Reasons the pH of Your Skin Matters
Our skin has a naturally acidic pH between 4-6 and functions at its best somewhere in this range. When outside of this range, your skin’s acid mantle is disrupted and you can experience issues like dryness, flakes, acne, and more. This is why the pH of skin and skincare products matter for healthy skin.
What is pH?
If you’ve ever taken a chemistry class you probably have a vague awareness of what pH is. It stands for “power of hydrogen” and is a measurement of the activity of hydrogen in a solution. The pH scale ranges from 0-14 with 7 as neutral. Anything below a pH of 7 is considered acidic and anything above a pH of 7 is considered alkaline.
The difference between each whole number on the pH scale is actually tenfold. This means that if you’re using a cleanser with a pH of 7, it’s 10 times more alkaline than a cleanser with a pH of 6 and 100 times more alkaline than a cleanser with a pH of 5. This is why paying attention to the pH of your products is important because only a few units different in pH can make a huge difference to your skin. You might have noticed that there are only wet substances on the scale above and this is because only wet substances have a pH. The pH measurement of our skin actually comes from the moisture in our acid mantle!
What’s the acid mantle?
The acid mantle is a thin protective film on our stratum corneum (the outermost layer of our skin) that's composed of skin oils, sweat, natural moisturizing factors (NMFs), lipids, lactic acid, and a few other things. Our acid mantle is slightly acidic at a pH of around 5 and protects our skin from bacteria, moisture loss, and environmental damages. A healthy acid mantle also regulates our sebum production, allows dead skin cells to turnover properly, and keeps our healthy bacteria growth in check. It’s been proven that skin with a pH of 5 is healthier, stronger and more hydrated than skin above 5. Bacteria and pollutants are usually alkaline so keeping our acid mantle in a healthy acidic state helps it fight off these harmful elements and keeps them from penetrating into our skin and causing damage.
What disrupts the acid mantle?
Many things play a role in disrupting the acid mantle but the biggest mistake I see people making is using alkaline cleansers. Alkaline cleaners are the ones that leave your face tight and dry after use - they’re typically very foamy and some even have pHs as high as baking soda at a 9! Using these, even if only on your skin for a few seconds, will raise the pH of your acid mantle.
Over-exfoliation is also a major contributor to acid mantle disruption which is why it’s important to be cautious when using active ingredients and not overdoing it. Environmental factors like pollution and UV rays can also throw your acid mantle out of wack so a daily SPF is always a must.
It’s important to know that just because something has a low pH does not mean it’s a good idea to put it on your skin. Take lemon juice for example - a quick google for lemon juice in skincare will show lemon juice DIY toners, blackhead treatments, and skin brightening concoctions due to it’s AHA properties. However, please never put lemon juice on your face (@bellathorne). It has a pH of 2, is highly irritating, makes you significantly more sensitive to the sun and can even cause chemical burns. Since every lemon is different, it’s impossible to control how much citric acid you’re getting into.
What happens when the acid mantle is disrupted?
Since the acid mantle protects and maintains the structure of our stratum corneum, disrupting it causes issues like dry skin, flakiness, dehydrated skin, sensitivity, oily skin, acne, and more. How could this cause dry AND oily skin, you might ask? Well, when your acid mantle is disrupted, your stratum corneum (AKA moisture barrier) that it protects becomes compromised and we experience TEWL (transepidermal water loss). Now that your skin is dry and lacking water, it will try to repair itself by over-producing oils. A healthy acid mantle also regulates the turnover of dead skin cells in the stratum corneum so when that’s not working properly, dead skin cells build up which causes the appearance of flaky skin. The combination of these issues results in dehydrated skin - skin that's dry and oily. A disrupted acid mantle is less likely to effectively fight off acne-causing bacteria so that means breakouts. Wasn’t that what the alkaline cleansers that disrupted it were supposed to fight in the first place? Hmm, interesting.
How to keep the skin’s Ph low and healthy
Keeping skin’s pH levels low and healthy is critical for maintaining barrier integrity. Here are a few ways to do so:
Use a low pH cleanser. A cleanser with a pH around 5.5 will work great to cleanse your skin while keeping it balanced and ready to protect you from the outside world. I know it’s tempting to reach for those creamy, foamy cleansers but trust me, they’re doing more harm than that luxurious feeling is worth. I’d recommend you to toss out any cleansers with a pH higher than 6.5 unless it was prescribed by your dermatologist.
Use a pH balancing acid toner. These use low levels of acids to force down the pH of your skin to a healthy level. It’s an optional step and isn’t necessary if you’re already using a low pH cleanser or other acids.
Be cautious when using exfoliants (both physical and chemical) and make sure not to over-exfoliate.
Wear sunscreen!
How to know the ph of products
If you want to know the pH of a skincare product, it’s likely that someone has already tested it and posted it online so you can find it with a quick Google search. However, if you want to test the pH of products on your own, you can buy pH testing strips online for around $5-$10.
If pH in skincare products is interesting to you, check out my post on how to layer skincare products by ph level!