How Does Antiperspirant Actually Work, Anyway?

A chemist explains the ingredients in antiperspirant that stop your sweat glands from spraying.


Let’s set the record straight: While there are antiperspirant deodorants out there, antiperspirants and deodorants aren’t one and the same. In fact, according to chemist and product wiz Fadi Mourad, these two chemical compounds—while often combined into a single product—function very differently when applied to the skin. Below, he explains the science behind how antiperspirants and deodorants keep your pits dry and fresh.

How Antiperspirant Works
Aluminium chloride compounds—like aluminium zirconium tetrachlorohydrex gly—are the most common active ingredients found in antiperspirant deodorants on the market today, according to Mourad. These compounds mix with sweat (or any other moisture found on the skin) to form a gel-like plug that blocks the sweat glands and causes them to shrink. The more pores this mixture plugs, the less you’ll sweat, which is why it’s important to make sure you’re fully covered. Of course, this so-called plug is temporary—it will eventually come off as the skin sloughs, and your pits will proceed to make it rain until you reapply.

“Antiperspirants should only be used under your arms [since they’re designed to clog pores, which will likely result in acne and boils elsewhere] and applied in an even layer on dry skin,” Mourad explains. “Then, you should allow the antiperspirant to dry before putting a shirt on.” Applying an antiperspirant to dry skin gives the aluminium chloride compounds a chance to seep into the pores and better plug the sweat glands. This is why it’s usually better to shower and apply antiperspirants at night: You’ll have 15 or 20 minutes to wait until you’re completely dry before applying the antiperspirant, rather than applying your antiperspirant directly after showering during the morning rush.

How Deodorant Works
Deodorants, on the other hand, don’t really do much of anything to keep you from sweating (although, like we mentioned earlier, there are a ton of antiperspirant deodorants out there that do both jobs). Instead, they usually contain alcohol-based ingredients that kill off the odour-causing bacteria in your armpit—the little critters that feed off of the moisture there—before they have a chance to stink up the area.

In more straightforward terms, antiperspirants prevent sweating, while deodorants prevent odour. If you come across “clinical-strength” deodorant, know that it just contains more of the active ingredient (usually alcohol) than regular deodorant—therefore, it provides more protection against odour.

One thing to be aware of when using antiperspirants (or antiperspirant deodorants) is that a small portion of the population is allergic to aluminium. For them, applying such products can result in itchiness, redness and inflammation. If you happen to be one of those folks, we recommend visiting a dermatologist for aluminium-free recommendations that work for you (and your pits).