Skin pH

Skin pH refers to how acidic or alkaline the surface of the skin is, measured on a scale from 0 to 14 where 7 is neutral. Healthy skin surface pH is generally cited as being slightly acidic, roughly in the region of 4.5 to 5.5, maintained largely by the acid mantle.

This mild acidity supports several functions at once. It helps keep barrier lipids well organised, activates the enzymes that regulate orderly shedding of surface cells, and favours a balanced skin microbiome over some unwanted bacteria. A more alkaline surface, by contrast, is associated with a weaker barrier and greater reactivity, which is why abrupt pH shifts can leave skin feeling tight or irritated.

Product pH is the practical takeaway. Traditional high-pH soaps can push the surface toward alkalinity, so gentle, appropriately buffered cleansers are usually preferred. Acidic exfoliants such as AHAs and BHA are formulated at a low pH because they need it to work, but this also means they should be used measuredly to avoid over-stripping. Skin generally re-establishes its natural pH over time on its own; supporting rather than repeatedly disrupting that process is the guiding idea.