For most of us, the pH scale is a vague memory from school chemistry lessons.

That same pH scale gets a lot more interesting when you realise it may be having an impact on your complexion. It may even be contributing to that skin condition you just can’t shift.

To understand what pH is, why it matters, and how you can cultivate the optimum skin pH level, keep reading.

Contents

What is pH?
What’s a normal skin pH level?
Do you really want acidic skin?
What disrupts normal skin?
How to balance skin pH naturally
How do you know if your skin pH is too high?
Takeaway points

What is pH?

pH stands for ‘potential for hydrogen’ or ‘power of hydrogen’ (believe it or not, the scientists can’t agree). It’s a scale that measures how acidic or how alkaline something is.

This scale runs from 0 to 14. Seven is neutral, while anything under 7 is acidic and anything over 7 is alkaline. You come across different pH values in your everyday life:

An easy way to remember this is that acidic substances tend to be sour, while alkaline substances tend to be bitter (but please do not taste battery acid to test that theory!)

You have a pH too. Or, to be more specific, different areas of your body have different pH values:

[1, 2]

As you can see, a healthy skin surface has a slightly acidic pH.

What’s a normal skin pH level?

The uppermost layer of healthy skin—known as the stratum corneum—has a pH between 4.1–5.8 [3, 4]. This value increases (becomes more neutral) as you go into the deeper layers of your skin, but it means that the part of your skin you see and touch is slightly acidic.

That’s right. Forget the popular notion of ‘alkalising your body’, as an acidic skin surface is a natural and desirable state.

This acidic layer was discovered way back in the 19^th century, and was dubbed ‘the acid mantle’ in 1928 [5]. Even today, scientists aren’t 100% sure what creates and maintains this acid layer, but they do know it’s partly formed by fatty acids from your skin oil, plus special compounds in your sweat [6].

Note that the pH of a healthy skin surface has a slightly acidic pH. Skin can become more neutral or alkaline for a variety of reasons, and this often leads to problems (more on this later).

Lots of factors influence your skin pH, such as:

Age. Babies are born with a very slightly alkaline skin pH—7.08 to be precise [7]—but this becomes acidic in the first few days of life. Most people maintain an acidic skin surface during their adult life, but it gradually gets more alkaline the older you get [8].

Gender. Men tend to have naturally more acidic skin than women [9].

Body area. Different skin areas have different pH values. Your forehead and upper eyelid tend to be the most acidic, while the skin found in your underarms, groin and between your toes can be more neutral [1]. This differentiation is likely because the skin on your face is more exposed to the elements, so needs to have a stronger barrier function.

Ethnicity. The more pigmented the skin, the lower its pH [10].

You can’t do anything about the above factors, but others are more under your control. These include:

Sebum. Interestingly, the oilier your skin, the lower its pH appears to be [11]. This doesn’t mean that more oil is always better—just that some natural oil is preferable to having dry skin.

Sweat. In the same vein, some sweat is good, but too much can lessen the acidity of your skin surface, at least temporarily [12].

Cosmetic products. More than anything else, these have the power to damage your skin’s acidity [5].

We’ll talk about what you can do to optimise your skin pH in the ‘How to support a healthy skin pH’ section.

What disrupts normal skin pH?

The main way you disrupt your skin’s acid mantle is through using too many alkaline products. This means anything that’s soap-based.

Scientists have found that washing your hands with soap causes the pH on your palms to increase by an average of three units [19]. So, say your hands had a happy skin pH of 4.5, one little rinse could make them shoot up to 7.5. When you consider that a change of just 0.5 pH units starts to affect your skin’s function, this is no laughing matter [20].

This effect is directly proportional to the degree of alkalinity of the product. In other words, the more alkaline a product is, the more it will change your skin’s pH [21]. Bear in mind that plain old soap-and-water has a pH of 12, and many products on the market have a pH value of at least 8.

It’s not all bad news, though. Healthy skin does have an in-built buffer system to restore its natural pH [22]. That’s why you can (and should) continue to wash your hands when you need to.

But have you ever noticed that after a prolonged period of repeated washing, your skin starts to feel dry, tight and even rough? That’s because your buffer system is struggling, and it can start to take hours for it to restore a happy pH—if it does at all [14].

