Why Acid Works So Well as a Deodorant


Acid, believe it or not, works wonders as a deodorant.

When you think of the word “acid” you probably don’t imagine it as something you apply to your skin. Sure, there are some Grateful Dead fans who would jump at the opportunity to ingest it. But generally, acid, as an idea, seems sharp, biting, or even toxic.

We’ll get to the deodorizing powers of acid soon. But first: If you’re big into skincare or aware of your skin’s own delicate “pH balance”, then you know that acid refers to far more than toxic rain, Dead-Head hallucinogens, and lemon juice. On the one hand, your own skin is acidic, in that it sits somewhere around 5 on the 0-14 scale of Acidic (0) and Alkaline (14). That’s just basic chemistry, and you want to apply products to your skin that preserve this balance and keep the skin ever so slightly acidic and left of neutral (7). (If this sounds like a foreign language to you, just know that this is the stuff skincare producers are concerned about when making products that prevent irritation and breakouts, and the like.)

This explains why many of the best products for your skin are acids since they keep things in harmony: hyaluronic acid, for example, helps your skin retain moisture, by absorbing water up to 1000 times its own weight. Then there are pore-unclogging acids like alpha hydroxy acids (called AHAs; water-soluble acids like lactic acid and glycolic acid) as well as beta hydroxy acids (BHAs; oil-soluble acids like salicylic acid). These both dissolve dead skin, improve skin texture, and can prevent acne. AHAs, in particular, are often antimicrobial, so they also kill off bacteria.

And guess what causes odors under your arm? Bacteria! It breaks down the sweat produced by your apocrine glands (they’re at your armpits, groin, and nipples) and produces that fabulous rank smell. (No, don’t put acids on your groin or nipples.)

“The whole point of using acids as a deodorant is because they decrease the pH (and increase the acidity) of your skin, making it less hospitable to bacteria,” says dermatologist Heather Rogers of Modern Dermatology in Seattle. “Skin likes to be a bit acidic to protect itself from the overgrowth of bacteria. Your sweat is a bit alkaline and can increase the pH of your skin, making it easier for bacteria to grow and it is the bacteria that makes you stink. So by using a deodorant that makes your skin more acidic again, you have less bacteria growing and are less stinky.”

Rogers offers one word of caution, however: “If the acid is too strong, you can irritate your skin and break down the skin barrier. So a little bit of acid is a good thing, but too much acid is a bad thing.” Luckily the people making your products—those same ones concerned with your pH levels and your own comfort with their assortments—are doing the groundwork to put manageable and responsible levels of acids in their deodorants—primarily AHAs like lactic and glycolic acid. (However, any chemical facial exfoliants that are super heavy in acidic ingredients will remind you not to apply them more than 2-3 times per week.)

As for some of our favorite deodorants with bacteria-fighting acid, consider either of the below:

Maapilim’s roll-on deodorant, $26 for one-time purchase, $18.20 bi-monthly subscription

Dr. Hauschka herbal mint roll-on natural deodorant, $24

Vichy roll-on deodorant for sensitive skin, $17

And, if you’ve already got a deodorant you like but want to apply a straight AHA solution to your skin, this could have the same bacteria-neutralizing effect. That is to say: Many AHA skincare products double as deodorizers under your arms. Just pay attention to the pH levels of any AHA product you use: The Ordinary’s toner ($8.70) uses 7% glycolic acid and carries an approximate 3.5 pH balance. So, since you want to keep your skin’s pH in the 4.5-5.5 range, you may upset the skin if you apply it to underarms (or the face) daily or excessively. Once every couple of days should suffice while using a different, more delicate deodorant on the days between.

However, you could instead by a pH-balanced daily toning pad with AHA, and swipe it under each arm for the same effect as many deodorants:

Replenix glycolic acid (AHA) and salicylic acid (BHA) exfoliating pads, 60 pack, $26