Lactic Acid 5% + HA is a mild alpha hydroxy acid solution that offers gentle yet effective exfoliation targeted at the skin's surface. It is supported with purified Tasmanian pepperberry extract , which has been shown to reduce irritation and sensitivity that can be associated with acid use. This water-based serum is ideal for dry and sensitive skin. This pH of this formula is approximately 3.8. Lactic Acid has a pKa of 3.8 and pKa is the most important aspect to consider in formulating with acids. pKa implies acid availability. When pKa is close to pH, there is an ideal balance between salt and acidity, maximising effectiveness of the acid and reducing irritation.