Research suggests that too much washing with alkaline products (or applying leave-on alkaline products) can induce a long-term shift in pH, ultimately making your skin more alkaline too [21]. As you learnt above, that can contribute to all sorts of skin problems.

Don’t stop washing your hands. But do consider what you’re putting on your face and body.

To learn how to create an effective skincare routine using as few products as possible, check out The Happy Skin Roadmap.

How to balance skin pH naturally

The easiest way to optimise your skin pH’s is to use products that have a slightly acidic pH. This is because if their pH is close to that of your natural skin, they won’t disrupt your acid mantle.

The challenge is that not all products list their pH. But there are a few things you can look out for:

– How does your skin feel after using a product? If your skin becomes tight or uncomfortable, the likelihood is that the product is too alkaline.

– Does the product contain SLS? This stands for sodium lauryl sulfate, and it’s a known acid mantle stripper.

– Does the product say pH balanced? If so, that means it has a pH of 4–5.5, which will keep your acid mantle happy.

You can also buy some litmus strips and test the pH of the product yourself, but this will only work if it contains water (often listed as ‘aqua’ on ingredients labels). If all else fails, get in touch with the brand or manufacturer and ask them about the pH of their product. They should know because they have to test it.

Every month, more research is coming out on the importance of pH, which means more and more brands are optimising their formulations. Here are a few that are worth checking out for pH-balanced products (and I have no conflict of interest here!):

Green People

Gallinée

Drunk Elephant

Paula’s Choice

The Ordinary

Research on how we can influence the acid mantle from the inside-out is much more limited, but it’s worth trying a couple of approaches:

a) Be mindful of sweat

b) Manage your sebum

Let’s look at each in more detail:

a) Be mindful of sweat

As you learnt above, some components of sweat help to form the acid mantle, but too much sweat can weaken it.

This weakening occurs in the areas that get most sweaty—e.g. your underarms—and it usually self-resolves after about an hour [23]. Still, it’s worth bearing in mind if you suffer from a skin condition such as eczema that’s exacerbated by a too-high pH.

Get in the habit of washing (with a pH balanced product, of course) as soon as you can after exercise or heavy sweating.

b) Manage your sebum

The relationship between the acid mantle and skin bacteria goes both ways, and it’s regulated by your natural skin oil (sebum). Some sebum is critical for a healthy acid mantle. But too much sebum can affect the balance of bacteria on the skin, which could in turn negatively affect the acid mantle [24].

The bottom line? You want just the right amount of sebum.

You can optimise your sebum levels by eating a blood sugar-balancing diet, and by focusing on eating foods rich in vitamin A. This essential nutrient has many functions in your body, one of which is regulating sebum production [25].

The richest sources of vitamin A are liver and cod liver oil. If you don’t fancy eating these (or if you’re pregnant, in which case you shouldn’t eat them), you can up your intake of orange-coloured vegetables such as sweet potatoes, carrots and squash, along with dark leafy greens such as kale. These contain a special compound called beta-carotene that’s converted into vitamin A in your body.

As more research emerges on exactly how the body forms the acid mantle, we’ll know how we can optimise it through our diet and lifestyle.

Takeaway points

The pH scale plays a role in your everyday life, and it should influence how you take care of your skin. Here’s what you need to remember:

– Different parts of your body have different pH values. The uppermost layer of your skin is acidic, which is why it’s known as the ‘acid mantle’.

– Your acid mantle plays a crucial role in maintaining the integrity of your skin. Skin that is less acidic (or more alkaline) is associated with conditions such as eczema, psoriasis and acne.

– You can damage your acid mantle by using too many alkaline (soap-based) products.

– If a product makes your skin feel tight or uncomfortable after use, it’s usually a sign that it’s too alkaline. To help maintain your acid mantle, look out for products that are ‘pH balanced’ instead.

– To further support your acid mantle from the inside-out, shower soon after excessive sweating. You should also eat a blood-sugar balancing diet with foods rich in vitamin A, as this helps to regulate your sebum production—which is also important for a happy skin pH.

Want a foolproof guide to great skin? Get your copy of The Happy Skin Roadmap.