What Does pH Balanced Mean? (What Is Skin pH?)

Life is all about balance and skincare is no exception. Poor skin hygiene can lead to skin conditions and infections but over-cleansing the skin can cause damage and irritation. One key balancing act regarding skincare is maintaining the skin’s natural pH level. But what is skin pH? And what does pH balanced mean exactly?

Here is everything you need to know about the skin’s pH and how to balance it.

What Is Skin pH?

The surface of the skin has a naturally acidic pH called the ‘acid mantle’ which enables the skin to control resident bacteria and maintain normal skin function ^[1]. The acid mantle is made up of sebum, sweat, lactic acid, fatty acids and forms a film-like cover over the skin ^[2].

The term ‘pH’ is an acronym for ‘potential hydrogen’ ^[2] and refers to the concentration of hydrogen ions in a given substance. It is a base-ten logarithm which means that it is based on tens and each decrease in pH by one is a ten-fold increase in acidity ^[3].

The pH scale ranges from 0-14 where 0 is the maximum acidic value, 14 is the maximum alkaline value, and 7 is neutral.

Initial research suggested that normal skin surface pH values vary between 4.0 and 7.0 with the majority of values between 4.2 and 5.6 ^[4]. Values have been found to vary depending on the experimental method used. However, the general consensus from the majority of research suggests a skin pH value of 5.4-5.9 ^[3].

Thus, a pH of 5.4-5.9 is considered to be ‘skin neutral’ and is often seen on cosmetic product labels ^[1]. However, some research has found that untreated skin can have a pH as low as 4.7 ^[1]. Either way, it is safe to say that, in its natural state, the skin is slightly acidic.

What Does pH Balanced Mean?

In terms of skin, pH balanced means that the natural pH level of the skin (5.4-5.9) is maintained. In terms of skincare products, pH balanced means that the pH of the product is close to the skins natural pH (usually, a pH of 5.5 is considered pretty good) and, thus, should not dramatically alter the pH level of the skin.

Why Is pH Balance Important For Skin?

The skin’s natural protective barrier, the stratum corneum, contains a number of enzymes that are pH-dependent – meaning that they require a certain pH level to function properly. For example, an enzyme that is essential for the production of ceramides, b-Glucocerebrosidase, requires an optimum pH of 5.6 ^[3].

In fact, the activity of b-Glucocerebrosidase is ten-times lower at a pH of 7.4 than at a pH of 5.5 ^[5]. As a reduction of ceramides in the stratum corneum directly affects the barrier properties and hydration of the skin ^[6], an acidic pH is required for normal skin barrier function and repair.

A more acidic skin pH also allows for normal flora or ‘good bacteria’ growth, while pathogenic or ‘bad’ bacteria thrive at neutral pH levels ^[7].

This means that pH balance is important for skin health by maintaining barrier function and skin hydration and by keeping harmful bacteria under control.

Factors That Affect Skin pH

There are a number of internal and external factors that can affect the pH level of the skin, including; age, skin site, genetics, ethnicity, sebum, skin moisture, sweat, detergents/cosmetics/soaps, occlusive dressings, skin irritants, and topical antibacterials ^[7].

For example:

• Newborn babies and the elderly have a higher skin surface pH (more alkaline)
• The pH of the skin under the arms and around the groin is higher (more alkaline) which can allow odor-producing bacteria to thrive.
• Darker skin appears to have a lower pH (more acidic) than lighter skin ^[3][7].
• Women have a higher skin surface pH than men, with men having a skin surface pH of below 5 and women of above 5 ^[8].
• Excessive sweating due to heavy exercise or a hot environment can increase skin pH ^[9].
• Skin pH rises for at least a few hours after using soaps which are alkaline and usually have a pH of 10.5-11.0.
• Cleansers with detergent-based surfactants (known as syndets) usually have a pH of less than 7 and are often formulated at the same pH as skin. However, they also lead to a rise in skin surface pH, albeit to a lesser extent and for a shorter duration of time than soap-based cleansers.
• Cleansing with water, alone, can also increase skin pH in a similar way to syndets ^[3][7].

What Happens When Skin pH Is Unbalanced?

We’ve already mentioned that a balanced skin pH is required for normal skin barrier function, adequate skin hydration, and to control and balance good vs bad bacteria. If skin pH is unbalanced, then the skin may be susceptible to dehydration and infection.

Due to this, several inflammatory and infectious skin conditions have been linked to an unbalanced skin pH. For example, individuals with skin conditions such as atopic dermatitis, contact dermatitis, radiodermatitis, seborrheic dermatitis, ichthyosis vulgaris, eczema, and acne seem to have a higher skin pH than normal (alkaline skin) ^[10][11].

One study found that individuals with acne had a higher skin pH than those without acne (6.35 vs 5.09) ^[2]. This may be partially due to the effect of skin pH on p-acnes bacteria growth. The p-acnes bacteria contribute to the formation of acne as it feeds off of sebum and rapidly multiplies when there is an overproduction.

