Health Conditions

Smelling Sickness: Body Odor May Be Sign of Disease

BY National Institutes of Health TIMEAugust 30, 2022 PRINT

Did anyone ever tell you that you smell bad? Funky breath or stinky underarms can happen to anyone, at any age. Whether or not you’ve noticed them, some body odors can signal a health problem. But most breath and body odors are normal.

“Bad breath is most often caused by bacteria on the teeth and tongue,” explains Dr. Madeleine S. Deming, an internal medicine expert at the NIH Clinical Center.

It’s normal if your breath smells a little in the morning, especially if you slept with your mouth open. A dry mouth allows bacteria to thrive. Bacteria that live in the mouth can make compounds that have sulfur. These compounds are especially stinky. They can smell like rotten eggs or onion, for example.

If bad breath isn’t cleared up by brushing your teeth or using mouthwash, it may be a sign of another issue. Over time, bacteria can cause tooth decay and gum disease. Decay and gum disease do not smell good. Both require a trip to the dentist for treatment.

Other causes of foul breath odor may be sinus, throat, or lung infections. These need to be treated by a health care professional, too.

Your breath can also carry clues of disease from other parts of your body. That’s because you exhale more than just air. Your breath also contains gassy compounds that move from your organs through the bloodstream into your lungs.

Breath that smells fruity or like rotten apples, for example, can be a sign of diabetes that’s not under control.

Rarely, people can have bad breath because of organ failure. A person with kidney failure may have breath that smells like ammonia or urine. Serious liver disease can make breath smell musty or like garlic and rotten eggs.

Compounds that are transported through the blood can also be released through your sweat glands. That can make your armpits and skin smell bad. It’s normal for stress to cause smelly compounds to be released through your sweat.

But your armpits can smell for other reasons too. Both moisture and hair enable bacteria to thrive. These bacteria can make smelly compounds. Bathing, shaving, and deodorant can help keep these odors in check.

Because certain diseases cause breath or body odors, NIH-supported researchers are developing an electronic “nose” to help doctors detect them. This research is at an early stage. In the lab, scientists can already analyze odor compounds from the body. They’ve even trained dogs to detect signs of certain cancers in breath samples.

If you’re concerned about a new or worsening body odor, “a trip to the doctor for evaluation is always the first step,” Deming advises. “Bad breath is best assessed by a dentist.”

Your dentist can examine your mouth for signs of trouble. If body odor is your concern, your doctor can conduct a physical exam. If needed, your doctor can suggest further tests.

“A trial of avoiding foods that are known to cause body odor may be considered. In rare cases of body odor due to an underlying medical condition, the treatment of that condition may help to manage the odor as well,” Deming says.

Concerned About a Body Odor?

To prevent strong breath or body odor:

  • Bathe, wear clean clothes, and use deodorant.
  • Clean and care for your teeth and mouth.
  • Keep your mouth moist and your body dry.
  • Avoid eating onions, garlic, and other strong-smelling foods.


Human breath metabolomics using an optimized non-invasive exhaled breath condensate sampler. Zamuruyev KO, Aksenov AA, Pasamontes A, Brown JF, Pettit DR, Foutouhi S, Weimer BC, Schivo M, Kenyon NJ, Delplanque JP, Davis CE. J Breath Res. 2016 Dec 22;11(1):016001. doi: 10.1088/1752-7163/11/1/016001. PMID: 28004639.

Breath Testing for Barrett’s Esophagus Using Exhaled Volatile Organic Compound Profiling With an Electronic Nose Device. Chan DK, Zakko L, Visrodia KH, Leggett CL, Lutzke LS, Clemens MA, Allen JD, Anderson MA, Wang KK. Gastroenterology. 2017 Jan;152(1):24-26. doi: 10.1053/j.gastro.2016.11.001. Epub 2016 Nov 5. No abstract available. PMID: 27825962.


A part of the U.S. Department of Health and Human Services, NIH is the largest biomedical research agency in the world.
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