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Stop putting baking soda on your skin. Let me repeat that: Stop putting baking soda on your skin. Baking soda exfoliation is a total favorite of the home remedy set. I’ve seen it in a ton of places, including this article on what Emma Stone uses on her skin, and every time, it makes me cringe a little. Baking soda isn’t just ineffective, it’s actually damaging to your skin. Don’t believe me? Read below and see the science.
Baking Soda + Water is ALKALINE
Let’s start with a little chemistry lesson. Forgive me, chemistry buffs, since this will be information you already know. We’ll start with the Brønsted-Lowry concept, which says that acids are proton donators that are able to give a proton (the hydrogen cation or H+), and bases are proton acceptors that are able to receive a proton (H+). Bases neutralize acids by bonding with the acid’s hydrogen ion (General, Organic, and Biochemistry).
But, like it or not, the world is not a simple, black-and-white place of acids and bases. Thrown in there are also amphoteric molecules (ions). “Amphoteric” means that a substance has the ability to react with both acids and bases. And some of these amphoteric substances are also amphiprotic, which means they can donate and accept a hydrogen ion. Baking soda’s chemical name is sodium bicarbonate, and bicarbonate is an amphiprotic ion, so it can both take and lose a hydrogen ion. So, this means that baking soda reacts with acids and bases by either donating or accepting a hydrogen ion. But bicarbonate is a stronger base than it is an acid, so it’s more likely to accept a hydrogen.
When you’re making baking soda exfoliator, however, you’re mixing it with water, so the question is what’s the final pH of bicarbonate (HCO3-) and water (H2O). Here’s the chemical formula:
HCO3- + H2O → H2CO3 + OH-
See what happens there? Because it’s a stronger base, it tends to create HO-, rather than H3O+. What this means is that when you dissolve sodium bicarbonate in water, the solution tends to be more alkaline.
See That It’s Alkaline for Yourself
To really prove this, I decided to test it out and mix baking soda with water and test the pH to show you.
When we mixed baking soda and water (more than you’d use for a scrub) and tested it, the pH was about 8.
So Why Is Something Alkaline Bad for Skin?
The pH of the products you use is super important for maintaining healthy skin. Here’s how the pH scale works: It runs from 0-14 with 7 meaning neutral. Anything above 7 is considered alkaline, or a base, and anything below 7 is considered an acid. The skin naturally falls somewhere around 4.5 to 6.5, and is maintained by sebaceous glands, sweat glands, and normal skin flora, among others. This skin acidity is called the “acid mantle” (Exogenus Dermatology).
When you apply a product with a high pH, aka something alkaline, negatively disrupts the skin barrier. A study on skin products found that using an alkaline cleanser, even once, can do damage to the skin (Dermatology). An alkaline cleanser disrupts the skin’s acid mantle (affecting the skin barrier), and changes the bacterial flora composition on the skin and the activity of the enzymes in the upper layers of skin, as these have an optimal pH level. And the damage is cumulative: The longer you use it, the more damage it does to your skin.
So, with baking soda and water, you’re already disrupting the acid mantle, but you’re also manually exfoliating, making it even more damaging and drying.
Because of this, you want mildly acidic products, which help the skin hold moisture and also improve the skin barrier. But it’s important that they’re mildly acidic, as you can, in fact, go too low. If you go too low with products, you risk skin irritation, sun sensitivity, and hyperpigmentation (International Journal of Cosmetic Science). That’s why we don’t recommend that you use straight lemon juice on your skin, for example.
Skip the baking soda skin exfoliating and stick to something gentler with a lower pH. This is why I highly recommend sticking to professionally formulated products for your beauty routine. It’s not that I don’t love a good home remedy, but I think it’s easy to become misinformed and misuse products like baking soda in ways that does more harm than good.