Four categories remain consistently troublesome for sensitive skin: fragrance, harsh surfactants, alkaline cleansers and harsh preservatives. If your skin barrier is already struggling because your skin is reactive, you can steer clear of these irritants by finding them on an ingredients panel within seconds — once you know what the names look like. The hard part is that many irritants don't honestly announce themselves on products, so you need to learn the INCI names to properly avoid them.
This article is the long version of our Possibly Problematic™ list: what the evidence says about irritants and how to spot them yourself.
Why does sensitive skin react to things other skin tolerates?
Because the barrier that normally holds irritants at the surface has been worn down, and a worn-down barrier is far less selective about what it lets through.
Barrier impairment is one of the recognised features of sensitive skin.1 A healthy barrier is selective — it lets through what your skin can use and holds irritants at the surface. When it has been worn down, the sorting gets less precise, and ingredients that most people never notice start to register.
Your skin surface is also slightly acidic, on average below pH 5,2 and that acidity is part of how the barrier works. It is also one of the conditions your resident bacteria need in order to stay balanced.
The same ingredient can be fine on you in January and a problem in July. And the dose matters — for irritation, less of something, less often, on a barrier that has had time to recover, is often enough. (Allergy behaves differently; we've covered the distinction in why skin suddenly starts reacting to everything.)
Fragrance and essential oils
The single most irritating thing you can put on sensitive skin, and it gets worse the longer the bottle is open.
Fragrance terpenes such as linalool and limonene are even more allergenic as they age. Exposed to air they oxidise into compounds that are among the most frequent causes of fragrance contact allergy.3,4 The product ages on your shelf and the risk rises rather than falls — which is why something you used previously without irritation can turn on you with no warning at all.
Two things make this harder than it should be. "Fragrance free" is not a regulated claim, and fragrance components turn up regularly in products marketed safe for sensitive skin. The terpenes are usually declared individually rather than under the word fragrance, so a panel can look 'fragrance free' at a glance, but in the ingredients panel they are sneakily tucked away in their INCI names.
On a label: fragrance, parfum, aroma — and also limonene, linalool, citronellol, geraniol, eugenol, citral. The second group is often the one people miss and are left confused as to why they are reacting to a product they thought was 'fragrance free'.
Sulphates
Foam is the giveaway, and the foam is the part doing the damage.
Sulphates exist to create lather. Harsher surfactant systems produce higher trans epidermal water loss than milder ones5 — meaning more of your skin's own water escapes afterwards, which is the standard measure of a barrier that has been stripped. Sodium lauryl sulphate is the most studied of them, and it is used in research precisely because it reliably irritates: it is a standard agent for inducing barrier damage in experiments.
On a label: anything ending in -sulfate. SLS, sodium lauryl sulfate, SLES, sodium laureth sulfate. Not to be confused with the many good ingredients that begin with sodium.
Cleanser pH
Separate from the surfactant question, and the easiest thing on this list to change today.
Skin sits between pH 4 and 6. Traditional soap sits between 8.5 and 11. Synthetic detergent cleansers — syndets — sit between 5.5 and 7, with some newer ones at 5.0 to 5.5.5
What alkalinity does is mechanical. Above pH 8, skin proteins swell measurably. Fatty acids in the lipid bilayers ionise, which destabilises them. A single soap wash removes more cholesterol and more water-soluble protein than a syndet wash does, and repeated soap washing damages both the protein and lipid regions of the stratum corneum, while syndet-washed skin keeps them largely intact.5
A cleanser can be gentle on pH and harsh on surfactant, or the reverse — they are independent. And the cleanser is the product with the most leverage over your skin, because you use it most often and it is the only one designed to remove things. Our Get Fresh Calming Cleanser, is built around a Lactobacillus/aloe vera leaf juice ferment rather than a foaming system.
On a label: a true soap names itself as a saponified oil — sodium palmate, sodium cocoate, sodium tallowate, sodium olivate. If those sit near the top of a cleanser's panel, you are washing with soap no matter what the front of the tube says.
Harsh preservatives
Not all preservatives are equal, and the harsher ones are among the more common irritants for reactive skin.
Every water-based product needs preserving — an unpreserved one is a contamination risk — so the question is never whether to preserve but what with. Phenoxyethanol, sodium benzoate, parabens and ethylhexylglycerin can be very irritating on sensitive skin.
We use a water-based preservation system instead, which holds a long shelf life while staying gentle.
On a label: phenoxyethanol, sodium benzoate, ethylhexylglycerin, and anything ending in -paraben.
What else is on the list, and why
| Category | What it does | On a label |
|---|---|---|
| Drying alcohols | Keep a formula stable, and strip and aggravate while they do it | Alcohol denat., ethanol, SD alcohol, isopropyl alcohol |
| Silicones | Trap oil and debris, and tend to clog pores | Anything ending -cone, -siloxane, -silanol |
| Dyes | No skin benefit at all; they exist to give a product colour | CI plus five digits, FD&C, D&C, Lake |
Two letters and a number is a colour. Anything ending in -cone is a silicone. The naming conventions do a lot of the work once you know how to look for them.
Do these ingredients damage the skin microbiome too?
Some of the evidence points that way, and it is worth being straight about how far it goes.
