The Causes of Halitosis (Bad Breath)

Table of Contents
View All
Table of Contents

Social interactions are an important part of our day-to-day activities. These social interactions can be affected when you have bad breath or halitosis. This can be difficult for several reasons. You may not even know you have bad breath because of gradual tolerance to your own breath smell.

You may also experience problems with your sense of smell with some causes of bad breath. Making this problem even more difficult or distressing for you is that your family and friends may not be comfortable telling you that you have a problem.

Dentist examining senior female patient teeth
Luis Alvarez / Getty Images

Oral Causes of Bad Breath

You currently have about 500 different types of bacteria in your mouth. It is easy for these bacteria to multiply as the oral cavity is an ideal location for bacterial growth due to the average temperature of 37°C and a humidity level of 96%.

The most common places for bacteria to grow are on coated tongues and in the space between your gums and your teeth, known as the periodontal space. About 90% of all cases of bad breath originate inside the mouth itself. Most oral causes of bad breath are related to food debris and plaque that causes:

  • Caries (cavities)
  • Gingivitis
  • Periodontitis

One much less common cause of bad breath is oral cancer.

Medications (like phenytoin, cyclosporin, and calcium channel blockers) can cause your gums to enlarge and increase your risk for bad breath. The relationship of periodontal disease and bad breath is not well understood, but the two are strongly associated.

Saliva helps to keep the level of bacteria in the oral cavity within normal limits. This is your body's natural way of cleaning your mouth. Disorders can affect your production of saliva, leading to a dry mouth (xerostomia) including:

  • Diabetes
  • Sjogren's syndrome
  • Medications - antidepressants, antihypertensives (blood pressure), diuretics (water pills), and antipsychotics
  • Radiation therapy
  • Chemotherapy 

Other conditions that cause disease in your teeth can additionally cause symptoms of bad breath. Any kind of infection in your mouth (such as an abscessed tooth) is likely to cause a foul odor. You may need treatment with antibiotics or dental treatments depending on your specific problem.

Improving your oral hygiene by flossing, brushing, use of mouth wash as prescribed by your dentist can decrease your risk of having bad breath when it is related to oral causes.

If you have chronic dry mouth or gum disease from a medication you are taking you will need to talk to your healthcare provider about switching the medication or other ways to mitigate these side effects. For example, there are currently over-the-counter and prescription hygiene products specifically designed to combat dry mouth.

Non-Oral Causes of Bad Breath

Outside of the oral cavity, almost any body system (gastrointestinal, endocrine, blood, kidney, liver, etc.) can have specific disorders which make up 8% of the cases of bad breath. These causes can not be identified as easily, because the oral cavity itself does not have a malodorous smell. Disorders related to the ear, nose, and throat are some of the more common sources of bad breath outside of disorders of the mouth.

Respiratory causes of halitosis include bronchitis, bronchiectasis, and lung infections. Stomach disorders that cause bad breath include hiatal hernia, Zenker's diverticulum, and pyloric stenosis. Liver, kidney, and blood disorders can also cause symptoms of bad breath. If you are able to identify one of these causes for your bad breath you will need to work with a healthcare provider to manage the underlying medical disorder.

ENT-Related Causes of Bad Breath

Treatment of ENT-Related Bad Breath

Increasing oral hygiene in ENT-related bad breath will not resolve the problem. It may temporarily help mask the odor. However, unless the underlying cause is treated, the bad breath will not resolve.

For example, removing enlarged tonsils or clearing diseased tissue from the sinuses can decrease halitosis. Healthcare providers who specialize in these types of disorders are called otolaryngologists. 

Other treatments may include using antibiotics or allergy treatments to resolve sinusitis. Each specific ENT disorder will have its own unique treatment that, once used, will resolve any symptoms of bad breath.

9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Aylıkcı BU, Colak H. Halitosis: From diagnosis to managementJ Nat Sci Biol Med. 2013;4(1):14-23. doi:10.4103/0976-9668.107255

  2. Veeresha KL, Bansal M, Bansal V. Halitosis: A frequently ignored social conditionJ Int Soc Prev Community Dent. 2011;1(1):9-13. doi:10.4103/2231-0762.86374

  3. Cleveland Clinic. Bad breath (halitosis): Possible causes.

  4. American Academy of Oral Medicine. Gingival enlargement.

  5. López-Pintor RM, Casañas E, González-Serrano J, et al. Xerostomia, hyposalivation, and salivary flow in diabetes patientsJ Diabetes Res. 2016;2016:4372852. doi:10.1155/2016/4372852

  6. Pinna R, Campus G, Cumbo E, Mura I, Milia E. Xerostomia induced by radiotherapy: an overview of the physiopathology, clinical evidence, and management of the oral damageTher Clin Risk Manag. 2015;11:171-88. doi:10.2147/TCRM.S70652

  7. American Dental Association. Bad breath: Causes and tips for controlling it.

  8. Cleveland Clinic. Bad breath (halitosis): Care and treatment.

  9. Kapoor U, Sharma G, Juneja M, Nagpal A. Halitosis: Current concepts on etiology, diagnosis and managementEur J Dent. 2016;10(2):292-300. doi:10.4103/1305-7456.178294

Additional Reading

By Kristin Hayes, RN
Kristin Hayes, RN, is a registered nurse specializing in ear, nose, and throat disorders for both adults and children.