Salicylic Acid

Salicylic acid is a beta hydroxy acid — on a label it appears as Salicylic Acid, and in Korean product names it is usually shortened to BHA.

Why people reach for it. Usually for clogged pores, blackheads, rough texture and skin that breaks out. Dermatology references describe it as oil-soluble, which is the difference that matters: unlike water-soluble acids it can work inside the pore rather than only on the surface.

It goes by more than one name on a label. Besides Salicylic Acid you will meet Betaine Salicylate and Capryloyl Salicylic Acid. Betaine salicylate is what you get when salicylic acid reacts with betaine, and the commonly cited rule of thumb is that it is about twice as gentle — roughly 4% of it behaves like 2% salicylic acid.

How much. In cosmetics it is normally used at low single-digit percentages: Dr.Ceuracle states 0.5% BHA for its ampoule, Celimax 0.45% for its toner pad. A bigger number does not automatically mean a better product — the pH of the formula and what the acid is paired with matter as much as the percentage itself.

How it fits a routine. Evening use, introduced gradually — every other night at first — and sunscreen the next morning. It is not combined with several other acids or with a retinoid in the same evening without a reason; manufacturers of these products usually say so on the packaging.

In Korean products salicylic acid rarely works alone: it is commonly paired with centella, panthenol or heartleaf, which are there to keep the formula gentle.