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 the most effective categories of exfoliating ingredient available in professional skincare. They're often discussed together, but they work differently, suit different skin types, and shouldn't be chosen interchangeably. Understanding the distinction is worth the few minutes it takes.

1. What AHAs Do

Alpha hydroxy acids — glycolic acid, lactic acid, mandelic acid, and others — are water-soluble acids that work on the skin's surface. They dissolve the bonds between dead skin cells, encouraging them to shed more efficiently and revealing the fresher, smoother skin underneath. Glycolic acid is the smallest molecule in the group, penetrates deepest, and is most effective for texture and fine lines. Lactic acid is gentler and more hydrating, better suited to dry or sensitive skin. Mandelic acid is the largest molecule, penetrates most slowly, and is often recommended for darker skin tones due to its lower risk of causing post-inflammatory hyperpigmentation.

2. What BHAs Do

Beta hydroxy acids — primarily salicylic acid — are oil-soluble. This is the critical distinction. Because salicylic acid can penetrate through sebum, it works inside the pore rather than just on the surface. It dissolves the mixture of oil and dead skin cells that causes congestion, blackheads, and acne breakouts from within the follicle. For oily, acne-prone skin, salicylic acid is significantly more relevant than AHAs for addressing the root cause of breakouts, rather than simply improving surface texture.

3. How to Choose Between Them

The decision mostly follows skin type and primary concern. If your main concern is texture, fine lines, dullness, or pigmentation, and your skin is relatively normal to dry, an AHA is the right starting point. If your skin is oily, prone to congestion, breakouts, or blackheads, a BHA addresses those concerns more directly. If your skin is both acne-prone and textured — common in adult acne — combination products that include both can be appropriate, though careful introduction is essential to avoid over-exfoliation.

4. How Often to Use Them

More is rarely better with chemical exfoliants. For most people, two to three times per week is sufficient to see real improvements without compromising the skin barrier. Daily use of high-concentration acids is a common cause of the very sensitivity and redness people try to use acids to address. Always follow acid use with an SPF the following morning — exfoliating acids increase photosensitivity meaningfully, and sun exposure on freshly exfoliated skin accelerates pigmentation rather than reducing it.

Both AHAs and BHAs are genuinely effective when chosen correctly and used with appropriate frequency. The most common mistake is using the wrong one for your skin type, or using either one too often. At Skintique, we stock professional exfoliating formulations from AlumierMD and iS Clinical that are formulated to deliver real results without unnecessary barrier disruption — and we can help you identify which approach is right for your skin.