An acidic skin surface helps resident organisms like Staphylococcus epidermidis stay attached. An alkaline one encourages them to disperse, and the swelling that comes with it may make it easier for transient organisms to take hold.5 So the cleanser pH question is a barrier question and a microbiome question at once.
Preservatives are less settled. One study tested twenty-two preservative ingredients in combination against bacteria grown on a skin model, including phenoxyethanol, sodium benzoate and ethylhexylglycerin: some combinations suppressed Staphylococcus aureus while leaving S. epidermidis alone, and others strongly inhibited S. epidermidis — the organism you want to keep.6 Separate in-vivo work on four finished formulations found no significant change in microbiome diversity over five weeks, though it had no preservative-free control.7 Both studies were industry-funded, which is worth taking into account.
There’s also no reference range for a healthy skin microbiome, and no test that’ll tell you whether yours has changed. Nobody can make an honest promise to rebalance it — so we don’t make one.
Eliminating irritants out of your skincare routine is the easiest and most effective way to support sensitive skin.
What does the most damage?
Ingredients, routines, and product marketing.
| Why it matters | |
|---|---|
| Washing too often, too hot | Every wash removes lipids. Frequency and temperature compound even if you are using a great cleanser. It's not necessary to wash more than 2-3 times in 24 hours. |
| Over-exfoliating | Acids and scrubs take away the surface that your bacteria needs to stay balanced |
| Too many actives at once | Each one is a variable, and together they are adding load to a barrier ready to be disrupted |
| Letting skin recover | Adding too many new products at once can make your skin barrier irritable |
| Trusting the front of the pack | "Gentle", "for sensitive skin" and "fragrance free" are not regulated claims. The ingredient panel is, which is why it's so important to know the INCI names |
What we do, and why it suits sensitive skin
Premium formulas, built through fermentation, and every irritating ingredient left out.
Bio-fermentation is our superpower. A plant material is the prebiotic, a Lactobacillus strain is the probiotic, and the postbiotic is what the two produce together — the fermented material itself, along with the inactivated cells and their components.8 The postbiotic is what goes into the bottled formula. Nothing in it needs to be alive to work, which is how it happily lives on your bathroom shelf.
Our Get Fresh Calming Cleanser provides a gentle yet effective clean whilst maintaining hydration, the High Achiever Super Serum with licorice, papaya and pineapple ferments alongside 4% niacinamide for smoother skin, and the Let's Start Over Barrier Repair Soufflé with squalane and a three-ceramide complex for skin that is very sensitive and in need of repair.
All of our products are void of fragrance, dyes, drying alcohols, essential oils, silicones, parabens, sulphates and harsh preservatives. Taking the irritants out and formulating through bio-fermentation is why our products are consistently loved by our sensitive skin customers who come back again and again.
Where to start
Not sure what your skin needs? The Skin Quiz takes 60 seconds and asks about how your skin is currently behaving.
Or have a look at the bio-fermented skincare range — made in Australia for skin that reacts to everything, with our six week guarantee.
SKINPOSSIBLE™ is an Australian skincare brand formulating pre-, pro- and postbiotic products for sensitive skin, founded in Melbourne by Jade Williams.
This article is general information about cosmetic skincare and is not medical advice. If your skin is painful, broken or not improving, see a GP or dermatologist.
References
- Misery L, Weisshaar E, Brenaut E, et al. Pathophysiology and management of sensitive skin: position paper from the special interest group on sensitive skin of the International Forum for the Study of Itch (IFSI). Journal of the European Academy of Dermatology and Venereology. 2020;34(2):222–229. doi:10.1111/jdv.16000
- Lambers H, Piessens S, Bloem A, Pronk H, Finkel P. Natural skin surface pH is on average below 5, which is beneficial for its resident flora. International Journal of Cosmetic Science. 2006;28(5):359–370. doi:10.1111/j.1467-2494.2006.00344.x
- Bråred Christensson J, Andersen KE, Bruze M, et al. Air-oxidized linalool: a frequent cause of fragrance contact allergy. Contact Dermatitis. 2012;67(5):247–259. PMID 22906042
- Karlberg AT, Dooms-Goossens A. Contact allergy to oxidized d-limonene among dermatitis patients. Contact Dermatitis. 1997;36(4):201–206.
- Mijaljica D, Spada F, Harrison IP. Skin cleansing without or with compromise: soaps and syndets. Molecules. 2022;27(6):2010. doi:10.3390/molecules27062010
- Pinto D, Ciardiello T, Franzoni M, Pasini F, Giuliani G, Rinaldi F. Effect of commonly used cosmetic preservatives on skin resident microflora dynamics. Scientific Reports. 2021;11:8695. doi:10.1038/s41598-021-88072-3
- Murphy B, Hoptroff M, Arnold D, Eccles R, Campbell-Lee S. In-vivo impact of common cosmetic preservative systems in full formulation on the skin microbiome. PLOS ONE. 2021;16(7):e0254172. doi:10.1371/journal.pone.0254172
- Salminen S, Collado MC, Endo A, et al. The International Scientific Association of Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of postbiotics. Nature Reviews Gastroenterology & Hepatology. 2021;18(9):649–667. doi:10.1038/s41575-021-00440-6
