Do you suddenly have really bad B.O.? Here's what might be going on.

A woman wearing a towel smells her underarm.
Can bad body odor be a sign of a health problem? (Getty Images)

Worrying that you have started to smell — and that others can tell — is agonizing on its own, and wondering if your health might be causing the odor only adds to the stress. Assuming you’re not on a shower strike or trying out a new deodorant that isn’t cutting it, what could be the culprit? According to experts, there are a few reasons why you suddenly have worse body odor.

All about body odor

To figure out what may be causing your potent body odor, it’s essential to understand precisely why we have it in the first place. Body odor (or bromhidrosis, if you’re being technical) is “caused by bacteria on the skin, which break down sweat, giving off a foul odor,” according to Dr. Joshua Zeichner, a dermatologist in New York City. This bacteria “lives on everyone and is considered to be part of our skin’s natural microbiome,” he notes.

Not all sweat is created equal, however, because not all sweat has that foul-smell-creating bacteria. There are two types of sweat glands in our body: eccrine and apocrine. That watery sweat you see after, say, an intense spin class is from your eccrine glands, which are found all over your body. The sweat from your eccrine glands doesn’t produce a smell.

Apocrine glands, on the other hand, are found in your armpits and genital area, as well as in the breasts and, interestingly, in the ears. “When sweat is produced within these glands, the odor is related not to the sweat itself but the breakdown of proteins within the sweat by bacteria,” Dr. Susan Massick, a dermatologist for the Ohio State University Wexner Medical Center, tells Yahoo Life. Apocrine glands begin to produce the chemicals that cause this smell after puberty, which is why you may notice that your teen is in need of deodorant suddenly.

There are some people who simply have more apocrine glands than others, says Massick, meaning that, unfortunately, they tend to be smellier — or have to work harder in order to avoid body odor. However, if you just noticed this foul smell, it’s likely you’re not one of these folks, as this is a genetic condition.

Do you have your personal hygiene covered?

Lifestyle changes can have a big impact on body odor. It may sound obvious, but both Massick and Zeichner say that personal hygiene is very important when it comes to avoiding overall smelliness. If you’ve been going to the gym and then skipping the shower, well — there’s your answer.

While he recommends regular bathing, you don’t always need to wash every inch of your body, Zeichner says. “A full body shower is not always necessary,” he says. “However, it is important to wash dirty areas like the face, underarms, under the breasts and genitals daily. I also always recommend bathing after heavy sweating — whether it’s from a warm day or working out.”

Massick says you can also “minimize sweating by staying cool, avoid overheating and wear loose-fitting, comfortable clothing that wicks away moisture.” Deodorant will also help mask the smell in your armpits, which is different from antiperspirants, which only address sweat. Massick recommends hypoallergenic brands that won’t irritate your skin.

How diet impacts body odor

Let’s say you have the personal hygiene stuff all sorted out — what else might be causing your body odor? Diet can be a major factor. According to Cleveland Clinic, your personal scent may be affected by certain foods, such as:

  • Cruciferous vegetables like broccoli, cabbage and kale.

  • Garlic.

  • Onions.

  • Spices like cumin, cayenne and paprika.

  • Red meat.

  • Alcohol.

Massick adds that “high protein or keto diets can also be a culprit” behind worsening body odor. The keto diet has been found to make breath and urine smell like nail polish remover. This is due to the process of converting fatty acids into chemicals called ketones, one of which is acetone — the same ingredient in most nail polish removers. Anecdotally, some people have found that the keto diet has seemingly changed the smell of the vagina as well, with some experts speculating that the diet may throw off the vagina’s pH balance.

How stress impacts body odor

If you’ve noticed yourself smelling lately, it’s also important to ask: Am I under more stress than usual? “Apocrine glands are typically activated from stress,” says Zeichner. “Stress sweat is a real condition, and in some cases may smell differently than regular sweat because of the different composition of the sweat from these glands.”

Medical conditions that may cause body odor

If you’ve ruled out the above, it’s possible the odor is caused by something medical. Zeichner says that fungus on the skin, such as severe cases of athlete’s foot, can lead to a foul smell. Other conditions that may trigger foul-smelling body odor, according to Massick, include:

  • Obesity.

  • Liver disease.

  • Thyroid disease.

  • Kidney disease, which can lead to an ammonia odor.

  • Diabetic ketoacidosis, which can lead to a fruity smell.

  • Hormonal fluctuations, as well as pregnancy and menopause.

  • Trimethylaminuria, a rare metabolic disorder related to enzyme deficiency that causes a fishy odor.

  • Taking certain medications, such as antidepressants.

If you’re concerned, you should see your general practitioner, who can run tests to find out if your body odor may be caused by any of the above. In general, though, if you’re showering regularly and using deodorant — and loved ones haven’t mentioned anything about your odor — there’s a good chance you may be more worried about it than other people are.

Got a health question? Email [email protected] and your query could be tackled in a future article.