Eczema, water and skin pH
- Marcelline Goyen
- Mar 9
- 5 min read
Updated: Mar 10
Table of content
Eczema and Water: Why Skin pH Matters More Than We Thought
Unfortunately, eczema is becoming increasingly common. While people with healthy skin including a healthy skin pH can have normal contact with water during a shower and can swim without any problems, this is often a painful experience for those with eczema. This is not only because the skin is already too dry and damaged, but also because water can further disrupt the skin barrier by directly affecting the skin's pH. I'll explain how this works in this blog post.
The average skin pH (acidity)
For decades, skin professionals have been taught that the physiological pH of the skin is around 5.5. This number has become almost dogma in dermatology and cosmetic science. However, modern research paints a more nuanced picture: the average pH of healthy human skin is considerably lower, typically around 4.7, with reported ranges between 4.2 and 5.8.
This distinction may seem minor, but it has profound implications for skin barrier function, enzymatic activity, and the cutaneous microbiome.
The importance of an acidic skin surface
The slightly acidic nature of the skin surface—often referred to as the acid mantle—is essential for numerous biological processes within the epidermis.
Among the most important is the regulation of epidermal enzymes involved in keratinocyte differentiation. Newly formed keratinocytes originate in the stratum basale, after which they gradually migrate upwards through the epidermis while undergoing a complex process of maturation. Ultimately they become corneocytes, the flattened dead cells that form the stratum corneum, the outermost barrier of the skin.
A stable acidic pH is required for the optimal functioning of enzymes responsible for:
lipid processing in the epidermis,
proper formation of the skin barrier,
controlled desquamation of corneocytes.
When the pH of the skin surface deviates for prolonged periods—either becoming too alkaline or excessively acidic—these enzymatic processes can become disrupted. The consequences may include impaired barrier formation, increased transepidermal water loss, scaling, and greater permeability to external irritants.
Skin pH and the microbiome
The skin’s acidity also plays a central role in regulating the cutaneous microbiome. Beneficial commensal microorganisms such as Staphylococcus epidermidis thrive in a slightly acidic environment. These microbes contribute to skin health in several ways:
they inhibit colonization by pathogenic microbes,
they produce antimicrobial peptides,
they contribute to maintaining the acidic skin environment.
This creates a mutually beneficial relationship: the acidic pH supports commensal microbes, and those microbes in turn help maintain the acidic environment and strengthen the skin’s immune defense.
However, when skin pH rises, this balance can shift. Certain opportunistic microbes, including Staphylococcus aureus and fungi like Candida albicans and Malassezia , are less sensitive to increases in pH and may even proliferate more easily under such conditions. This microbial imbalance is frequently observed in inflammatory skin diseases such as atopic dermatitis, where elevated skin pH has been consistently reported. The increased presence of S. aureus in these patients illustrates how changes in pH can directly influence microbial ecology and disease susceptibility. To combat such pathogens, not only short-term medication is needed but also improvement of skin pH for long-term effects.
Water exposure: an underestimated factor
One of the most underestimated influences on skin pH is simple contact with water.
Activities such as washing, showering, bathing, swimming all temporarily increase skin surface pH. After water exposure, the pH of the skin may remain elevated for several hours!
Healthy skin possesses a natural mechanism to restore its acidity: the buffering capacity of the skin barrier. Through lipid metabolism, sweat components, and microbial activity, the skin can gradually re-acidify itself.
However, in individuals with compromised skin barriers or inflammatory skin diseases, this recovery process can be significantly slower or incomplete. As a result, the skin may remain in a more alkaline state for prolonged periods, increasing vulnerability to irritation, barrier disruption, and microbial imbalance.
When skincare interferes with the buffer system
Interestingly, not only water but also aggressive skincare practices can interfere with the skin’s buffering capacity. For example, frequent use of strong chemical exfoliants such as fruit acids (alpha-hydroxy acids)—often formulated at pH values well below 4—can temporarily improve skin texture and brightness. Many skin professionals recognize the initial positive effects: smoother skin and improved radiance.
However, with frequent or prolonged use, some individuals develop: redness, irritation, dryness and increased sensitivity. One possible explanation is long-term disturbance of the skin’s pH balance and buffering mechanisms, particularly when strong acids are used repeatedly without adequate recovery periods. In such cases, discontinuation of these treatments is often necessary to allow the skin barrier to recover—a process that may take time.
The role of daily hygiene
Modern hygiene habits can also play a role in altering skin pH. Many people—especially younger individuals—enjoy long, hot showers, often combined with cleansers or soaps. Unfortunately, many traditional soaps have alkaline pH values, sometimes well above pH 9. When alkaline soaps are combined with prolonged water exposure (water itself typically has a pH around 7–8), the skin barrier may be repeatedly challenged.
For individuals with sensitive or compromised skin like eczema or acne, this combination can be particularly problematic.
Practical recommendations may therefore include:
limiting the duration of showers,
avoiding excessively hot water,
minimizing the use of alkaline soaps,
using water-only cleansing in sensitive areas when appropriate.
In some cases, less frequent washing (so not daily, but every few days) may actually support better barrier recovery.
Skin pH within the skin–gut axis
While skin pH is often discussed purely as a dermatological parameter, it may also be viewed through the broader framework of the skin–gut axis. Both the gut and the skin host complex microbial ecosystems that interact with the immune system and barrier function. Disturbances in microbial balance—whether in the gut or on the skin—can influence inflammatory processes and barrier integrity.
From this perspective, maintaining a stable acidic skin environment is not only important for local skin health but may also contribute to the broader ecological balance that underlies the skin–gut connection.
Understanding how everyday factors such as water exposure, cleansing habits, and cosmetic treatments influence skin pH may therefore be an important piece of the puzzle in maintaining long-term skin health.
P.S.... in my skin-gut axis books, I extensively discuss skin pH and the influence of sebum, nutrition, diet, the skin microbiome, lifestyle, and skincare in a separate chapter. My books
Marcelline Goyen BSc skin therapy
Scientific references
Schmid-Wendtner M-H & Korting H. (2007) pH and Skin Care. ABW Wissenschaftsverlag GmbH ISBN 978-3-936072-64-8
Goyen Marcelline (2019). The skin-gut connection. www.skin-gut-axis.com/ourbooks
Goyen Marcelline (2023 / 2024 / 2025). The amazing world of the skin-gut axis, including the role of the microbiome www.skin-gut-axis.com/ourbooks
Lambers H. et al. (2006). Natural skin surface pH is on average below 5, which is beneficial for its resident flora. International Journal of Cosmetic Science.https://doi.org/10.1111/j.1467-2494.2006.00344.x
Proksch E. (2018). pH in nature, humans and skin. Journal of Dermatology.https://doi.org/10.1111/1346-8138.14337
Fluhr J.W., Elias P.M. (2002). Stratum corneum pH: formation and function of the acid mantle. Exogenous Dermatology.
Ali S.M., Yosipovitch G. (2013). Skin pH: from basic science to basic skin care. Acta Dermato-Venereologica.https://doi.org/10.2340/00015555-1531
Cork M.J. et al. (2009). Epidermal barrier dysfunction in atopic dermatitis. Journal of Investigative Dermatology.https://doi.org/10.1038/jid.2009.133
Sanford J.A., Gallo R.L. (2013). Functions of the skin microbiota in health and disease. Seminars in Immunology.https://doi.org/10.1016/j.smim.2013.09.005
Korting H.C., Hübner K. (1990). Influence of repeated washings with soap and synthetic detergents on skin pH and resident flora. International Journal of Cosmetic Science.
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