pH
pH — a measure of how acidic or alkaline a substance is, expressed on a scale from 0 to 14 where 7 is neutral. In skincare it matters because the skin's surface is naturally slightly acidic, and product pH can influence both how a formula performs and how the skin barrier responds.
Key points
- The pH scale runs from 0 to 14, with values below 7 acidic and above 7 alkaline.
- Healthy skin has a naturally slightly acidic surface, often described as the acid mantle, typically around pH 4.5 to 5.5.
- Some active ingredients, such as certain exfoliating acids, are formulated at a lower pH to work effectively.
- Products that are very alkaline can disrupt the skin barrier, which is one reason many cleansers aim for a skin-friendly pH.
Frequently asked
Why does the pH of skincare products matter?
Product pH can affect both how well certain actives work and how the skin barrier responds, since skin is naturally slightly acidic. Formulas that stray too far from skin-friendly levels may cause dryness or irritation.
What is the natural pH of skin?
The skin's surface, sometimes called the acid mantle, is typically slightly acidic, often cited around pH 4.5 to 5.5. This mild acidity helps support the barrier and its protective functions.
Related topics
This is a foundational entry in the SYNC Skin Encyclopedia and is expanded over time. Educational information only — not medical advice.
