A-Z — Acid

Acid —refers to the pH level of a substance, ranging from 0 for the most acidic to 6.9 for the least acidic. Acids are used in cosmetic formulations for a variety of reasons: to neutralize substances that otherwise would be too alkaline for the skin; as active principles that perform a specific function based on their own particular properties (e.g., hyaluronic acid, essential fatty acids); and as exfoliating and peeling agents (e.g., alpha hydroxy acids). Only those acid ingredients with a very low pH will be irritating to the skin because the skin itself is acidic.