Skin pH: Why it is Important?

What is pH?

In chemistry, pH is a measure of the activity of the (solvated) hydrogen ion. p[H], which measures the hydrogen ion concentration.  The scale, devised by a Danish chemist in the early 1900s, ranges from 0, which is the most highly acidic (e.g., battery acid), to 14, which is the most alkaline (e.g., drain cleaner). Seven, the pH of water, is neutral.

Relation between p[OH] and p[H] (red = acid region, blue = basic region)


Why is pH important for the Skin?

Remember that slogan “pH balanced”, that cosmetics companies are always using.  What does it mean? It means that cleansers, toners, astringents, and refresheners pH should be 4.5 – 5.5, since the skin’s pH value is approximately 5.4/5.5.   The human body maintains such a specific balance between acidity and alkalinity.  When the skin’s pH value isn’t what is should be to can cause or exacerbate the following conditions:  dry, rapidly aging skin to acne, and inflammation.  The skin’s barrier, called the acid mantle, which is formed by secretions from the sebaceous glands.  Acts as a barrier to keep lipids and  moisture in and the environmental factors and bacteria out. As the name indicates, the acid mantle is at its strongest and  balanced when the skin is slightly acidic, which is why the skin’s natural pH is 5.4/5.5.  The slight acidity of skin helps to kill bacteria which is why skin that’s too alkaline maybe more susceptible to acne.   An alkaline epidermis tends to be drier and more brittle than an acidic one.  If the acid mantle is not intact this can make skin more sensitive to inflammation and sun damage since the acid mantle isn’t at full strength.  Soaps, especially bar soaps, are very alkaline using them can increase skin alkalinity.  Bars can have a pH of up to 9, leaving an alkaline residue on the skin.

What should I be using?

Look for pH balanced on the label your cleanser (foaming tends to be best for acne-prone skin, while non-foaming or milky for dry skin) or use a litmus strips to test the pH.  Chemical peels, which have an exfoliating effect on the skin can help regulate pH.  These should be left to professionals to preform. When you’re using the right products, the skin’s barrier will always return to its natural, pH.

Some typical pH values




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