Salicylic (BHA) or Glycolic (AHA) Acid: Which for Breakouts, Which for Dark Spots?

Skincare acids are like tools in a toolbox: they all "exfoliate," but each is built for its own job. Mix up BHA and AHA and you'll spend months treating pimples with a pigmentation product, wondering where the results went.

How it works

BHA is a bottle brush for pores. Salicylic acid is oil-soluble: instead of sitting on the surface, it dives into a sebum-filled pore and dissolves the plug from within. It also calms inflammation — it's a relative of aspirin. That's why blackheads, under-the-skin bumps and oily shine answer to BHA.

AHA is an eraser for the surface. Glycolic acid (and its gentler sister, lactic) is water-soluble and doesn't travel into pores. What it does brilliantly is un-glue dead surface cells: skin renews faster, dark spots fade, dullness lifts, fine lines soften. Glycolic is the smallest AHA molecule — the most penetrating and the most tingly.

Look for in the list: Salicylic Acid (BHA, working range 0.5–2%); Glycolic Acid, Lactic Acid (AHAs, 5–10% in home products). The higher in the list, the more serious.

Don't mix: either acid with retinol on the same night, or with each other when starting out. And both demand morning SPF — no exceptions.

Choose BHA if

• breakouts, blackheads, an oily T-zone;
• pores clog up and "cleanings" last a week;
• your skin is dense and oily.

Choose AHA if

• post-acne marks, pigmentation, uneven tone;
• skin looks dull, "tired," with fine lines;
• dryness with flaking — lactic acid also hydrates.

Common mistake. Using both acids at once "for a double strike." The double strike lands on your skin barrier: irritation, flaking, redness. Alternate days, or pick one for your main concern — that's plenty.

Fun fact: humanity used AHAs long before dermatologists: Cleopatra's milk baths were lactic acid, and the grape treatments of French queens were tartaric.