The Final Word on Whether Antiperspirant Is Safe

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The rumored dangers of antiperspirants make a lot of people nervous. Maybe you're sweating just thinking about them: Since the '60s, studies have linked aluminum, the active ingredient in antiperspirants, to several degenerative and chronic diseases.

Here's the deal: Two types of sweat glands saturate your underarms. The eccrine glands produce sweat, which escapes through pores on the skin's surface. The apocrine glands merge with hair follicles under the surface. Fluids from these glands mix with bacteria (your warm, dark, moist pits make the perfect breeding ground for bugs) and produce the unpleasant stench we call body odor.

Deodorants simply perfume your pits, but antiperspirants contain aluminum salts that temporarily clog the pores and keep sweat from escaping in the first place, says Malcolm Brock, medical director for the Center for Sweat Disorders at Johns Hopkins Medicine. People fear the body absorbs this aluminum, which then theoretically interferes with cells to cause disease. But the science is inconclusive.

In 1965, researchers discovered that rabbits injected with a solution containing aluminum phosphate experienced brain degeneration. Conflicting evidence ensued: One study found high levels of aluminum in the brains of deceased Alzheimer's patients, but a systematic review found no "clear evidence" that antiperspirants increase your risk of the disease.

Another paper bred fear when it found most breast cancers develop in the area of the breast closest to the armpit. While one study discovered a link between antiperspirant use and breast cancer diagnosis, another found no relationship at all. Aluminum is toxic in extremely high doses, but the question remains: Does your body absorb enough from antiperspirants to justify scrapping your stick?

"That's just not biologically feasible," says Teri Greiling, an associate professor of dermatology at the Oregon Health & Science University. "You're not absorbing your antiperspirant. Your skin is biologically designed to keep all the bad things out, and it actually does a great job at that. It's a really good barrier."

People may see the armpit as extra vulnerable to aluminum absorption because of its high concentration of sweat glands, Brock says, but pores only open at the surface of your skin. Beneath the surface, your pores, at their base, remain sealed. That means that even though they become clogged with antiperspirant, your pores are not open channels for chemicals to pass through freely.

Plus, you'd need to ingest or absorb enormous amounts of aluminum to experience its neurotoxic effects. Adults in the United States eat about seven to nine milligrams of aluminum per day from foods, but that doesn't cause any alarm. And researchers have to infuse aluminum directly into rats' bloodstreams for several years before they see any effect, Greiling says. "So what we're exposed to by smearing a little antiperspirant into our armpits is not even comparable."

One thing antiperspirants do change: the bacteria that grow on your skin. Research published last year shows that people who use antiperspirants have fewer bacteria growing in their pits than people who regularly apply deodorant or nothing at all. And Corynebacteria, the type responsible for body odor, only made up 14 percent of the bacteria found in antiperspirant-users' pits compared to 62 percent for people who go au natural.

The caveat: Corynebacteria make you smell, but they may also protect us from pathogens, so having fewer of them isn't necessarily a good thing. "You're making the environment less hospitable for bacterial growth, which is the overall goal, because that's where the smell comes from," Greiling says. "Our microbiome does wonderful things for us, but there's no reason why changing the balance in this one area would lead to a long-term detriment."

The fear-mongering persists online despite the lack of evidence and the statements discrediting these claims. The National Cancer Institute cites "no scientific evidence" linking antiperspirants to breast cancer development. The Alzheimer's Association states "studies have failed to confirm any role for aluminum" in causing the disease. In fact, the FDA recently proposed a ban on triclosan, an antibacterial antibiotic in many hand soaps—and deodorants. "Because of the triclosan, I never recommend deodorants over antiperspirants," Dr. Greiling says. "I shy away from them. I'm wary of them."

But health scares and the potential of developing disease can alarm us, and it's comforting to blame these conditions on something we can control. Lots of evidence shows that super straightforward habits like eating lots of fruits and vegetables, exercising, and avoiding animal fats decrease your health risks.

"But those lifestyle changes," Greiling says, "are harder to make than changing your brand of antiperspirant or deodorant."

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