AHAs and BHAs: The Acids That Actually Do Something

Chemical exfoliants work at a molecular level to dissolve the bonds holding dead skin cells together. They don't scrub. They dissolve. And that distinction matters more than most people realize.

AHAs: Alpha Hydroxy Acids

Glycolic Lactic Mandelic

AHAs are water soluble acids that work on the skin's surface. They dissolve bonds between dead cells so they shed more efficiently, revealing brighter, smoother skin.

Glycolic acid has the smallest molecular size, it penetrates most deeply and works fastest. Most potent and most studied, but also most likely to cause irritation.

Lactic acid is gentler and also a humectant, drawing moisture into the skin as it exfoliates. For dry or dehydrated skin, it's particularly intelligent.

Mandelic acid has the largest molecular size, producing the gentlest effect. Especially well suited to sensitive skin and darker skin tones, with significantly lower risk of triggering post inflammatory hyperpigmentation.

AHAs increase photosensitivity. Use at night and always follow with SPF.

BHAs: Beta Hydroxy Acids

Salicylic Acid

Where AHAs work on the surface, salicylic acid goes deeper. As an oil soluble acid, it penetrates into the pore lining, dissolving sebum, dead cells, and debris. It also has meaningful anti inflammatory properties.

For acne prone or chronically oily skin, it's often the most impactful single active. Effective at 0.5 to 2%. Two to three times per week is generally sufficient.

Which One Is Right for You?

For oily or acne prone skin, a BHA is often a good starting point, with a gentle AHA added on alternate evenings once the skin has adjusted.

For dry or dehydrated skin, lactic acid tends to be a gentler starting point because it hydrates while it exfoliates.

For combination skin, many find benefit in using both on different days, a BHA for T-zone pores, a lactic or mandelic for tone elsewhere.

For sensitive or darker skin tones, mandelic acid is typically the most forgiving entry point.

One consistent rule: do not layer multiple exfoliating acids in the same routine. Choose one per session.