Reference
The most confused skincare terms, untangled
Skincare has a lot of words that look like each other and mean different things. Some of that is chemistry doing its job. Some of it is marketing counting on you not to look. Here are 23 of the ones people mix up most, each in a single plain paragraph, with the pages to read next.
Every entry is built from our ingredient knowledge base, so it follows the data rather than a copywriter. How we score sets out the method.
Words on the label
The terms that sound like a promise and are not always one.
AHA BHA
Both are chemical exfoliants, and the difference is simply what they dissolve in. AHAs are water-loving and work on the surface, loosening dead cells so skin looks brighter and smoother. BHAs are oil-loving, so they get down inside a pore and clear it out, which is why they suit blackheads and oily skin. In our glossary the AHAs include Glycolic acid, Lactic acid and Mandelic Acid, and the BHA side is Salicylic acid (BHA). Neither is stronger as a category: the concentration and the formula decide that.
Fragrance-free Unscented
These sound identical and are not. Fragrance-free means no fragrance was added. Unscented means the product is not meant to smell of anything, which is sometimes achieved by adding a masking fragrance to cover the raw smell of the base. So an unscented product can still contain fragrance, and a fragrance-free one should not. If your skin is reactive, read the ingredient list rather than the front of the bottle: Benzyl Alcohol, Madecassoside and Fragrance are examples of what to look for.
Non-comedogenic What it actually promises
"Non-comedogenic" is a marketing term, not a regulated one. No authority tests it and no brand has to prove it, so it means whatever the company decides it means. What does exist is a published 0 to 5 comedogenic scale from old lab tests on isolated ingredients, and we carry that rating for 35 ingredients, with Coconut Oil, Isopropyl Myristate and Isopropyl Palmitate among the highest rated. Treat it as a flag worth noticing if you clog easily, not a verdict: how much is used and what it is mixed with matter more than the number.
Hypoallergenic What it actually promises
Another word with no legal definition behind it. It suggests a product is less likely to cause a reaction, but there is no standard test it has to pass and no list of ingredients it has to leave out. Your own skin is the only reliable test, which is what a patch test is for. What we can tell you is which ingredients are known to irritate more often, such as Tretinoin, Benzoyl Peroxide and Glycolic acid, and you can check any of them by name.
Dehydrated skin Dry skin
Dry skin lacks oil, and it is a skin type you are largely born with. Dehydrated skin lacks water, and it is a temporary state that oily skin gets too. The fix differs: dehydrated skin wants humectants that pull water in, while dry skin wants the oils and lipids that stop water leaving. On the humectant side we have Glycerin, Crosslinked sodium HA and Hyaluronic acid; on the oil and barrier side, Ceramide 3, Petrolatum and Argan Oil. Most people who think they are dry are some of both, and a routine with one of each is usually the answer.
Ingredients that look alike
Two names a letter apart, doing measurably different things.
Isopropyl Palmitate Isopropyl Myristate
Two near-identical ester emollients. Myristate is the lighter one and rates a little higher for clogging pores.
Retinyl Palmitate Retinol
Retinyl palmitate is the gentlest, weakest retinoid; your skin converts it into retinol, so it does less and works more slowly. Retinyl Palmitate is the gentler of the two, at low irritation risk against high for Retinol.
Retinol Retinal
Retinal sits one conversion step closer to the active form than retinol, so it tends to work a little faster. Retinal is the gentler of the two, at moderate irritation risk against high for Retinol.
Retinol Tretinoin
Tretinoin is the prescription acid form that works right away. Retinol is the gentler over-the-counter version your skin has to convert first.
Retinol Adapalene
Adapalene is a prescription-grade retinoid built to be more stable and less irritating than the older ones. Adapalene is the gentler of the two, at moderate irritation risk against high for Retinol.
Cetyl Alcohol Cetearyl Alcohol
Cetearyl alcohol is simply a blend that includes cetyl alcohol. Both are waxy, conditioning fatty alcohols, not the drying kind.
Cetearyl Alcohol Stearyl Alcohol
Both are gentle fatty alcohols used to thicken and soften. Cetearyl is a blend; stearyl is one of its parts.
Cetyl Alcohol Denatured Alcohol
Same word, opposite jobs. Cetyl is a waxy, conditioning fatty alcohol; denatured alcohol is the fast-drying solvent kind. Cetyl Alcohol is the gentler of the two, at low irritation risk against high for Denatured Alcohol.
Glycolic acid Lactic acid
Both are AHAs. Glycolic is the smaller molecule that gets in deeper and stronger; lactic is gentler and also hydrates. Lactic acid is the gentler of the two, at moderate irritation risk against high for Glycolic acid.
Salicylic acid (BHA) Glycolic acid
Salicylic is oil-loving and works inside the pore (a BHA). Glycolic works on the surface (an AHA). Salicylic acid (BHA) is the gentler of the two, at moderate irritation risk against high for Glycolic acid.
Hyaluronic acid Polyglutamic Acid
Both are humectants that pull in water. Polyglutamic acid holds even more and sits on top; hyaluronic draws moisture in. Hyaluronic acid has the stronger evidence behind it (strong, against emerging for Polyglutamic Acid).
Kojic Acid Alpha Arbutin
Both fade dark spots by slowing pigment. Arbutin is the gentle everyday option; kojic is stronger but more likely to irritate.
Mineral Oil Petrolatum
Same inert, non-reactive source. Petrolatum is the thick jelly that seals; mineral oil is the pourable liquid version.
Vitamin C (LAA) THD Ascorbate
Pure vitamin C is the strongest but least stable. THD ascorbate is an oil-loving derivative that trades some punch for a gentler, steadier feel. THD Ascorbate is the gentler of the two, at low irritation risk against moderate for Vitamin C (LAA).
Vitamin C (LAA) Ferulic Acid
Ferulic acid is not a vitamin C. It is an antioxidant added to steady a vitamin C formula and make it work harder. Ferulic Acid is the gentler of the two, at low irritation risk against moderate for Vitamin C (LAA).
Vitamin B3 Pro-vitamin B5
Different vitamins. Niacinamide is B3, a multitasker for tone and oil; panthenol is pro-B5, a soother and hydrator. Pro-vitamin B5 is the gentler of the two, at low irritation risk against moderate for Vitamin B3.
Benzoyl Peroxide Salicylic acid (BHA)
Both fight breakouts, differently. Benzoyl peroxide kills acne bacteria; salicylic acid unclogs the pore. Salicylic acid (BHA) is the gentler of the two, at moderate irritation risk against high for Benzoyl Peroxide.
Bakuchiol Retinol
Bakuchiol is a plant ingredient sold as a natural retinol alternative. It is gentler, but it is not a true retinoid and works differently. Retinol is the one to avoid in pregnancy.
Found one we have missed? The glossary carries a page for every ingredient we know, and the conflict checker answers the other common question: whether two of them can be used together.
General guidance, not medical advice. Here is when to see a dermatologist instead.