As bacteria thrive when the skin’s pH is neutral, an increase in skin pH provides a more p-acnes friendly environment. Topical antibiotics (e.g. oxytetracycline, erythromycin) and hydroxy acids (e.g. salicylic acid, glycolic acid) that are often used to treat acne can help decrease skin surface pH. It is often thought that this is one of the ways in which they improve the appearance of acne ^[12].

Summary: What Does pH Balanced Mean?

The skin’s natural pH is slightly acidic which allows for optimal barrier function and protects the skin from infection. When skin is pH balanced, it means that it has a normal, acidic pH. In terms of skincare, pH balanced refers to how close the pH of the product is to the skin’s natural pH (a pH of 5.5 is often considered pH balanced).

When the skin’s pH is more alkaline, skin hydration may be reduced and bacteria may thrive. For this reason, alkaline skin is considered ‘unbalanced’ and may be associated with inflammatory skin conditions.

The use of soap-based cleansers can increase skin pH for a few hours leading to skin barrier damage. These days, a lot of cleansers are pH balanced and are usually referred to as ‘syndets’ (synthetic detergents) and increase skin pH to a lesser extent and for a shorter duration than soap-based cleansers. In fact, they alter pH in a similar way that water does.

Preventing increases in skin pH by using pH balanced cleansers and acidic treatments can help a number of inflammatory skin conditions, including acne.

References

1. Lambers, H., Piessens, S., Bloem, A., Pronk, H. & Finkel, P. (2006). ‘Natural skin surface pH is on average below 5 which is beneficial for its resident flora’, Int J Cosmet Sci., 28(5), 359-370. Available at: https://www.ncbi.nlm.nih.gov/pubmed/18489300
2. Prakash, C., Bhargava, P., Tiwari, S., Majumdar, B. & Bhargava, R. (2017). ‘Skin surface ph in acne vulgaris: insights from an observational study and review of the literature’, J Clin Aesthet Dermatol., 10(7), 33-39. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5605222/
3. Schmid-Wendtner, M. & Korting, H. (2006). ‘The pH of the skin surface and its impact on the barrier function’, Skin Pharmacol Physiol., 19, 296-302. Available at: https://epub.ub.uni-muenchen.de/16348/1/10_1159_000094670.pdf
4. Blank, I. (1939). ‘Measurement of pH of the skin surface: II. pH of the exposed surfaces of adults with no apparent skin lesions’, J Invest Dermatol., 2(2), 75-79. Available at: https://www.sciencedirect.com/science/article/pii/S0022202X15498483#tlnote1
5. Mauro, T., Holleran, W., Grayson, S., Gao, W., Kriehuber, E., Behne, M., Feingold, K. & Elias, P. (1998). ‘Barrier recovery is impeded at neutral pH, independent of ionic effects: implications for extracellular lipid processing’, Arch Dermatol Res., 290(4), 215-222. Available at: https://www.ncbi.nlm.nih.gov/pubmed/9617442
6. Tfayli, A., Jamal, D., Vyumvuhore, R., Manfait, M. & Baillet-Guffroy, A. (2013). ‘Hydration effects on the barrier function of stratum corneum lipids: Raman analysis of ceramides 2, III and 5’, Analyst, 138(21), 6582-6588. Available at: https://www.ncbi.nlm.nih.gov/pubmed/23951566
7. Ali, S. & Yosipovitch, G. (2013). ‘Skin pH: From basic science to basic skincare’, Acta Derm Venereol, 93, 261-267. Available at: https://www.medicaljournals.se/acta/content_files/files/pdf/93/3/3854.pdf
8. Luebberding, S., Krueger, N. & Kerscher, M. (2013). ‘Skin physiology in men and women: in vivo evaluation of 300 people including TEWL, SC hydration, sebum content, and skin surface pH’, Int J Cosmet Sci., 35(5), 477-483. Available at: https://www.ncbi.nlm.nih.gov/pubmed/23713991/
9. Herrmann, F. & Mandol, L. (1955). ‘Studies of pH of sweat produced by different forms of stimulation’, J Invest Dermatol., 24(3), 225-246. Available at: https://www.jidonline.org/article/S0022-202X(15)48679-8/pdf
10. Chikakane, K. & Takahashi, H. (1995). ‘Measurement of skin pH and its significance in cutaneous diseases’, Clin Dermatol., 13(4), 299-306. Available at: https://www.sciencedirect.com/sdfe/pdf/download/eid/1-s2.0-0738081X9500076R/first-page-pdf
11. Proksch, E. (2018). ‘pH in nature, humans, and skin’, J Dermatol., 45(9), 1044-1052. Available at: https://www.ncbi.nlm.nih.gov/pubmed/29863755
12. Korting, H., Kerscher, M., Schafer-Korting, M. & Berchtenbreiter, U. (1993). ‘Influence of topical erythromycin preparations for acne vulgaris on skin surface pH’, Clin Investig., 71(8), 644-648. Available at: https://www.ncbi.nlm.nih.gov/pubmed/8219662/