Is There Any Benefit to Having Armpit Hair and Armpit Odor?

Armpit hair traps odor-causing bacteria, which makes our underarms smell. Those scents can help shape our perception of those around us.

Armpit hair is natural, and whether you shave it, trim it, or let it grow, what you do with your armpit hair is a choice all your own. And while that may be so, you might also have found yourself wondering, why on earth do humans even have armpit hair? What purpose does it serve? And is there any benefit to keeping it?

To find out more, Health contacted American Academy of Dermatology board-certified dermatologist Shani Francis, MD, a clinical assistant professor at the University of Chicago Pritzker School of Medicine and medical director at Ashira Dermatology.

After talking with Dr. Francis, it's clear that armpit hair does, in fact, serve a purpose—and it's one you might not expect.

Traps Odor-Causing Bacteria

"Armpit hair is a collecting site to help bacteria grow," Dr. Francis told Health. "It's a place that can hold sweat and help give off this odor."

A 2016 study published in the Journal of Cosmetic Dermatology backs Dr. Francis' statement up. The study aimed to find out if armpit hair affects body odor, and if so, to what extent. Before the study began, researchers theorized that removing armpit hair would be the best way to minimize armpit odor.

To test their theory, the researchers put together four groups of men based on what they do with their armpit hair:

  • Group 1 trimmed their armpit hair with scissors
  • Group 2 shaved their armpit hair with a razor in the shower
  • Group 3 waxed their armpit hair
  • Group 4 left their armpit hair untouched

Participants in all groups were asked not to wear deodorant or antiperspirant (aka anti-sweat), perfumed products, medicines, or deodorant soaps on their armpits, and to go about their normal activities as usual. The goal was to maximize each participant's natural body odor, with the only changing factor being their armpit hair (or lack of it).

By the end of the study, researchers concluded that men who removed their armpit hair by waxing it off or shaving it with a razor had the least body odor. Those who simply trimmed their armpit hair had the next smelliest, with the strongest armpit odors coming from those who left their pit hair untamed.

An important highlight from the study was that subjects who removed their armpit hair had the cleanest armpits. Just as this 2018 review in the journal Microbiome points out, sweat by itself is not odorous. It's the bacteria in your armpits that causes odor—bacteria that thrive in warm, moist places (your pits) and get especially "trapped" in the hair that grows there.

Affects How You Perceive Others

Whether it's your favorite meal or last week's trash, a smell can be intoxicatingly good and equally as bad, if not worse. Some people might even go so far as to say that how a potential mate smells is a make-or-break factor in whether they will pair up. "It's nasty," Dr. Francis admitted, "But it's cool!"

Even beyond romantic attraction, there is enticing evidence that an individual's body odor hints at aspects of their personality to others.

For a 2013 study published in the journal PLoS One, researchers asked male subjects to smell the body odors of two groups of women: women who do wear antiperspirant (anti-sweating) deodorant and women who don't wear antiperspirant deodorant.

Overall, the males preferred the smells of women who do wear deodorant—rating them as more confident, trustworthy, and level-headed in stressful situations than their non-deodorant-wearing counterparts. The researchers also concluded that different body odors emit different social signals and that those signals can be "actively changed by the sender," i.e. by wearing deodorant and washing up.

Armpit Odor Emits Fertility Cues

If you have ever had a period, then you know how much your body can change over the course of one month. Any number of reasons can cause hormones to fluctuate. These fluctuations largely influence how much you sweat and, therefore, how wet, moist, and optimal your armpits are for odor-causing bacteria to flourish.

A 2013 study published in Evolution and Human Behavior set out to investigate this phenomenon in real life. The study found that men tend to find women more attractive when they are at the "peak-fertility stage" of their ovulatory cycle. But it's not just men who have a hound-like sense of smell. Women also tend to prefer the body odors of men with the highest testosterone levels, a finding published by PLoS One in 2020.

"Different people make different odors, and believe it or not, odor is an attraction to the opposite sex," Dr. Francis told Health. "One of the first signs of puberty is hair developing in the underarms and groin." Plus, armpit hair often gets thin and sparse after menopause when a woman no longer ovulates, according to a 2020 review in the journal Nature.

Removing Armpit Hair

For one thing, there's nothing wrong with wanting to get rid of your armpit hair. If that's something you're considering, there are plenty of different options available, starting with manual hair-removal options.

Manual hair-removal methods are ones that you can do by hand. They're quick and usually cheap, but they can be irritating—physically and emotionally. They include threading, which entails removing hair with a piece of thread, and sugaring, in which a sugar water mixture is applied to unwanted hair then all of it is peeled off together. Shaving and waxing are also manual methods.

"You can get ingrown hairs, and you have to shave practically every day," Malika Sloan, a medical aesthetician at Tribeca MedSpa in New York City, told Health. There are also chemical options like hair-removal creams that dissolve, Sloan added. They're not too pricey either, but they can be irritating for sensitive skin.

If you are looking for a more permanent hair-removal option, there are a few energy-based methods, like lasers and microwaves (no, not the kind in your kitchen), but those can be more expensive and sometimes require multiple office visits.

Opting for laser armpit hair removal usually means you're in for 6-10 treatments about 6-8 weeks apart, said Sloan. Microwave technology "kills" the sweat glands and destroys hair follicles at the same time. As one 2020 study in Dermatologic Surgery found, the microwave method can result in about 80% less sweating and about 70% less hair growth. "We have clients who don't even wear deodorant anymore," Sloan added.

Does Removing Hair Decrease Body Odor?

Here's the thing. Armpit hair by itself doesn't smell. Sweat by itself doesn't smell. But the odor-causing bacteria in your armpits? Yep, that'll do it.

"Cutting the hair only removes, let's say, the 'house' for the bacteria," Dr. Francis explained. The bacteria themselves remain, she said, so "if you have no armpit hair but don't wash your armpits, you're still going to have odor."

Ultimately, whether you have armpit hair or not, the important thing is that you stay on top of your personal hygiene to minimize odor-causing bacteria. That means cleansing regularly, wearing deodorant if you choose to, and letting your healthcare provider know if your body odor concerns you.

A Quick Review

The smell from armpits is caused by bacteria that thrive in warm, moist places. Armpit hair is a collecting site to help bacteria grow. An armpit is a place that can hold sweat and help give off this odor.

Researchers have found that an individual's body odor reflects aspects of their personality to others. Different people make different odors, and odor is an attraction to the opposite sex.

If you would prefer to remove your armpit hair, there are plenty of different options available. However, removing the hair only removes the 'house' for the bacteria. The bacteria themselves remain, so if you have no armpit hair but don't wash your armpits, you're still going to have odor.

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