pH of Skin

pH of skin

Inside cells, there is liquid substance, and the pH of this liquid is kept constant and is influenced by external / environmental factors. The pH of our skin is nothing but the pH of an ultra-thin moist film barrier on top of our skin, a mixture of sweat and sebum. This is commonly known as the “acid mantle” – and it has a pH between 4 and 5.5, which means it is very mildly acidic. In this moist environment, some ‘beneficial’ bacteria feel at home. These beneficial bacteria help to stabilize the pH of the skin, since they produce small amounts of lactic acid. This ‘good’ bacteria increases the skin’s production of ceramides, which promotes a healthy skin barrier. The pH of the skin can change slightly depending on the amount and quality of our sweat.

Like every other organ in our body, skin performs its best within a narrow, ideal environment, especially when it comes to pH. When it deviates from that magic number, harmful bacteria could grow, triggering inflammation and other unwilling skin conditions. Our skin and its pH level do get affected short-term by using certain cosmetic products – especially soaps and bath foams. The pH of all toilet soap bars and almost all the bathing bars sold in the market are alkaline in nature with pH between 9 and 10 [Evaluation of pH of Bathing Soaps and Shampoos for Skin and Hair Care, Indian Journal of Dermatology, 2014, Sept-Oct, 59(5), 442-444].

Our skin and its pH level do get affected short-term by using certain cosmetic products – especially soaps and bath foams. Thus, the soaps and the other body cleansers which are made of highly alkaline substances work to eradicate our fatty sebum layer and natural flora (good & beneficial bacteria) on skin. Removing this fatty layer can make us “feel good” because it gives us the impression that we are clean. But in fact, the alkaline soaps and body testosteron undecanoate cleansers remove a very important part of our natural protection against disease and neutralise the thin protective layer called “acid mantle”. This can be noticed by a small rise in the pH of our skin to above 6.

If the skin feels tight squeaky clean after washing, it is the truest sign of having used the cleanser with a high pH and the consequent damaged skin barrier. Probably the washing strips away the acid mantle which increases the chances of skin damage such as redness, inflammation, scaling, dryness, infection, and sensitivities such as irritation and itching. Higher (alkaline) pH products dilate follicles (swelling them), which increases the permeability of skin making it more vulnerable to microorganisms and irritants and also increased water loss from skin.

Soaps and Body washes can really vary in pH and commercial soaps have a pH range of 9-11, which can dry out skin and make it more susceptible to bacterial growth. The pH between 6 and 6.5 is conducive for bacteria associated with acne. Studies have shown that a higher or more alkaline pH is seen more often in people with acne. The long-term use of the alkaline products can prevent the skin from maintaining its optimal pH levels. One needs to find a cleanser in the pH range as close to the skin as possible to maintain healthy skin. A good cleanser cleans the skin without stripping it of oils or damaging the acid mantle.

Acid Mantle

Ninety years ago – in 1928, the term “acid mantle” was coined by the physicians Heinrich Schade and Alfred Marchionini in Kiel, Germany. This acid mantle is characterised by having a pH of 5.5, which is the physiological condition of healthy skin, from the time we are small and throughout our entire lives.

The acid mantle is a very fine and very vital film on the surface of our outermost skin layer (stratum corneum) – on the top of the outer layer of skin called epidermis. It is slightly acidic (ranging from 4.4 – 6 pH) and this helps maintain skin-barrier function and the body’s ability to ward off infection. The acid mantle is made up of sebum secreted from sebaceous glands, sweat from skin pores, flat dead skin cells knitted together, lactic acid, urocanic acid, fatty acids, and pyrrolidine carboxylic acid. It is designed to keep bad things out and good things in. This protective barrier also contains other acids and proteins with antimicrobial properties, and acts as a shield against bacteria, fungi and viruses that could penetrate the skin.

The acid mantle is body’s first layer of defence against bacteria, viruses and harmful foreign bodies. It also prevents cellular water loss and seals moisture in and thus keeps skin soft, elastic, smooth and supple. It helps to keep moisture and nutrients ‘in’ while keeping allergens and toxins ‘out’. The acid character and its gradual change within the skin also help to orchestrate epidermal differentiation and corneocyte shedding. For many more biochemical processes within the skin, the compartmental pH is crucial, for example, in pigmentation, ion homeostasis, epidermal (stem) cell behavior, and so on. It is therefore also no surprise that pH shifts in skin have been observed in various skin pathologies. More recently, in carefully controlled trials (acne, atopic dermatitis, incontinence-associated dermatitis, aged skin), the benefits of targeted skin acidification have become evident and the use of topical preparations with reduced pH is recommended.

This delicate layer can be easily and very commonly damaged, scrubbed and stripped by over-cleansing, regular use of acids/peels, extreme heat & cold, sun, air conditioning, pollution, free-radicals, some skincare ingredients e.g. SLS (sodium lauryl sulfate) leaving the skin open to infection and bacteria which damage health of skin and also its visual complexion. Also, with the age, the acid mantle diminishes and skin becomes less acidic, making it drier and more prone to fine lines and wrinkles.

Once damaged, the acid mantle can take anywhere from 15 minutes to 14 hours to restore itself, depending on how much it has been disrupted or damaged. One needs to choose a good personal care product that is less likely to disrupt the skin’s acid mantle and leave your skin looking and feeling softer compared to after using alkaline pH soaps and body washes. One needs to look for skin-care products with a pH of 5.5. If anything, the pH of skin care products could be as low as 4.5 and as high as 7. The general rule is that “slightly acidic is preferred. Using pH neutral or even better the cleanser at skin pH that doesn’t contain any alcohol or strong detergents would protect the acid mantle. Surber C, Humbert P, Abels C, Maibach H. Curr Probl Dermatol. 2018;54:1-10. doi: 10.1159/000489512. Epub 2018 Aug 20