I’ve been reading about the effects that skin pH has on our skin – mainly what happens when we increase the skin’s pH. Historically skin pH wasn’t seen as a foundational component to skin health, but more recent research seems to be indicating that it, in fact, is.
The enzymes kallikrein 5 and 7, β-glucocerebrosidase and sphingomyelinase are involved in sloughing of the skin, as well as creating skin lipids. They function best at certain pHs, and the pH gradient from close to pH 7 in the deeper layers of the skin to pH 4-6 in the upper layers of the skin modulates their function throughout the skin.
Bacteria found on our skin grow at different rates depending on the pH. Changing the pH of the skin can lead to the proliferation of certain species of bacteria. P. acnes bacteria and S. areus grow faster at a closer to neutral pH. Skin’s naturally produced antibiotic, dermicidin, is less effective at a closer to neutral pH as well.
An experiment where they lowered the pH of the skin found an enhancement of skin barrier function, measured by water loss through evaporation from the skin.
Low pH products may be especially important for people who have impaired skin function such as atopic dermatitis and acne.
This isn’t to say that pH is the only factor that produces benefits from a product, but it is one that should be considered. Some active ingredients may not be compatible with low pH. Niacinamide isn’t stable when stored in low pH solutions, and uncoated organic sunscreens like zinc oxide and titanium dioxide clump in acidic solutions reducing UV protection.
It can be difficult to accurately find out the pH of products at home, but I did come across this paper which examined the pH of various skin creams available in the US, and I thought it might be useful to share!
How they measured pH: A pea sized amount of moisturizer was placed on a piece of wax paper then measured with a Hanna HI 99191 probe at 25 °C. The measurements were taken 5 times and then averaged.
4.71 ± 0.01
Aquanil® Lotion
5.19 ± 0.04
Aquanil® HC
6.35 ± 0.12
Aquaphor® Ointment
6.82 ± 0.20
Aveeno® Daily Moisturizing Lotion
5.62 ± 0.01
Aveeno® Advanced Care Moisturizing Cream
6.35 ± 0.03
Aveeno® Positively Radiant Daily Moisturizer
5.54 ± 0.04
Aveeno® Skin Relief Moisturizing Lotion
4.88 ± 0.02
Aveeno® Skin Relief Moisturizing Lotion With Menthol
5.46 ± 0.02
Cerave® Moisturizing Cream
5.49 ± 0.02
Cerave® Moisturizing Lotion
5.68 ± 0.02
CeraVe® Facial Moisturizing Lotion PM
5.95 ± 0.01
Cetaphil® Moisturizing Cream
4.71 ± 0.02
Cetaphil® Restoraderm Skin Restoring Moisturizer
5.94 ± 0.02
Cetaphil® Daily Advance Ultrahydrating Lotion
5.65 ± 0.01
Dove® Day Lotion
6.47 ± 0.02
DML® Forte Body Moisturizing Cream
5.94 ± 0.08
DML® Moisturizing Lotion
6.55 ± 0.01
Epiceram®
5.45 ± 0.01
Eucerin® Calming Cream
5.41 ± 0.02
Eucerin® Menthol Itch Relief Lotion
4.81 ± 0.03
Eucerin® Original Dry Skin Therapy Cream
8.01 ± 0.04
Eucerin® Original Dry Skin Therapy Lotion
5.97 ± 0.03
Eucerin® Intensive Repair Body Cream
5.98 ± 0.03
Eucerin® Intensive Repair Body Lotion
8.19 ± 0.03
Neosalus® Cream
7.40 ± 0.10
Theraplex® Emollient For Severely Dry Skin
4.62 ± 0.18
Vanicream® Moisturizing Skin Cream
4.27 ± 0.05
Vanicream® Light Moisturizing Lotion
3.73 ± 0.03
Vaseline® Intensive Rescue Skin Protectant Body Lotion
4.30 ± 0.02
