Skin pH and Eczema:
Acidification and the Skin Barrier

Skin pH describes the acidity of the skin’s surface

Atopic dermatitis is an inflammatory form of eczema in which the skin barrier and immune response do not work together normally. Skin pH is one part of that process. It measures acidity at the surface; it does not measure how acidic your blood or whole body is.

On the familiar pH scale, values below 7 are acidic, 7 is neutral under standard conditions, and values above 7 are alkaline. Lower numbers mean greater acidity. Healthy skin is normally mildly acidic, often around pH 4 to 6, with variation between people, body sites, and measurement conditions.^{1, 6}

The acid mantle supports the outer barrier

The acid mantle is the mildly acidic environment at the skin’s surface. The stratum corneum, the outermost skin layer, contains flattened skin cells surrounded by lipids, or fats. These work together to hold water in and limit entry of irritants. Acidity helps regulate the enzymes that maintain this structure.²

There is no single pH number that every person with eczema needs to achieve. A reading can change after washing or applying a product. A product’s pH in its container and the pH measured on your skin are different measurements.^{1, 4}

Higher skin pH can interfere with barrier maintenance

Eczema-prone skin often has a higher pH than healthy comparison skin. “Higher” means less acidic; it does not necessarily mean the skin has become alkaline. Participants in several eczema studies still had average skin readings below 7.^{4, 6}

Enzymes respond to changes in acidity

Enzymes are proteins that speed up chemical reactions. Some help process the lipids between skin cells. Others, called proteases, break down proteins as the outer cells are shed. Experimental research shows that raising skin pH can impair lipid processing and increase protease activity, weakening the connections between cells. Water then escapes more easily.²

Researchers measure this escaping water as transepidermal water loss, or TEWL. A reduction in TEWL can indicate better barrier function, but it is not the same as proving that a treatment prevents flares or controls eczema over the long term.

Filaggrin contributes to acidity, but it is not the only pathway

Filaggrin is a protein involved in building the skin barrier. Its breakdown produces substances that contribute to skin hydration and acidity. Skin also releases fatty acids and uses a transporter called NHE1 to move hydrogen ions, helping create an acidic environment.

In a laboratory model of reconstructed skin, other acidifying pathways partly compensated for reduced filaggrin, yet the barrier still had abnormalities. This helps explain why a normal pH reading alone cannot prove that the barrier is healthy.³ Our eczema genetics guide explains filaggrin and inherited susceptibility in more detail.

Human acidification studies show promise with important limits

Acidification research asks whether a finished skin-care formula can maintain a suitable acidic environment and improve barrier function. The human studies below tested particular moisturizers. Their results cannot automatically be applied to every product labeled “pH balanced.”

These studies support further research into acidifying formulations. They do not establish a universal target pH, show that stronger acidity is better, or justify replacing prescribed eczema treatment. Long-term benefits and tolerability need to be demonstrated for the particular product and population.

Vinegar soaks are not a proven substitute for formulated skin care

Vinegar contains acetic acid, but lowering the pH briefly is not enough to show that a treatment repairs eczema-prone skin.

A 2019 pilot study compared dilute apple cider vinegar with water on opposite forearms in 22 people, including 11 with atopic dermatitis. After two weeks, the researchers found no meaningful improvement in barrier integrity from the vinegar soaks. Sixteen of the 22 participants reported mild side effects, which improved after stopping.⁷

A related report found no significant reduction in Staphylococcus aureus, a bacterium that commonly colonizes eczema-prone skin, and no convincing change in the skin bacterial community with the tested vinegar regimen.⁸

Do not try to reproduce research formulas by adding vinegar, lemon juice, or concentrated acids to a moisturizer or bath. The finished formula, acid concentration, contact time, and condition of the skin all affect tolerability. Burning or persistent stinging is a reason to stop a product and seek advice, not a sign that it is correcting your skin’s pH.

Everyday care supports the barrier without chasing a pH number

Gentle cleansing and moisture come first

Choose a mild, fragrance-free cleanser and use it where needed. Keep baths or showers brief and lukewarm. Gently pat the skin partly dry, then apply a fragrance-free cream or ointment while it is still damp. Reapply moisturizer as needed for dryness.⁹

pH is one feature of a cleanser or moisturizer. The complete formula and your skin’s response matter too. “pH balanced” does not guarantee that a product will suit every person with eczema. Persistent itch, inflammation, or repeated flares need a treatment plan; our eczema flare guide covers that next step.

Daily Wash and Cream support cleansing and moisture

Happy Cappy Daily Shampoo & Body Wash is a pediatrician-designed, dermatologist-tested, hypoallergenic cleanser for dry, sensitive, eczema-prone skin in babies, children, and adults. Its fragrance-free, dye-free formula cleanses hair, face, and body without SLS/SLES. Glycerin, panthenol, and hyaluronic acid help skin feel hydrated; oat kernel extract and aloe help comfort dry skin. Use daily or as often as needed.

Happy Cappy Moisturizing Cream uses glycerin to attract moisture and petrolatum to help retain it. Licorice root extract helps calm the look of redness. Apply the cream as a separate leave-on moisturizing step.

Both finished formulas are described as acidic in our product pH guide.¹⁰ That description does not establish that they deliver the same acidification effects as the research creams above. Their role here is gentle everyday cleansing and moisture alongside any prescribed care.

Explore the Daily Wash and Moisturizing Cream routine