Bad Breath

Medically Reviewed By William C. Lloyd III, MD, FACS
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What is bad breath?

Bad breath (also called halitosis) is a common symptom of poor oral hygiene, sinus infection, eating certain foods, using tobacco products, or even dry mouth. The medical term for bad breath is halitosis. Bad breath results from sulfur compounds released by bacteria in the mouth, food odors, or salivary gland dysfunction.

Ninety percent of all bad breath originates in the mouth and airway passages. Poor oral hygiene is a common cause of chronic bad breath. Without brushing and flossing daily, food particles remain in the mouth, tongue, and between the teeth. These food particles collect bacteria, causing bad breath. Infections of the gums (gingivitis) and salivary glands can both result in bad breath. Other common causes include dry mouth and smoking or chewing tobacco.

Certain medical disorders can cause bad breath, such as post-nasal drip, tonsillitis, sinusitis and bronchitis. Gastrointestinal disorders may result in breath that smells like feces; this may indicate gastric reflux (GERD) or a bowel obstruction. Breath with a fruity odor may be a sign of diabetic ketoacidosis, a potentially life-threatening condition. Liver failure may be indicated if breath has an ammonia-like odor.

Bad breath alone is rarely a result of a serious problem. However, you should seek immediate medical care (call 911) if you experience bad breath along with other serious symptoms, such as high fever (higher than 101 degrees Fahrenheit), difficulty breathing, or prolonged vomiting.

If your bad breath is persistent or causes you concern, seek prompt medical care.

What other symptoms might occur with bad breath?

Bad breath may accompany other symptoms, which vary depending on the underlying disease, disorder or condition.

Oral symptoms that may occur along with bad breath

Bad breath may accompany other symptoms affecting the mouth including:

  • Bleeding gums

  • Bright red or red-purple appearance to gums

  • Dry mouth

  • Gum tenderness

  • Mouth or facial pain, especially when eating

  • Mouth sores

  • Receding gums

  • Redness over the side of the face or the upper neck

  • Sores that contain pus

  • Sore throat

  • Swollen gums

  • Swollen tonsils

Other symptoms that may occur along with bad breath

Bad breath may accompany symptoms related to the respiratory system and other body systems including:

  • Fatigue

  • Fever

  • Headaches

  • Pain, tenderness, swelling and pressure around the eyes, cheeks, nose or forehead

  • Postnasal drip

  • Sore throat

  • Stuffy nose or nasal congestion

Gastrointestinal system symptoms that may occur along with bad breath

Bad breath may accompany symptoms related to the gastrointestinal system including:

  • Abdominal gas or bloating

  • Abdominal pain (Zenker’s diverticulum)

  • Indigestion

  • Heartburn, or gastroesophageal reflux disease (GERD)

  • Nausea with or without vomiting

Diabetes symptoms that may occur along with bad breath

Bad breath may accompany symptoms related to diabetic ketoacidosis including:

Liver symptoms that may occur along with bad breath

Bad breath may accompany symptoms related to liver failure including:

Serious symptoms that might indicate a life-threatening condition

In some cases, bad breath may be a symptom of a life-threatening condition that should be evaluated immediately in an emergency setting. Seek immediate medical care (call 911) if you, or someone you are with, have any of these life-threatening symptoms including:

  • Breath that smells like feces

  • Difficulty thinking clearly

  • High fever (higher than 101 degrees Fahrenheit)

  • Prolonged vomiting

  • Rapid breathing (tachypnea) or shortness of breath

What causes bad breath?

Bad breath results from the action of bacteria that cause the breakdown of food particles in your mouth. Eating foods, such as onions and garlic, are a common source of bad breath. Chemicals from these foods are absorbed into the bloodstream, carried to your lungs, and exhaled.

Infections of the mouth and gums can cause bad breath and are often associated with poor oral hygiene. If the mouth and teeth are not cleaned daily, plaque forms on the teeth, irritates your gums (gingivitis), and may result in tooth decay.

Dry mouth is a common source of bad breath, occurring at night from mouth breathing and decreased saliva. Saliva cleanses the mouth and removes foreign particles. Medications and tobacco use, both of which cause dry mouth, may lead to bad breath. Bad breath also results from infections in the upper respiratory tract, including sinusitis, pharyngitis, laryngitis, and postnasal drip.

Other cases of bad breath are the result of underlying diseases. Some cancers and metabolic disorders cause a distinctive breath odor as a result of chemicals they produce. Diabetic ketoacidosis and liver failure can lead to unusual and distinctive changes in breath. Chronic reflux of stomach acids (gastroesophageal reflux disease, or GERD) has additionally been associated with bad breath.

Food or substance causes of bad breath

Bad breath may be caused by foods and substances including:

  • Garlic
  • Onions
  • Spices
  • Tobacco

Dental causes of bad breath

Bad breath can also be caused by dental conditions including:

  • Gingivitis (infection of the gums)
  • Periodontitis (infection of the gum line involving the teeth and bones)
  • Poor dental hygiene
  • Reduced saliva
  • Tooth decay
  • Unclean or poorly-fitting dentures

Disease causes of bad breath

Some diseases and conditions may be associated with bad breath including:

Serious or life-threatening causes of bad breath

In some cases, bad breath may be a symptom of a serious or life-threatening condition that should be evaluated immediately in an emergency setting. These include:

Questions for diagnosing the cause of bad breath

To diagnose your condition, your doctor or licensed health care practitioner will ask you several questions related to your bad breath including:

  • How long have you had bad breath?
  • Do you have diabetes?
  • Do you have any other symptoms?
  • What medications are you taking?
  • How often do you brush and floss your teeth?

What are the potential complications of bad breath?

If not properly treated, some infections and diseases resulting in bad breath can lead to serious complications including:

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2021 Jan 10
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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