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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:

Extraoral halitosis is commonly caused by the following disorders:


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:


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.


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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.