Deodorant vs. Antiperspirant—Here's What You Need to Know

Spoiler alert: They’re not the same thing.

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Deodorant is one of those terms that gets used all the time, but, breaking news, not everything that you swipe under your arms is, in fact, a deodorant. Armpit products are categorized into two distinct groups, deodorants and antiperspirants, and they have one major difference. It's pretty simple, since it's all in the name: Deodorants prevent odor, whereas antiperspirants prevent sweat. Ultimately, whichever one you choose to use is a matter of personal preference, but here's what you need to know about both.

What Is Deodorant?

Long story short: Deodorants won't keep you from sweating. If you don't mind a little moisture under your arms and simply want to ward off B.O., then consider a deodorant. "They typically contain ingredients, such as fragrance, that mask the odor expressed in the underarms," says Alicia Zalka, MD, a board-certified dermatologist in Connecticut and the founder of Surface Deep. Most of them also contain ingredients that absorb moisture and/or slow down bacterial growth, adds Hadley King, MD, a board-certified dermatologist in New York City. (As a quick reminder, it's the bacteria that's responsible for the unpleasant smell, not the sweat itself.)

While deodorants have been trendy as of late, positioned as a more natural alternative to antiperspirants (more on why in a moment), it's important to remember that even the most natural of deodorants can contain irritating ingredients. For example, "Many natural deodorants rely on baking soda to absorb moisture and neutralize odor, but too much baking soda can cause skin irritation in some people," says Dr. King. And the fragrance in many can come from essential oils, which are a common cause of allergic contact dermatitis, she adds.

At the end of the day, because none of the ingredients in these formulas are going to actually block eccrine (aka sweat) ducts, the efficacy as to how much moisture they can absorb will vary from person to person, notes Dr. King. So if you are going the deo route, just bear in mind that you may have to get used to feeling a little damp under your arms.

What Is Antiperspirant?

Antiperspirants do prevent sweat, but there are questions about the ingredients they use.

Any antiperspirant is going to contain some type of aluminum salt compounds—common ones include aluminum chlorohydrate, aluminum zirconium, and aluminum chloride—all of which work by blocking the sweat ducts by forming a plug when they get mixed with sweat droplets, thereby preventing perspiration, says Dr. Zalka. Sweat flow is impeded and the skin is kept drier, she explains.

But you've probably heard some not-so-great things about aluminum, as it's garnered a bit of a bad reputation as of late. "Aluminum has been linked to Alzheimer's disease and to breast cancer, but whether or not the aluminum in antiperspirants contributes to these conditions is not yet definitively known, and there is no research data showing this," says Dr. King. Both she and Dr. Zalka underscore the fact that even the American Cancer Society has not proven a direct cause and effect between antiperspirant use and a higher risk of breast cancer. (In fact, according to the ACS, "There are no strong epidemiologic studies in the medical literature that link breast cancer risk and antiperspirant use, and very little scientific evidence to support this claim.") So while you may hear a lot about this correlation, take it with a grain of salt.

The one time you should definitely avoid using aluminum-containing products, such as antiperspirants, is when receiving a mammogram; the tiny metallic crystals in the products can impede the optimal reading and interpretation of breast imaging studies, Dr. Zalka explains.

So, which one should you use?

Again, it's a matter of personal choice and comfort level. While the data proving any problems with aluminum is low, many antiperspirants do contain other ingredients, such as triclosan, propylene glycol, and parabens, which come with their own set of concerns, notes Dr. King. And, as Dr. Zalka points out, your body is made to sweat—it's a normal regulatory function. That being said, if you really don't like feeling wet, and/or sweat excessively, then an antiperspirant is the only thing that's guaranteed to keep you dry.

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