Understanding pH in Skincare: What Really Matters
What Is pH and Why Should We Care?
pH is a scale ranging from 0 to 14 that indicates how acidic or alkaline a substance is. The skin’s natural pH is around 5.5, which is slightly acidic. Neutral pH refers to a value of 7. When skincare products are overly alkaline or strongly acidic, this balance can be disrupted, potentially leading to dryness, irritation, or breakouts.
The pH Spectrum of Skincare Products
In reality, the pH range of skincare products is narrower than most people assume.
Cleansers are generally alkaline by nature, as their primary function is cleansing—using surfactants to remove impurities from the skin’s surface.
Leave-on products, on the other hand, fall into a neutral to mildly acidic range, contrary to common belief. This applies to toners, serums, and moisturizers alike. With very few exceptions, there is little reason for leave-on products to be formulated with strongly acidic or alkaline pH levels.
Why Leave-On Products Are Neutral to Mildly Acidic
Products such as moisturizers and serums, which remain on the skin after application, are designed to stay close to the skin’s natural pH environment. Deviating from this range may increase the risk of irritation without providing meaningful functional benefits. In addition, a neutral to mildly acidic pH is advantageous for maintaining product stability.
Special-Purpose Products and pH
Some products with specific purposes—such as exfoliating peels—may be acidic. Ingredients like AHA, BHA, and PHA require an acidic environment to function effectively, so these products are intentionally formulated at a lower pH. Pure vitamin C (L-ascorbic acid) is another example. However, such products represent only a small fraction of the overall skincare market.
So why is the phrase “slightly acidic and therefore good for the skin” repeated so often?
Rather than indicating a true functional advantage, it is largely a marketing expression that emphasizes safety using familiar language. What truly matters is not the term “slightly acidic” itself, but which ingredients are used and what purpose the product is designed to serve.