Salicylic acid is the ingredient most people reach for when their skin looks congested – and the one most often used incorrectly, usually by applying too much, too often, to skin that didn't need it. Here's what makes it different from the other acids, and how to get it right.
Why oil-solubility matters
Almost every other exfoliating acid is water-soluble, so it works across the surface of the skin. Salicylic acid is oil-soluble, which means it can mix with the sebum in a pore rather than sitting on top of it. That single property is why it behaves so differently, and why it's the acid associated with skin that looks shiny, rough or visibly congested.
Technically it's a beta hydroxy acid (BHA) — the only one in common cosmetic use, which is why "BHA" and "salicylic acid" are used almost interchangeably on packaging. It also has a naturally calming character on the skin's surface, which is part of why it tends to be better tolerated than its strength suggests.
What it's used for
In cosmetic terms, salicylic acid is chosen for the appearance of blocked-looking pores, the look of blackheads, uneven surface texture and excess shine. Skin often looks clearer and more refined with consistent use, and makeup tends to sit better on a smoother surface.
If you're dealing with a diagnosed skin condition rather than the occasional congested patch, that's worth discussing with your GP or a dermatologist — a cosmetic exfoliant and a medical treatment are different things, and it's worth knowing which one you actually need.
Percentage and format
Most cosmetic products sit between 0.5% and 2%, and 2% is the practical ceiling over the counter. But the format matters at least as much as the number:
- Cleansers — brief contact, then rinsed off. The gentlest way to use it, and a sensible starting point.
- Toners and liquid exfoliants — leave-on, spread across the whole face. Good for general congestion and texture.
- Serums and targeted gels — the most concentrated contact, best used on specific areas rather than everywhere.
A 2% cleanser is a much gentler proposition than a 2% leave-on serum, even though the number is identical.
How to use it
Start two or three times a week rather than daily, and use it in the evening. Watch for the classic sign of overuse: skin that feels tight and looks dull or papery rather than clearer. Salicylic acid is drying by nature, so pair it with a proper moisturiser — hyaluronic acid, ceramides or squalane all work well alongside it.
Keep it separate from retinol while you're building tolerance — alternate nights rather than layering. And wear daily SPF: exfoliated skin is more sensitive to sunlight.
One caution worth knowing: salicylic acid is related to aspirin. If you're allergic to aspirin or salicylates, avoid it, and check with a pharmacist if you're unsure. It's also usually advised to avoid it in pregnancy — speak to your GP or midwife.
Salicylic or an AHA?
Choose salicylic if your skin runs oily or looks congested. Choose an AHA like glycolic or lactic acid if your concern is surface dullness, roughness or the look of fine lines on drier skin. Plenty of people use both — just not on the same night.
Explore our salicylic acid skincare, or see all active skincare.