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Halitosis - Bad Breath

Last Updated: Mar 1, 2019


Halitosis is an offensive odor also known as bad breath. This common problem affects approximately one-third of the population.

In 90% of individuals with halitosis, the underlying problem lies within the mouth and the condition is termed intraoral halitosis. Intraoral halitosis is primarily caused by oral bacteria, which produce foul smelling gases called volatile sulfur compounds (VSCs).

The other 10% of cases are classified as extraoral halitosis because the underlying problem is outside of the mouth. Uncontrolled medical diseases or adverse effects of medications are the most common causes of extraoral halitosis.


human mouth

Intraoral halitosis is frequently caused by the following conditions:

  • Gingivitis (gum inflammation) and periodontitis (gum disease). Gingivitis and periodontitis are caused by accumulations of bacteria on the teeth (dental plaque) and within pockets between the teeth and gums. These bacteria produce exceedingly high levels of foul smelling VSCs. Poor dental hygiene and smoking are known to increase the risk for gum disease.
  • Tongue coating. Accumulation of food and bacteria on the dorsal surface of the tongue produces significant odors.
  • Dental cavities. Tooth decay and associated infections commonly contribute to halitosis.
  • Food. When teeth are improperly brushed and flossed, bacteria adhere to food particles retained between the teeth and produce offensive odors. Additionally, some foods like garlic and onions temporarily cause bad breath.
  • Dry mouth (xerostomia). An inadequate amount of saliva makes clearing food particles more difficult.

Extraoral halitosis is commonly caused by the following disorders:

  • Liver failure
  • Diabetes mellitus
  • Kidney failure
  • Tonsil infections (tonsillitis)
  • Nasal cavity and sinus infections (sinusitis)
  • Nasal obstruction, resulting in mouth breathing and dry mouth
  • Certain cancers
  • Lung diseases
  • Gastroesophageal reflux, in which stomach acids abnormally flow back up to the esophagus and throat
  • Stomach infections (gastritis) or ulcers
  • Certain medications and medical problems that reduce the flow of saliva, thus promoting halitosis
  • Pseudo-halitosis, a psychological disorder in which individuals believe they have bad breath although no odor is present.


The symptoms of halitosis vary among individuals, and the extent of the condition ranges from mild to severe. Interestingly, many people with bad breath are completely unaware of their problem.

Diagnosis and Treatment

To evaluate halitosis, a clinician will subjectively judge a patient’s breath odor. This assessment, called an organoleptic measurement, involves sniffing the patient’s breath as it is exhaled and subjectively rating the severity of the odor.

Gas chromatography (GC) is a test that specifically measures exhaled VSCs, the most common cause of halitosis.

Sinuses shown in a lateral view

When genuine halitosis is detected, patients typically require an examination by a dentist as well as a physician to determine whether the odor is caused by an oral problem, or underlying medical condition, or both. Sometimes, if tonsillitis or sinusitis is suspected, an ear nose and throat specialist is indicated.

Treatment is directed at correcting the underlying causes of halitosis. The most effective interventions are as follows:

  • Brushing teeth twice daily
  • Brushing or scraping the dorsum of the tongue twice daily to reduce the amount of bacteria on the tongue surface
  • Flossing daily
  • Professional dental cleaning and treatment of gum disease
  • Antibacterial mouth wash to reduce some of the bacteria in the mouth (often merely masks odors for a few hours without correcting the underlying problem)
  • Lozenges and chewing gum to increase saliva
  • Artificial saliva or medications to treat dry mouth
  • Proper treatment of uncontrolled medical conditions
  • Special psychiatric assessment and counseling for individuals with pseudo-halitosis.


Most cases of halitosis are prevented with the practice of good oral hygiene, including teeth brushing, flossing, tongue cleaning, and abstinence from smoking. A dental examination and professional cleaning are recommended once or twice each year. Additionally, individuals should obtain proper medical care and treatment for any underlying diseases.


  • Seemann R, Conceicao MD, Filippi A, et al. Halitosis management by the general dental practitioner—results of an international consensus workshop. J. Breath Res. 2014 Mar;8(1):017101. doi: 10.1088/1752-7155/8/1/017101. Epub 2014 Feb 24.
  • Veeresha KL, Bansal M, Bansal V. Halitosis: A frequently ignored social condition. J Int Soc Prev Community Dent. 2011 Jan-Jun; 1(1): 9-13.
  • Campisi G, Musciotto A, Di Fede O, Di Marco V, Craxì A. Halitosis: could it be more than mere bad breath? Intern Emerg Med. 2011 Aug;6(4):315-9. doi: 10.1007/s11739-010-0492-4. Epub 2010 Dec 8.
  • Bad Breath. Mayo Clinic website. Accessed October 23, 2014.

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Tina Shahian, PhD

Tina is a writer for Innerbody Research, where she has written a large body of informative guides about health conditions.


A communication specialist in life science and biotech subjects, Tina’s successful career is rooted in her ability to convey complex scientific topics to diverse audiences. Tina earned her PhD in Biochemistry from the University of California, San Francisco and her BS degree in Cell Biology from U.C. Davis. Tina Shahian’s Linkedin profile.


In her spare time, Tina enjoys drawing science-related cartoons.