In 2018, blogger and writer Tracey Robey wrote a story for Racked suggesting that acids (think: glycolic, lactic, etc.—the same ones we put on our faces) might also make the best deodorants. The headline “The Best Natural Deodorant Is Acid,” made a bold claim, especially because it represented an actually novel idea. Flash forward two years and some of the most popular brands are introducing their first natural deodorant formulas. Being "natural" means that what they don’t have, of course, is aluminum—what they do have is a variety of the acids, suggested by Robey.
It’s sound science, according to dermatologist Joshua Zeichner, MD. “The idea of acid-based deodorants is that they decrease the pH of the skin to make it an inhospitable environment for odor causing bacteria. While they will not reduce sweat, they may reduce odor,” he explains.
Let's get this straight: It's not your sweat that smells—it's the bacteria.
Before we can talk about ingredients in deodorant and what makes them effective (or not), here’s what you need to know: Sweating allows us to maintain our core body temperature. “As sweat evaporates from the surface of the skin, it cools down our bodies,” Dr. Zeichner explains.
Traditional antiperspirants are designed to reduce sweat, not just deodorize it. That usually happens as a result of the aforementioned aluminum—which plugs, or blocks the sweat gland preventing sweat from passing through to the surface of the skin. As a reminder—sweat on its own is odorless, but Dr. Zeichner explains, “when it's broken down by natural bacteria on the skin it gives off a fowl smell.”
Natural deodorants simply de-odorize, they don't prevent sweat.
Deodorants, on the other hand, “don’t address wetness and are designed only to neutralize odor,” Dr. Zeichner says. Rather, they use fragrance to mask odor, or use ingredients that lower the level of odor-causing bacteria on the skin.
For the past few years, many consumers who’ve decided to go for aluminum-free formulas have gone looking for their perfect match, or deodorant equivalent of Cinderella's glass slipper. Of course, there is no one option that works for everyone.
Initially, most natural deodorants included baking soda high on their ingredient lists. “Baking soda (sodium bicarbonate) has long been used to absorb and neutralize odor. Though it’s not clinically tested, the theory is that since most odors have higher pH levels, baking soda and its low pH neutralizes whatever is causing the odor,” explains Sarah Moret, founder of clean body care line Curie. Other common ingredients, to name a few, include essential oils and natural extracts like sage (which is antifungal), tea tree oil, and coconut oil (both anti-bacterial). Baking soda is often omitted from “sensitive skin” formulas, as it can be irritating to some—this is because an excess of baking soda in a formula can be too alkaline. That is to say: “if your skin and/or sweat are especially acidic and you mix it with a basic substance like baking soda, it can cause a reaction,” Moret explains.
That's where acids come into play. For Randi Christiansen, CEO and co-Founder of Necessaire, the cult-favorite body care line that just launched its first deodorant—acid-based deodorants are “a new, modern alternative to combat odor.” Again, it comes back to the pH. “We believe acids help lower the skin's pH under the arm, which helps create an environment where odor-causing bacteria are less prone to flourish,” Christiansen says. In Necessaire’s cream-based formula, this is done with a blend of mandelic and lactic acids to combat odor, while a multi-mineral complex (silica, zinc, kaolin clay) helps keep things dry.
Mandelic acid is also used in Drunk Elephant’s deodorant debut, Sweet Pitti Deodorant Cream. “We didn’t want to use baking soda, because that would have made the pH level far too high for skin—baking soda has a pH level of 9+—and is potentially sensitizing,” explains Drunk Elephant founder, Tiffany Masterson, of her decision to keep the brand’s deodorant baking soda free. “We’re all about using only ingredients that support the health of the acid mantle, also known as the skin barrier,” she says, “and a big part of that is formulating to support the naturally acidic pH of skin, which is around 5.5. That’s why we chose mandelic acid—it’s an effective antibacterial that is gentle to skin and won’t disrupt the acid mantle.” For a deodorant to actually deodorize, it has to be able to kill the bacteria that makes sweat stink, before it breaks down on the skin’s surface."
Two other recent entrants to the natural-deodorant-with-acid space include Kinko and Surface Deep—Kinko adds pre-and-postbiotics to the mix of key ingredients, while Surface Deep uses probiotics. Of this, Moret notes that “Early research shows that "good bacteria" can help combat odor. It is also an effective natural preservative.”
In Surface Deep, it’s a mix of fruit-derived glycolic acid which inhibits bacteria-causing odor and skin-soothing probiotics, which founder, dermatologist, Dr. Alicia Zalka explains, work together to achieve balance. “A healthy physiology,” she says, “particularly with the skin, is all about balance.” The biodegradable “Anti-Odorant” pads (here’s where the Stridex comparison is the most literal) come in a box set of 30 and were inspired by Zalka’s experience subbing in a glycolic pad when she found herself out of deodorant, with the hypothesis that, in a pinch, the “deep clean” might also prevent odor.
Kinko uses a patent-pending blend of ingredients called Microbiomix, which co-founder Fanny Coste describes as “a blend of proven ingredients that work with your skin’s microbiome, nurturing the good bacteria and neutralizing the bad.” Essentially, prebiotics feed the good bacteria and help them thrive and “outgrow odor-causing bacteria,” while, postbiotics adjust the skin’s pH to its “physiological level,” and of course, lactic acid.
So, is it worth the fairly steep $16-$26 (!) one of these new formulas will cost? Not only is the jury still out, but, it might take some trial and error to actually know what works best for your skin—and individual microbiome. For sensitive skin types, however, there could definitely be a benefit—“the formulation of the acid based deodorants are designed to be gentle on the underarm skin,” Dr. Zeichner says, “while traditional acids used for your face may help under the arms as well, I would be cautious that they may cause too much irritation, leading to more harm than good.”
The TL;DR: acids are antibacterial and can contribute to killing odor.
But in the newest deodorant formulas, they’re not working alone. Absorbent ingredients like arrowroot and kaolin clay aid in keeping things dry, while in some formulas, pre, post, and probiotics are used to achieve balance.
If you already use a deodorant that works for you, there’s likely no reason to hit ‘add to cart’ immediately, but, if baking soda irritates your skin, and you’re looking, but not finding an aluminum-free deodorant, you might want to add some acid to the mix.
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