5 reasons your armpits suddenly smell so bad and what to do about it (2024)

• Your armpits have an inherent odor that's totally normal due to apocrine and eccrine glands.
• Everyone's armpits smell different thanks to genetics, hormones, diet, and other factors.
• If your armpits suddenly smell especially foul it could be a sign of an infection that needs medical attention.

Everyone's underarms have a certain smell to them, and most of the time it's completely normal and not a cause for concern.

Body odor comes from a couple of things:

• Apocrine skin glands. These scent-emitting glands become active during puberty and are highly sensitive to hormonal fluctuations. Apocrine glands in your underarms contribute to stinky pits, but you'll also find them around the groin.
• Eccrine glands. These glands, which are all over your body but concentrated in the underarms, produce liquid. When you sweat — which everyone does — the bacteria and other microorganisms that are a healthy part of your skin become moist and give off a smell.

"There is no typical smell because it can differ from person to person and can be influenced by genetics, foods, hormones, hygiene, and medications among other things," says Susan Massick, MD, a dermatologist at The Ohio State University Wexner Medical Center.

The only time your B.O. may be a medical problem is if it has an especially foul odor that could be a sign of an infection. Other than that, the only thing you risk from having smelly armpits is that people around you may get grossed out by your smell, says Brian Toy, MD, a dermatologist at Providence Mission Hospital.

Here are five common causes of suddenly smelly armpits, how to stop the stench in its tracks, and when it's time to see a doctor.

1. Diet

As your body breaks down food, chemical compounds reach your apocrine glands where they can then be secreted as body odor. Therefore, what foods you eat can influence how you smell.

In particular, foods with especially pungent flavors are linked to strong body odor and include:

• Sulfurous foods like red meat, onions, garlic, broccoli, cabbage, and cauliflower
• Spices including curry, cumin, fenugreek, garlic, and coriander
• Alcoholincluding beer, wine, and hard liquor

By contrast, a small 2017 study found that females preferred the scent of males who ate lots of fruits and vegetables.

Yet Toy says not to adjust your diet in hopes of smelling better to the opposite sex. "Diet is only one contributing factor to body odor," he says.

2. Excess sweating

Conditions that cause excess sweating, known as hyperhidrosis, can increase body odor. Hyperhidrosis has many causes, including:

• Anxiety
• Infection
• Cancer and other diseases
• Stroke
• Thyroid condition
• Menopause

If you sweat a lot, the moisture caused by extra sweat promotes bacterial growth, Toy says. In addition, the apocrine glands are more active in people who have hyperhidrosis, he says.

3. Puberty

Children don't have active apocrine glands, which is why they don't have body odor, says Toy. But during puberty the apocrine glands become active, which causes the uptick in scent that many people going through puberty experience.

Since body odor is new territory for many tweens and teens, they may not yet know how to control it through proper washing, wearing deodorant, and frequently changing clothes. That can make matters even stinkier. "Hygiene probably plays the biggest role," Toy says.

4. Hormonal changes

Hormonal changes can also impact your body scent, whether they're caused by the menstrual cycle, pregnancy, or menopause.

During pregnancy, people are more likely to sweat, but their apocrine glands are less active, which can change scent overall. Biological changes may also be at play: A small 2020 study found that males perceived female body odor as more pleasant during ovulation.

"In the animal kingdom, body odor changes during ovulation to attract a mate and increase the odds of conception," says Toy. There's little research about changes to scent during the menstrual cycle in humans, but lots of anecdotal evidence.

5. Gender transition

Testosterone is linked to sweating, especially from the apocrine glands, says Toy.

"Anyone taking testosterone supplementation will be more predisposed to body odor," he says.

That includes trans men, who often notice a stronger body odor and more sweating within three months of beginning testosterone therapy.

Trans women may also notice changes to their body odor, but it's more likely to be a decrease as testosterone levels drop.

Treatment and prevention

The best way to treat foul-smelling armpits is to practice good hygiene, says Toy:

• Shower daily. Wash your armpits with an antibacterial soap. This will help minimize bacteria on your skin that react with your sweat causing odor.
• Use antiperspirant. Antiperspirant stops sweating, as opposed to deodorant, which just masks scent. Apply antiperspirant at night, to allow it to absorb while you sleep.
• Shave your armpits. Hair traps sweat and bacteria, and can increase scent.
• Wear wicking, breathable clothing. Clothes that keep you cool will reduce sweating, which should reduce odor.
• Adjust your diet. If you notice certain foods make you smell, consider cutting those out or cutting back, says Massick.

If you try all of that and still have a bad odor, Toy recommends trying an antimicrobial wash with 4% benzoyl peroxide on your armpits. That can remove bacteria and fungus, and reduce scent.

When to see a doctor

If you have a sudden, unexplained change in body odor that doesn't respond to a solid hygiene routine, see a doctor, says Massick.

"If you feel it is out of proportion or unable to be controlled, then seek medical advice for tips to help combat it," she says.

Certain medical conditions can lead to foul-smelling armpits, including:

• A yeast infection or rash on the skin
• Bromhidrosis, a chronic foul body odor
• Erythrasma, a bacteria skin infection

To treat these, you may need a prescription antibacterial cream or other medication, Toy says.

Insider's takeaway

Body odor happens when sweat interacts with bacteria on our skin, and when the apocrine glands in your armpits secrete scent.

Changes to body odor can happen due to diet, hygiene or hormonal fluctuations. If you or a loved one is offended by your odor, a solid hygiene routine and working with a dermatologist can help, says Massick. However, it's also important to remember that body odor is to be expected.

"Remember that body odor is perfectly natural and completely normal," says Massick.