What is the pH range of the Stratum Corneum?

• A. 7 to 8
• B. 4 to 5.5
• C. 3 to 4
• D. 6 to 7.5

Answer: (B)

The Stratum Corneum relies on a mildly acidic environment, often called the acid mantle, to keep the skin barrier functioning well. This environment is typically around 4 to 5.5, which supports the enzymes that regulate desquamation and lipid processing, helps maintain the orderly structure of lipids and corneocytes, and strengthens antimicrobial defenses. When the pH shifts toward alkaline (for example around 7–8), barrier lipids can become destabilized, enzyme activity becomes less optimal, and irritants or microbes can penetrate more easily. A pH range that’s far more acidic (3–4) is not typical for healthy skin and can be irritating, while a near-neutral range (6–7.5) does not provide the optimal acidic conditions that support barrier health.