The Ultimate Guide to pH and Your Skin
Few skin care topics have become as mired in confusion and worry as pH. How can two little letters have such an impact on our skin? As it turns out, how pH relates to our skin and the products we use is fascinating. And don’t worry, finding pH-balanced skin care is easier than you might think. We’ll put your mind at ease about mixing skin care products with different pH levels so you can get through your routine faster.
What is pH?
The term “pH” refers to the “potential of hydrogen”. It concerns the activity of hydrogen ions (ions are molecules that carry a positive or negative charge) in a water-based solution. Hydrogen makes up two-thirds of water, water being two hydrogen molecules plus an oxygen molecule, H²o.
The pH of a solution is indicated by a numeric scale that runs from 0-14. Anything below 7 (which is pH neutral) is considered acidic, while anything with a pH greater than 7 is considered alkaline. Lemon juice has a pH of 2 — very acidic, while ammonia has a pH of 12, which is highly alkaline.
It’s important to know that while the differences between pH numbers might seem small, the pH scale is logarithmic, not linear. That means the difference between each pH number is multiplied by 10, which is why a pH of 3 is 100 times more powerful than a pH of 5.
What is the ‘Normal’ pH of Skin?
It might surprise you to find out that the skin’s surface and uppermost layers are naturally acidic, making it compatible with acidic skincare products. Although research on the skin’s pH range cites various numbers, the collective research shows skin’s average pH is 4.7.
Men’s skin tends to be more acidic than women’s skin, and although the pH of our skin increases with age, it remains acidic. When we’re born, our skin has a neutral pH that becomes acidic within a couple of weeks after birth.
What is the Skin's Acid Mantle?
Skin has a protective film on its surface that’s known as its acid mantle. The acid mantle plays a vital role by working with skin-natural ingredients like ceramides, cholesterol, enzymes, sweat, and even our skin’s own oil to protect the skin’s surface and lower layers from external threats.
Skin’s acidic pH also plays a role in keeping its delicate microbiome balanced. An acidic microbiome makes it more difficult for harmful pathogens to multiply but this allows the good stuff to flourish.
How does pH Affect the Skin?
Repeatedly disturbing the skin’s pH to a strong degree can lead to or worsen many problems, including common skin disorders. That dry and tight feeling from washing with a bar or liquid soap? That’s caused by alkaline.
In order to avoid problems, many people look for pH-balanced skin care products, but not all products are labelled with their pH levels. What should you do then? We have encouraging news: The vast majority of rinse-off and leave-on skin care products are already pH-balanced. Cosmetic chemists are aware of how the pH of skin care products impacts our skin, so they usually ensure their formulas strike the right balance.
If you’re wondering what’s meant by “pH-balanced”, it refers to products formulated with a pH that falls in the range of normal, healthy skin. That range is most often cited as being between pH 4 and pH 7. Although it’s true that some skin care products have pH numbers outside this range, in most cases this isn’t cause for concern.
Research has shown that mild disruptions in skin’s pH (such as from using an AHA or BHA leave-on exfoliant whose pH is 3.6 or a mineral sunscreen with a pH of 7.5) are temporary. The skin naturally equalises to its normal pH, typically within an hour. And there’s actually a benefit: Research has shown that acidic products stimulate skin to produce key substances it needs to look smooth, supple, and hydrated.
On the other hand, using highly acidic (pH 2.5 or lower) or alkaline (pH 8 or greater) products causes a more significant disruption in the skin’s pH, so it takes longer for the skin to get back to normal.
During the time it takes for skin to return to normal, it is vulnerable to factors that can trigger breakouts, signs of eczema, redness and sensitivity. That’s why daily use of products whose pH is too high or too low visibly and progressively damages skin.
The pH of Skin Care Products
We mentioned above that most skin care products are pH balanced, and this applies to products from Paula’s Choice, too. Here are common pH ranges for the major categories of our skin care products:
- Cleansers: pH 4.5–7
- Toners: pH 5–7
- Sunscreens: pH 5–7.5
- AHA and BHA exfoliants: pH 3.2–3.9, with any reading between 3 and 4 considered most effective
- Moisturizers: pH 5–7
- Serums: pH 4–6
- Vitamin C (ascorbic acid) products: pH 2.6–3.2
- Retinol products: pH 4–6.6
Can you Layer Skin Care Products with Different pH Levels?
We’re often asked if it’s ok to immediately layer products with differing pH levels, such as applying a moisturizer over an AHA exfoliant. People worry that doing so causes one or both products not to work because the different pH levels conflict with each other. Concern about this interaction means many people wait 20 minutes or more before applying another skin care product. Good news, you don't have to wait!
The reason you don’t have to wait is because once the pH range of a water-based product is established, it will hold within that range even when applied at the same time as products outside that pH range. That’s because the ingredients chemists use to establish a product’s pH range are strong enough to keep it within the desired range no matter what you apply at the same time.
It’s far easier to disrupt the pH of your skin than it is to do so to skin care products. In order to move the product’s pH out of its range or have it significantly alter the pH of other products, you’d need to add a lot of water (which means more hydrogen ions), heat, and time (we’re talking several days).
During normal use, it’s chemically impossible for a higher-pH product to make a lower-pH product ineffective, and the reverse is also true. You can gain the visible benefits that all of these ingredients provide; no need to adjust your skincare routine!
Is Sparkling Water Compatible with Your Skin’s pH?
There have been concerns recently that washing with regular tap water can disrupt skin's pH, and that you should wash with sparkling water instead. The issue is based on tap water having a pH of 7 and being perceived as too high for skin’s pH of 5.5 to 4.5. The claim is that because carbonated or sparkling water has a pH of 5.5, it’s more compatible with the skin.
Though this sounds reasonable, using regular tap water is not an issue for a couple of reasons. First, most sparkling water doesn't have a pH of 5.5, and instead has a pH between 3 and 4. But even if sparkling water had a pH of 5.5, that's still higher than most people’s natural pH. Second, a neutral pH of 7 (which is what tap water has) is less disruptive of skin’s natural pH than any other pH number. Long story short, it's just fine to wash your skin with plain old tap water!
Shop online for Paula’s Choice pH-friendly skincare products today!
References for this information:
Current Problems in Dermatology, August 2018, pages 1-10
The Journal of Clinical and Aesthetic Dermatology, July 2017, pages 33-39
Acta Dermato-Venereologica, March 2013, pages 261-269
Photochemistry and Photobiological Sciences, April 2010, pages 578-585
Handbook of Cosmetic Science and Technology, August 2022, chapter 36
Journal of Investigative Dermatology, March 2025, pages 509-521
Folding and Design, August 1998, pages 285-291
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