Beta Hydroxy Acid (BHA)

Beta hydroxy acid (BHA) is an oil-soluble exfoliating acid, most commonly salicylic acid, used in skincare to clear and refine the pores. Its defining feature is that, unlike water-soluble AHAs, it can penetrate through sebum into the lining of the pore.

Because it is oil-soluble, BHA works both on the skin surface and inside oil-filled pores, loosening dead cells and helping to dissolve the mix of oil and debris that contributes to clogging. It also has mild anti-inflammatory and calming properties. These traits make it a common choice for oily and combination skin, blackheads, blemishes, and congested or bumpy texture.

Salicylic acid is typically used at around 0.5–2% in leave-on and rinse-off products intended for daily or near-daily use. As with other exfoliating acids, the product's pH influences how effectively it works.

BHA can be drying or irritating if overused, so it is generally introduced a few times a week and adjusted according to tolerance. Excessive or overlapping use with other exfoliants may compromise the skin barrier. A daily sunscreen is advisable while using exfoliating acids.