The basic difference between antiperspirants and deodorants is that the former keeps you from sweating while the latter cuts down on what makes you stink when you do sweat. To get to the nuts and bolts of the difference, though, you'll have to learn a little armpit anatomy. There are several sources for our natural scent. The most prolific perpetrator is the underarm. The scent produced here is called axillary body odor (named after the medical term for the underarm, axilla).
You've got two types of sweat glands all over your skin, and they're both found most highly concentrated in your underarm. These glands don't generally begin to develop until humans hit puberty, so most people don't produce body odor until around age 11 or 12 [source: Greenberg]. The eccrine glands act to cool you off when you're hot. These glands excrete only water and salt and have nothing to do with your troublesome body odor. The apocrine glands are the culprit behind your terrible smell. These glands carry secretions of fats and proteins from within your body, along with your sweat, to the exterior surface of your skin. Here, these fats and proteins react with bacteria to create an odor [source: Lynn].
Deodorants don't have any reinforcements to keep you from sweating -- once you apply deodorant to your axilla and go play basketball, you're going to perspire. But deodorant does work to counteract the smell that's produced after the fats and proteins emitted from your cells migrate to the surface of your skin. Deodorant targets the bacteria that hang around your armpits. Ingredients like triclosan in deodorants make the skin in your underarm too salty or acidic to support the indigenous bacteria that are meant to thrive there [source: Truitt]. Without any bacteria to feast on the proteins and fats delivered through your sweat, no smell is produced.
Antiperspirants cut down on body odor using the exact opposite principle: They actually keep you from sweating. Without any sweat, the bacteria found in abundance in your underarms don't have anything to eat. Most antiperspirants have some of the same ingredients found in deodorants that kill bacteria as a failsafe [source: Unilever]. Their main function, however, is to keep you from perspiring. They do this through ingredients like aluminum and zirconium, which plug the sweat glands found in your underarms [source: Ramirez]. When you apply antiperspirant, it's literally no sweat.
There may be drawbacks to not smelling like you're meant to, however. Some studies have found a link between breast cancer and antiperspirants. The aluminum found in antiperspirants has been shown to cause DNA mutation, a requisite for uncontrolled growth of cells (cancer) [source: Darbre]. Other studies have refuted this claim, and reproducing results has been hit or miss -- the link remains inconclusive [source: National Cancer Institute]. Equally troubling and mysterious is the warning label found on antiperspirants that suggests the user consult with a physician before using the product if he or she suffers from kidney disease [source: CBS News]. Aluminum can prove fatal in large enough doses to people with impaired kidney function [source: KOMO].
It's a risk many people are willing to take, judging from all the options on the market. Of course, you could buck the entire system by not wearing deodorant at all.
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