Here’s Why You Might Be Getting an Armpit Rash From Deodorant

If you’ve ever switched to “natural” deodorant—you know, one that touts its organic, plant-based ingredients or “nontoxic” formula—and ended up with a gnarly rash, you might’ve been a tad perplexed. After all, a “natural” product should work in perfect harmony with your skin, right? Not exactly.

“Natural and nontoxic don’t mean side-effect-free,” Maral K. Skelsey, MD, clinical associate professor of dermatology at Georgetown University, tells SELF. In fact, some people might find natural deodorants even more irritating than their traditional counterparts.

Before delving into the source of your itchy, irritated armpits, it’s important to understand the difference between deodorant and antiperspirant, even if they aren’t marketed as natural products. Although they both have the same goal of keeping your underarms odor-free, they use different substances and mechanisms to get your pits to peak freshness.

A deodorant simply aims to block or mask odor—sometimes by overpowering the smell with a different scent—and sometimes helps decrease the number of bacteria without stopping sweat, Macrene Alexiades, MD, PhD, associate clinical professor of dermatology at Yale University, tells SELF. On the other hand, an antiperspirant is designed to physically block the release of sweat or perspiration. When it comes to traditional deodorants and antiperspirants, the ingredients are “classified as a drug, usually aluminum chloride that seals the sweat ducts,” Dr. Alexiades says, while natural deodorants typically use plant-based powders to help absorb moisture.

There’s usually no major harm in trying natural deodorant if you’re curious about it—just don’t expect the same results you’d typically get from an aluminum-based deodorant or antiperspirant, says Dr. Alexiades. And while any type of deodorant (or skin-care product, for that matter) can cause irritation or an allergic reaction that manifests as a rash, depending on your specific skin sensitivities, natural deodorants tend to pose a bit more risk. Here’s what you should know.

Back up: How does natural deodorant work?

Let’s quickly go back to the term “natural” deodorant. While the U.S. Food and Drug Administration (FDA) doesn’t regulate the term “natural,” when people think of natural deo, they’re typically thinking of deodorant that’s aluminum-free and usually coconut oil– or baking soda–based.

Look at natural deodorants in more detail and you’ll also find that many formulas are free from phthalates, parabens, or talc, while underscoring plant-derived ingredients that target various underarm concerns. For instance, tea tree oil, which is known for its antibacterial properties, per the Mayo Clinic, is often included, while other essential oils derived from bergamot or rosemary provide fragrance. Arrowroot powder and charcoal are also formulated in some natural deodorants to help absorb moisture, Hadley King, MD, clinical instructor of dermatology at the Weill Medical College of Cornell University, tells SELF. The latter boasts antibacterial benefits, she adds.

Other ingredients you might find include alpha hydroxy acids (AHAs), which are chemical exfoliators, like glycolic or lactic acids, that help dissolve dead skin cells.1 Another perk? “AHAs can lower the armpits’ pH levels, making the environment less hospitable to bacteria responsible for the odor,” Dr. King explains.

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Natural deodorants are often made with common irritants that can cause an armpit rash.

Natural deodorants often contain baking soda, or sodium bicarbonate, to help neutralize body odor. Its alkaline nature, which is more basic than the skin’s natural pH, can easily prompt a skin reaction, Neelam Vashi, MD, associate professor of dermatology at Boston University School of Medicine and director of the Boston University Cosmetic and Laser Center at Boston Medical Center, tells SELF. Due to baking soda’s well-known reputation as a potential irritant, some natural deodorant brands now offer baking-soda-free products for sensitive skin.

Other things to watch for on the label? Dr. Alexiades says vitamin E is a common ingredient that can irritate the skin or set off an allergic reaction. Other irritants or allergens can largely be found under the essential oil umbrella, such as limonene which can be found in rosemary extract, as well as lemongrass, lavender, tea tree, sandalwood, and peppermint oils, which are less likely to cause a deodorant rash but can still be culprits.