What a chemical exfoliant actually is
The outer layer of your skin is made of dead cells that are held together by a mix of fats and other compounds. Skin sheds these cells naturally, but not always evenly. A chemical exfoliant is an ingredient that helps loosen the bonds between those surface cells so they come away more easily, without you rubbing them off by hand.
The word “chemical” here is not a warning. Water is a chemical too. It simply describes exfoliation that relies on an ingredient, usually a mild acid, instead of grains, beads or a brush.
Chemical versus physical exfoliation
A physical exfoliant works through friction: scrubs with particles, cleansing brushes, rough cloths. A chemical exfoliant works through dissolving and loosening, and you leave it on skin for a while or rinse it off after a short time.
Neither is automatically better. Friction can be uneven, and harsh particles or hard scrubbing can cause tiny surface irritation, especially on the face. Acids can be more even but are easy to overuse, because the effect is not as obvious while you are applying them. Many people with reactive or easily irritated skin find acids or very gentle methods more comfortable than coarse scrubs, though that varies from person to person. If you are using cleansing brushes, they count as physical exfoliation too, so keep that in mind when you add acids.
The three main families
Most chemical exfoliants fall into three groups, and the difference matters for which one suits you.
AHAs (alpha hydroxy acids)
AHAs are water-soluble acids that work mainly on the skin’s surface. Glycolic acid and lactic acid are the best-known examples, and mandelic acid is another. Glycolic acid has a small molecule and is often described as the most potent of the group, which is also why it can be more irritating. Lactic and mandelic acids are typically considered milder choices.
BHAs (beta hydroxy acids)
The BHA you will most often see is salicylic acid. It is oil-soluble, which means it can work inside pores as well as on the surface. That is why it is commonly used for oily or congested skin and for blackheads.
PHAs (polyhydroxy acids)
PHAs, such as gluconolactone, are related to AHAs but have larger molecules, so they tend to penetrate more slowly. They are generally considered gentler, and are sometimes chosen by people with sensitive skin who want to try an acid. They are usually less widely available and the evidence for their benefits is more limited than for AHAs and BHAs.
What they can and cannot do
Used sensibly, chemical exfoliants can make the surface feel smoother, help dull skin look brighter, and may help with rough texture and clogged pores. Over weeks of regular use, some people also notice that uneven tone looks a little more even, particularly where it comes from past marks.
They cannot change your pore size permanently, remove deep scars, or cure acne or skin conditions. Results are gradual and vary a lot between people. Anything that looks like a skin disease rather than simple dullness is better looked at by a professional.
Formats and strength
Chemical exfoliants come as toners, serums, gels, pads, masks and washes. Leave-on products are in contact with skin longer, so they tend to feel stronger than a wash at the same percentage. The percentage on the label is only part of the story. The formula’s acidity (see skin pH for why that matters) and the other ingredients both affect how it behaves, so a lower number is not always gentler.
Rinse-off products and weaker leave-ons are a sensible starting point. Face toners that contain acids are a common entry point, but they are not the same as a plain, non-exfoliating toner, so read what the product contains.
How to start
- Do a patch test first. Our guide to patch testing covers how to do it on a small area.
- Begin with one product, once or twice a week, at night or at a time you are not heading into strong sun.
- Watch your skin for a couple of weeks before increasing. Mild tingling can happen; stinging, burning or lasting redness is a sign to stop.
- Keep the rest of the routine simple: a gentle cleanser, a moisturizer, and sunscreen in the morning.
- Add new products one at a time. Introducing products slowly makes it much easier to tell what is causing a reaction.
Sun and other actives
Exfoliating acids, especially AHAs, can make skin more sensitive to sun for a period of time. Daily sunscreen matters when you use them, and it is worth reading sunscreen basics if you do not already use one regularly.
Be careful about mixing actives. Combining several exfoliating acids, or an acid with retinol products, in one routine is a common route to irritation. Many people alternate nights or use them on separate days.
Signs to pull back
Stop or cut back if skin feels tight, shiny, burning, or suddenly reactive to products it used to tolerate. These can be signs of skin over-exfoliation or a stressed skin barrier, and the usual approach is to pause acids and keep to gentle basics until skin settles.
If you have eczema, rosacea, an open wound, a rash that is spreading, or irritation that does not improve, talk to a doctor or pharmacist before using exfoliating acids. For anything persistent, painful, or changing, a qualified health professional is the right person to ask.