Possible Causes of Bad Breath or Halitosis

Halitosis — known as bad breath to most — is an embarrassing condition that can affect anyone at any time, and is caused by several factors. The most common causes of bad breath are preventable and easily treated, however certain medical conditions may also cause bad breath. Chronic halitosis may indicate an underlying medical concern that should be addressed by your dentist or medical doctor.

Learn about the most common reasons why you may experience bad breath, and when you should see a dentist for your halitosis.

The Food We Eat and Digestion

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The food we eat can adversely affect our breath. Odors from garlic, onions, cabbage, and certain spices may result in halitosis when the suspected food is absorbed into the bloodstream after digestion. When the blood has transferred to the lungs, the smell of the food is evident when you exhale.

With eating comes digestion, another cause of bad breath. Gasses produced during the digestive process may escape through your mouth, emanating the odor it produces. Poor digestion resulting in constipation and disorders of the bowel may contribute to bad breath again, from the gasses that are produced during this process.

Infrequent Brushing and Flossing

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It may seem like an obvious factor, but when you examine how limited and neglected brushing and flossing habits contributes to bad breath, the cause hits you like a brick wall — decaying food particles and bacteria trapped in your mouth.

When the food we eat is left behind either because it is trapped in hard to reach places such as the wisdom teeth, the tiny hair-like follicles on the tongue, or simply because brushing and flossing is neglected, it begins to decay in your mouth. The human mouth is 98.6 F, an ideal temperature for food to begin to decompose. When you exhale, the odor from the decomposing food, bacteria, and plaque causes the offensive odor.

Oral Diseases and Infections

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Periodontal disease is directly related to improper or neglected brushing and flossing. One major sign of this potentially irreversible oral disease is halitosis. The accumulation of plaque, bacteria, and decomposing food particles contribute to bad breath as they destroy the delicate tissue that surrounds our teeth.

The same bacteria that cause gum disease, tooth decay, and abscessed teeth are also responsible for halitosis.

Dry Mouth

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Xerostomia is a condition that causes a decrease in the production of saliva, resulting in a dry mouth. Several factors cause xerostomia, some of which may need to be treated by your doctor.

Saliva is necessary to provide lubrication the mouth to allow for proper chewing and swallowing. Saliva naturally cleanses the mouth and helps prevent cavities. If you are experiencing dry mouth, bad breath may occur because the food particles remain trapped in the mouth to rot and cause the unpleasant smell when you exhale.

Cause: Cigarette Smoking


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The effects of smoking on our overall health and wellness are frightening. Over 4,000 chemicals have been identified in cigarettes, 200 of which are poisonous. Lung cancer and COPD are obvious diseases that come to mind when you consider the health risk associated with the habit. But did you know smoking is also a major cause of periodontal disease? How does this relate to halitosis you ask? The smoke produced from a cigarette is inhaled into the lungs and then exhaled through the nose and mouth. This causes an immediate effect on your breath because the chemicals and residue from the smoke remain in your mouth and airways. Continued use of cigarettes contributes to gum disease, a major cause of bad breath.

Medical Conditions

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Unexplained or chronic bad breath may be an indication of an underlying medical condition or disease.

Ketoacidosis occurs in diabetics when there is insufficient glucose in the blood for the body to use as energy. An obvious sign of this is a fruity-smelling odor in the breath. People with eating disorders may experience halitosis, as well as frequent dieters. Breath that has a fishy smell or is reminiscent of urine or ammonia may be obvious in people with chronic kidney failure. After prolonged vomiting or if an obstruction is in the bowel, the breath may smell like feces. Sinusitis and lung infections also cause bad breath. Children with a foreign body trapped in their nose may experience halitosis. If suspected, see your doctor.

Treating and Preventing Bad Breath

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In order to treat your bad breath, the root cause of halitosis needs to be identified. Visit your dentist if you experience chronic bad breath (in other words bad breath that never goes away).

Over-the-counter breath fresheners such as gum, mints, breath strips, breath sprays, and certain mouth rinses will only provide a temporary relief from bad breath. These general guidelines will assist you in managing, and hopefully eliminate, your experience with bad breath.

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  • American Dental Association News Update "What Causes Bad Breath?"

  • A.D.A.M. Illustrated Health Encyclopaedia "Breath Odor"
  • A.D.A.M. Illustrated Health Encyclopaedia "Chronic Renal Failure"
  • A.D.A.M. Illustrated Health Encyclopaedia "Diabetic Ketoacidosis"
  • A.D.A.M. Illustrated Health Encyclopaedia "Sinusitis"
  • National Institute of Dental and Craniofacial Research (NIDCR)- "Dry Mouth"