AHAs and BHAs: What They Do, How They Differ, and Which One Your Skin Needs

Alpha hydroxy acids and beta hydroxy acids are two of skincare's most useful exfoliating ingredients. People tend to lump them together. They shouldn't. The two work in different ways, suit different skin, and swapping one for the other can leave you with a product that does very little for your particular concern. A few minutes getting the difference straight is worth it.

1. What AHAs Do

Alpha hydroxy acids, glycolic acid, lactic acid, mandelic acid and the rest, are water-soluble and do their work on the surface of the skin. They loosen the bonds holding tired, dead cells in place, so those cells shed more easily and the fresher skin below comes through. Glycolic is the smallest molecule of the bunch, so it sinks in furthest, and it tends to be the one people reach for when texture and fine lines are the issue. Lactic acid is softer and more hydrating, which makes it a better fit for dry or sensitive skin. Mandelic is the largest molecule, so it moves in slowly, and it's often suggested for deeper skin tones because it carries a lower risk of leaving marks behind after inflammation.

2. What BHAs Do

Beta hydroxy acids, mainly salicylic acid, are oil-soluble, and that one property changes everything. Because salicylic can move through sebum, it gets down into the pore rather than staying up top. Inside the follicle it breaks down the plug of oil and dead skin that shows up as congestion, blackheads and blemishes. So if your skin runs oily and breaks out, a BHA speaks to what's actually going on far more directly than an AHA, which mostly smooths the surface.

3. How to Choose Between Them

Mostly this comes down to your skin type and what's bothering you most. Normal to dry skin dealing with rough texture, fine lines, dullness or pigmentation? An AHA is the sensible place to begin. Oily skin prone to congestion, spots or blackheads? A BHA goes straight at it. And plenty of people, particularly with adult acne, have both texture and breakouts at once. Formulas that pair an AHA and a BHA can suit that, as long as you bring them in slowly. Pile them on and you'll tip over into over-exfoliation.

4. How Often to Use Them

With acids, more is rarely better. Two or three times a week does the job for most people, enough to see a real difference without wearing down the barrier. Reaching for a high-strength acid every single day is one of the most common reasons skin ends up red and touchy, which is usually the very thing people bought the acid to sort out. And whatever you use, follow it with SPF the next morning. Exfoliating acids leave skin noticeably more sensitive to daylight, and sun on freshly exfoliated skin drives pigmentation rather than fading it.

Used well, and on the right skin, both AHAs and BHAs earn their place. The usual slip-ups are simple: the wrong acid for your skin type, or the right one used far too often. At Skintique we stock professional exfoliating formulas from AlumierMD and iS Clinical that are built to work without roughing up the barrier, and we're happy to help you work out which route suits your skin.