It’s that sweaty time of year — and most likely, you’re rolling on an extra layer of deodorant before stepping out into the sun. There’s no medical reason for us to cake our underarms with odor-fighting cosmetics; in fact, commercial deodorants were only popularized early in the last century. But today, the general public is so vigilant against body odor that the global deodorant market is projected to be worth nearly $31 billion by 2026.
Most deodorants fall into one of two categories: antiperspirant deodorant, which accounts for most mainstream drugstore brands, and non-antiperspirant deodorant, which is typically marketed as “natural.”
Antiperspirants may or may not be scented, but their stink-stopping power comes from a mighty (and mightily misunderstood) ingredient: aluminum. Every antiperspirant contains tiny aluminum salts that physically clog your sweat glands to prevent underarm sweat. No sweat means no odor.
Non-antiperspirant deodorants don’t contain aluminum, so instead of clogging those pores, they simply mask or neutralize unwanted odor with ingredients like baking soda, magnesium and essential oils.
Non-antiperspirant deodorants have become tremendously popular in recent years as consumers have gotten more interested in non-synthetic or “clean” cosmetic formulations. But just because they’re popular, does that mean they’re better than old-fashioned antiperspirants?
We asked board-certified dermatologists to weigh in on which types of deodorants are out there — and which they recommend to patients.
Antiperspirant deodorant
Antiperspirants are the gold standard of deodorants, and they account for the lion’s share of options lining drugstore shelves. That’s because they work: All contain aluminum, an active ingredient that inhibits the production of sweat.
For years, some have been concerned that the aluminum in these products can cause illnesses like breast cancer, but Dr. Viktoryia D Kazlouskaya, a professor of dermatology at the University of Pittsburgh, says there’s little evidence to support this. Even if aluminum was strongly linked to the development of breast cancer (which it isn’t), you aren’t getting very much from your antiperspirant.
“The absorption of aluminum through the skin is minimal,” Kazlouskaya says. What’s more, a 2013 study of cancerous breast tissue showed no indication that aluminum is linked to the disease.
That said, higher concentrations of aluminum may cause skin irritation in some users. Kazlouskaya recommends people with sensitive armpit skin steer clear of antiperspirants with labels like “extra strength” or “clinical strength” and stick to regular-strength varieties, which tend to max out at 15 percent aluminum content.
Baking soda deodorants
Most “natural” deodorant formulations target odor using a base of sodium bicarbonate, aka baking soda, the same stuff that makes your chocolate chip cookies chewy. On its face, this seems like a logical ingredient for combatting underarm stink. After all, baking soda works wonders removing odor from the insides of refrigerators and cat litter boxes.
But whether it’s an effective underarm deodorant ingredient simply hasn’t been studied in a meaningful capacity, Kazlouskaya explains. What’s more, the pH of baking soda doesn’t jive well with your underarm sweat.
Cosmetic dermatologist Dr. Ranella Hirsch of Cambridge, Massachusetts, says she’s seen “horror after horror” of “massive reactions” to baking soda deodorant. Plus, she adds, it can make you stink “to high heaven.”
Chapel Hill, North Carolina–based Dr. Chris Adigun is less adamantly opposed to baking soda deodorants. She says these ingredients might work for some people without causing irritation. “Just lower your expectations,” Adigun says; a baking soda deodorant probably won’t fight sweat and odor as effectively as the aluminum in your antiperspirant.
Magnesium deodorants
Non-antiperspirant deodorant formulations aimed at sensitive skin types often replace baking soda with some combination of magnesium hydroxide, arrowroot powder (or another moisture-absorbing starch, like corn), fragrance oils and an oily, skin-softening agent like caprylic triglyceride to bind everything to the surface of your skin.
Magnesium hydroxide has a similar pH to baking soda; you may have heard it called milk or cream of magnesia. Because it’s only slightly water soluble, it’s meant to dissolve slowly in your armpit sweat, potentially causing less irritation than the more water-soluble baking soda.
“It depends on how much you’re using it, but eventually [magnesium deodorants] could be irritating,” says Adigun. Residual grit from magnesium hydroxide and other starchy ingredients can also cause chafing.
Beyond the risk of skin irritation, there’s some evidence that higher pH levels, such as those found in magnesium and baking soda, actually encourage the growth of odor-causing armpit bacteria. At the end of the day, Adigun says, there hasn’t been enough research to make a definitive call just yet.
Coconut oil deodorants
Coconut oil and various coconut oil derivatives pop up in many non-antiperspirant deodorant formulations, either as a delivery vehicle for other active ingredients, like essential oils and starches, or as stars of the show. Proponents of coconut oil deodorant point to the antibacterial properties of its fatty acids. Since underarm stink is caused by bacteria, it makes sense that killing bacteria could reduce odor. Coconut oil is also generally safe, unless you’re allergic to coconut.
Does that mean we should be smearing coconut oil into our pits? Not quite, says Kazlouskaya. “It may possibly cause acne and ingrown hair because of occlusion of the hair follicles,” she says. “It also leaves stains on clothing.”
Essential oil deodorants
Essential oils derived from nice-smelling plants are used as fragrance in many deodorant products. In some popular natural deodorant sprays, they’re even the main active ingredient. But all the dermatologists we spoke with were quick to emphasize that essential oils can irritate the sensitive skin of your armpit.
Then again, some people’s skin may tolerate the small amounts of essential oils found in deodorants. These oils may even be effective in reducing odor, to a point. Adigun cites lavender oil in particular as a candidate for reducing the bacteria that makes us stink. More research will tell us either way. Until then, you’re much better prepared to read your deodorant’s ingredients list and get swiping.