Even copious amounts of deodorant and a devotion to perfume don’t guarantee that you won’t stink sometimes. Body odor is a normal occurrence, and when it’s not connected to a larger problem, you can attribute it to the mixture of sweat, bacteria, and environmental dirt that accumulates on your skin, Joshua Zeichner, director of cosmetic and clinical research in dermatology at Mount Sinai Hospital in New York City, tells Allure. “Body odor becomes stronger over time, as more bacteria and sweat build up on the skin, and they interact with each other,” he explains. “This is not harmful, as healthy bacteria live symbiotically on our bodies.”
But there are some body odors that fall outside of this norm. Some are totally benign, while others might signal that something is up with your health. “Many health conditions have signature odors associated with them,” whether those smells are “breath odors, body odors, urine odors, or stool,” Tamara Duker Freuman, a registered dietician in New York City, tells Allure. “In some cases, a particular body odor can give us insights about our health.”
Doctors are really only beginning to scratch the surface of what body odors can tell us, says Zeichner. For example, recent reports have detailed how “certain cancers of the skin thought to give off volatile organic compounds” have been detected by canines’ noses, he says. The same principle of using hyper-sensitive sniffing devices is also being applied to studying compounds in gasses that could be used to diagnose certain diseases, Freuman adds. If all you have is your own nose, though, and you’ve noticed that your B.O. is smelling off, how can you figure out what’s going on and what should you do about it? Here’s what the experts have to say.
Body odors are often caused by three things: diet, stress, and underlying medical conditions.
“Diet isn’t the only source of new or different body odors, though it’s never a bad place to start,” Freuman says. “These odors typically result from metabolic processes that produce volatile compounds (VOCs), which are molecules that evaporate, causing an odor in their wake.”
In some cases, the food-induced B.O. will show up in your sweat, Zeichner says, which happens when your body can’t properly break down certain compounds in your food. A common culprit of this is garlic, which contains sweat-polluting sulfur. The foods you eat can also obviously affect your breath: Onions, alcohol, fish are all likely to leave you in need of a mint.
Then there’s the “sweet and somewhat ‘fruity’ smell on the breath,” Freuman explains, which may be caused by the ketogenic diet. Reports on this connection are mixed, according to Niket Sonpal, an adjunct assistant professor of clinical medicine at Touro College of Osteopathic Medicine in New York City, although he acknowledges that theoretically, it’s possible.
If it’s not because of something you ate, your funk may have to do with relationship drama or an overloaded work schedule. “One of the number one reasons that body odor can increase, become a little bit more pungent, or have a more lingering scent, is stress,” says Sonpal.
Your body has two types of sweat glands, according to the Mayo Clinic: eccrine and apocrine. Eccrine glands are everywhere, producing the watery sweat that builds up when you’re working out. Apocrine glands, however, are concentrated in your armpits and groin and produce a different kind of fatty sweat. When your anxiety kicks up and the apocrine glands switch on, “that milieu of sweat from the gland in the armpit and the normal surface body bacteria make a smell,” Sonpal explains.
Finally, certain medical conditions can also cause strange smells, although these are pretty rare. “In general, these odors are caused by metabolic compounds, secreted in sweat, breath, or urine, that have a particular odor,” Nitin Kumar, a board-certified gastroenterologist in Effingham, Illinois, tells Allure. “Other times, the compounds do not have an odor but are metabolized by skin bacteria into compounds that do.”
Take “fish odor syndrome”: As Freuman explains, this rare genetic condition, which doctors call trimethylaminuria, leaves the body incapable of breaking down a pungent-smelling chemical compound found in fish, cruciferous veggies, and soy. This in turn “causes an all-over fish smell” in people who have the condition.
A person with phenylketonuria, another rare inherited disorder, can develop a particular scent when triggered by a type of artificial sweetener; the condition actually causes you to smell a bit like a mouse, says Kumar.
Other medical conditions like liver disease, diabetes, and kidney failure can also cause strange-smelling breath or sweat, Kumar says. Again, though, this is rare. “It’s likely that all of these diseases would be found due to other signs or symptoms first,” he explains. “But in rare cases, the odor may be noticed first.”
Prevention is the most effective way to address stink, but supplements could help.
For some stink situations, the fix is pretty straightforward: Avoid foods that leave you with an undesirable odor, focus on reducing your stress levels, or try a new deodorant. If you’re not willing to give up your garlic bread, you can try taking a soluble fiber or activated charcoal supplement right before eating it (or whatever food is leading to the stink), according to Freuman. These supplements “bind to VOCs in the gut and may reduce their odor-causing potential,” she says.
One word of caution: some studies have shown that activated charcoal can interfere with other organic molecules, like those in thyroid medication or birth control. You should make sure you talk to your doctor before taking any new supplements.