Lactic Acid.

What it does

Benefits

• Exfoliates to smooth rough texture, refine pores, and brighten dull, uneven tone
• Doubles as a moisturizer because it is a humectant that boosts skin hydration (a 12% prescription form, LacHydrin, is FDA-approved for dry skin)
• Larger molecule than glycolic acid means slower, gentler penetration, making it a good first AHA for newcomers and sensitive skin
• With regular use can soften the look of fine lines and support a healthier-looking surface

Side effects

• Can cause stinging, tingling, redness, or dryness, especially at higher strengths or low pH
• Increases the skin's sensitivity to the sun and the risk of sunburn, so daily broad-spectrum sunscreen is essential during use and for about a week after
• Over-exfoliation can compromise the skin barrier

Who it's for

First-time acid users and people with dull, dry, or uneven skin who want gentle exfoliation plus hydration

Who should be careful