preservatives.
I use pure tocopherol. It's well-tolerated, well-researched, and does exactly what it needs to do without unnecessary complexity. That's the standard I hold every ingredient to.
Niacinamide (Vitamin B3)
Safe for most reactive skin.
One of the most well-researched skincare actives available. Niacinamide supports barrier function, reduces redness, and has genuine anti-inflammatory properties. All things reactive skin needs. It's generally well-tolerated even on sensitive skin, though concentrations above 10% can occasionally cause flushing. It's worth considering once your skin has stabilised, rather than during an active flare.
Vitamin C (L-Ascorbic Acid and derivatives)
Use with caution on reactive skin.
Vitamin C is one I see cause problems time and again, particularly for women in their forties and beyond who are rebuilding their skincare routine. It is a brilliant antioxidant and brightening ingredient, but pure L-ascorbic acid is acidic, and reactive skin often lets you know about it quickly. If you want to incorporate vitamin C, look for more stable derivatives such as ascorbyl glucoside or sodium ascorbyl phosphate. They are gentler and far less likely to cause a reaction. During a flare, leave it entirely until things have settled. It will still be there when your skin is ready for it.
Humectants
Humectants draw moisture to the skin, either from the environment or from deeper skin layers. They're an important part of keeping reactive skin hydrated without relying on heavy occlusives.
Glycerin (Glycerol)
Safe for most reactive skin.
Glycerin is one of the most effective and well-tolerated humectants available. It's present in the skin's own natural moisturising factor, which is part of why it's so compatible. Unlikely to cause reactions and a genuinely beneficial addition for dry, reactive skin.
Hyaluronic Acid (Sodium Hyaluronate)
Safe for most reactive skin.
Hyaluronic acid holds water and contributes to skin plumpness and hydration. Generally very well-tolerated. One thing worth knowing: in very dry environments, hyaluronic acid can draw moisture from the skin itself rather than from the air. Apply it to damp skin and seal with an emollient or oil to get the most from it.
Label Claims: What They Actually Mean
"If there's one section I wish every person with reactive skin would read and remember, it's this one."
Fragrance-Free
A fragrance-free product means no fragrance ingredients have been added, and this is the claim to look for. It can still carry the natural scent of its ingredients (oils have their own smell) while being genuinely fragrance-free.
Unscented
Unscented does not mean fragrance-free. Products labelled unscented often contain masking fragrances added specifically to neutralise the smell of other ingredients. For reactive skin, unscented is not a safe alternative to fragrance-free. They are not the same thing.
Natural
Unfortunately, the term Natural isn’t regulated, which means any brand can use it, regardless of what's in the formula. What is most important here is that some natural ingredients are genuinely problematic for reactive skin, essential oils being the most obvious example. Some synthetic ingredients are safe, effective, and well-tolerated.
Clean
Also unregulated. "Clean beauty" has no legal definition, and its meaning varies widely across brands and retailers. I understand the appeal of the concept, but I'd encourage you to look past the label claim and read the actual ingredient list. A product can be positioned as clean and still contain essential oils, botanical extracts, and fragrance compounds that reactive skin cannot tolerate.
Hypoallergenic
Not regulated or standardised. There is no agreed-upon testing protocol that a product must pass to use this term. It is a marketing claim, not a guarantee. A hypoallergenic product can still cause reactions.
Dermatologist Tested
A "dermatologist tested" claim tells you a dermatologist tested the product. It tells you nothing about the outcome of that testing. It is one of the weaker claims on a label and should not be taken as an endorsement of safety for reactive skin.
Non-Comedogenic
Non-comedogenic means the product or its ingredients are considered unlikely to block pores. Comedogenic ratings (0 to 5) are the most useful reference, though they were established in animal studies, and individual responses can vary. Ingredients rated 0 to 2 are generally considered safe for reactive and acne-prone facial skin.
One Last Thing About Ingredient Lists
In the UK and EU, cosmetic ingredients are listed in descending order of concentration down to 1%. Anything below 1% can be listed in any order after that point.
What this means in practice: an ingredient near the top of the list is present in a meaningful amount. An ingredient near the bottom - particularly if it's the reason you bought the product - may be present in only trace quantities. "Fairy dusting" is the term for this practice: adding an ingredient for marketing purposes at a concentration too low to do anything useful.
The shorter the list, the more you actually know about what you're applying to your skin. For reactive skin, that clarity isn't a compromise. It's a form of protection.
It's why I built the Illuminate Face Oil around three ingredients. Not because I couldn't add more, but because I didn't need to. Organic jojoba, argan oil, and vitamin E. Every ingredient earns its place. There's nothing to hide behind and nothing to worry about. That's exactly the point.
Have a question about an ingredient not listed here? Get in touch, and I'll add it.
About the Author
Anita Robinson is the Founder and Formulator of Apothecary & Me, a UK natural skincare brand built around minimal, transparent formulations for reactive and compromised skin. Apothecary & Me was created following her daughter's experience of topical steroid withdrawal, a journey that shaped everything about how Anita thinks about ingredients and what belongs on compromised skin.
Disclaimer: This glossary is intended for informational purposes only and does not constitute medical advice. Individual skin responses vary. If you are experiencing a skin condition, please consult a qualified dermatologist or GP. Always patch test new products before use.
