Glycolic or Lactic Acid?

Should I use Glycolic Acid or Lactic Acid?

Both glycolic acid and lactic acid are AHAs (alpha hydroxy acids), and they are water-soluble, which means they don’t have to be mixed in an oil-based carrier, which is a good thing for those who have problems with oils.

Both glycolic acid and lactic acid are great for exfoliation, but there is one property that really makes one of these products better suited to some skin types and skin-care needs: molecular size.

Glycolic Acid
Yes, size matters when it comes to AHAs. Glycolic acid has a smaller sized molecule, which allows glycolic acid to penetrate more quickly than lactic acid, but this can cause more inflammation and irritation if not used properly. Faster penetration doesn’t necessarily mean deeper penetration. The molecular size doesn’t mean that the glycolic acid will penetrate deeper; you’ll have to leave it on longer to get deeper penetration, but watch out for irritation if you do. Glycolic acid has strong stripping properties, so it’s good for those with oily skin, but it can potentially dehydrate drier skin types—or patches of skin if you’re combination. If you have oily or acne-prone skin, glycolic acid will be the better choice for you.

Lactic Acid
Lactic acid’s larger molecular size means that it sits on your skin longer before being able to penetrate, which reduces irritation, redness, and inflammation. Lactic acid is also a natural humectant, so it will help your skin retain its moisture. Lactic acid is also a natural skin constituent, so it also helps protect the acid mantle and is more biocompatible with our skin. The bottom line: if you have dry or sensitive skin, lactic acid may be a better choice for you.