There are several AHAs available in cosmetics — glycolic, lactic, malic, mandelic, citric. Each has a different profile of efficacy, tolerability and speed of action. Lactic acid has the best combination of these three variables for most skin types, especially for those beginning chemical exfoliation.

Why Lactic Acid Is the Ideal Entry AHA

The lactic acid molecule is larger than glycolic acid's — this means more gradual penetration and less irritation risk. This is the variable that makes it more tolerable without sacrificing efficacy:

• Lower risk of erythema than glycolic at equivalent concentrations
• Humectant effect in addition to exfoliation (it's a natural humectant)
• Evidence for hyperpigmentation, fine lines and uneven texture
• Compatible with dry, mature and sensitive skin that doesn't tolerate glycolic

Introduction Protocol

1. Weeks 1–2: 1x/week, at night only, on clean dry skin
2. Weeks 3–4: 2x/week if no reactivity
3. Maintenance: 2–3x/week according to tolerance
4. Always: SPF mandatory the following morning

Incompatibilities to Respect

• Don't combine with retinol/bakuchiol the same night — apply on alternating nights
• Don't combine with pure vitamin C (ascorbic acid) in the same application
• Don't use within 48 hours of waxing or laser treatment