UNC Health Care
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What Your Bad Breath Might be Telling You

Halitosis—or persistent bad breath—can be awkward, embarrassing and even offensive. And it doesn’t discriminate. Everyone gets halitosis at some point, and doctors estimate that 20 to 30 percent of people in the U.S. have it at any given point.

While bad breath is usually just a nuisance in need of a minty fix, it can also be a sign of serious health issues. We spoke with Ram Neelagiri, MD, MPH, of UNC Primary and Specialty Care at Brier Creek to learn more.

Common Causes of Bad Breath

Halitosis is most often caused by poor oral hygiene, Dr. Neelagiri says. “If you don’t floss or brush your teeth properly, bacteria will break down the leftover food particles and produce an odorous sulfur compound. Likewise, water serves as an aid to wash away food and bacteria, so if you don’t drink enough water you could be left with an unpleasant smell.” Coffee can also cause bad breath by slowing down saliva production that is responsible for killing bacteria in your mouth and digesting food particles that cause bad smells.

Sinus issues such as sinus infections, postnasal drip and nasal polyps are also a common reason for halitosis because they facilitate the buildup of odor-causing bacteria in your nose and sinus cavities.

Serious Causes of Bad Breath

The good news is that most cases of halitosis are caused by poor oral hygiene and can be easily remedied. Dr. Neelagiri estimates that only about 5 to 10 percent of bad breath is caused by diseases outside of the mouth or nose. Still, it’s important to be aware that bad breath may point to a number of serious issues.

  • Diabetes
    Diabetes occurs when your body lacks insulin, the hormone responsible for bringing glucose to your cells to be used for energy. When this happens, the body will turn to burning fat instead of sugar which produces ketones in your body. One ketone in particular, acetone, will cause your breath to smell like nail polish. People who eat an extreme low-carb diet such as the ketogenic diet or the Atkins diet may also experience bad breath, as the fat burning associated with these diets also releases ketones.
  • Kidney Disease
    The kidneys are the bean-shaped organs below your ribs that are responsible for filtering the blood to be used by your heart and body. If your kidneys fail, they can’t properly filter minerals out of your bloodstream. If there is a mineral buildup in your bloodstream, you’ll be left with a metallic taste in your mouth and your breath will smell like ammonia.
  • Liver Disease
    Your liver regulates your body’s blood sugar. If your liver can’t function properly, toxins will build up in your bloodstream and give you foul-smelling breath that takes on a sweet, musty odor.
  • Pneumonia
    Pneumonia is a bacterial or viral infection in your lungs. When the lungs become infected, the air sacs become inflamed and fill up with phlegm or pus. This causes serious fits of coughing, and when the odorous phlegm or pus is coughed up, it will cause halitosis.
  • Bronchitis
    Bronchitis occurs when your bronchial tubes, the tubes responsible for carrying air to your lungs, get infected and swollen. This causes a severe cough that is accompanied by foul-smelling mucus and bad breath.
  • GERD
    Gastroesophageal reflux disease (GERD) occurs when acid in the stomach flows back up the esophagus, the tube that connects your mouth and stomach. GERD is often associated with chest pain, the feeling of a lump in your throat and the regurgitation of undigested food that can cause bad breath.

When Should You See a Doctor?

Dr. Neelagiri emphasizes that while bad breath may be a sign of something more serious, most of the time it’s not. “Before visiting a doctor, make sure you brush your teeth regularly, and try to drink more water and gargle with wash. If it doesn’t go away, then come in and get it checked out. If you think the bad breath may be caused by something more serious, pay attention to your body. There will be other noticeable symptoms that indicate something is wrong.”


Concerned about bad breath? Find a doctor near you.