Armpit Sweat: Why Does It Smell?

by Dennis Madden

Unpleasant Smell.

Sweating keeps you cool and that's important. What about armpit sweat and why does it seem to smell so much worse than the sweat that comes out of your hands or on your brow during a workout? Worse yet, why does it seem like the most offensive armpit odor appears when it's essential for you to be cool and confident?

What Makes Armpit Sweat Unique?

First, you should know that the sweat glands under your arms are different than those that cover most of your body. Most of your body sweat comes from eccrine glands, which secretes sweat made up of mostly water, according to the Mayo Clinic. The watery sweat is intended to cool the surface of the skin as it evaporates.

The sweat glands under your arms are a whole different beast. Apocrine glands secrete a milky fluid higher in protein and fat. Why does this matter? Sweat itself doesn't smell, says the National Institutes of Health. It's bacteria found on your skin that eats the sweat and produces smelly molecules that causes body odor, and the underarm area gives bacteria a perfect place to hide out. Basically, your underarm bacteria is eating your sweat and releasing out BO. Cool, right?

Why Do Sweaty Armpits Strike at the Worst Times?

If you sweat to keep cool, then why do you sweat when you're nervous, even if you're not physically active? The sympathetic, or fight-or-flight, nervous system is responsible for getting your body ready for incredible feats of strength when it perceives you're in immediate danger: get ready to rumble! ... or run really fast in the opposite direction. Part of this preparation includes sweating. Due to the body's hard wiring, anxiety and nerves from stressful social situations, like job interviews and first dates, can trigger this fight-or-flight response that the apocrine glands in your armpits are sensitive to.

What does all of this mean? Basically, when you're nervous, you're more likely to sweat from your armpits due to their sensitivity to stress hormones, compared to other areas of your body that are covered in eccrine glands, which are activated to keep your body cool. This is not to say you only sweat from your armpits when you're nervous. There's a major blood vessel, the axillary, close to the surface of your skin under your arms making them an effective site to apply the cooling power of sweat.

While not ideal for your social life, hopefully, this explanation at least makes things a little more interesting so you can accept your body for what it is. If you just need to manage a little body odor from your armpits, try a deodorant to help with underarm odor protection.

This article was brought to you by Colgate-Palmolive Company, the makers of Speed Stick products. The views and opinions expressed by the author do not reflect the position of the Colgate-Palmolive Company.