Product Reviews
Updated on January 6, 2023
6 min read

Common Causes of Bad Breath & Treatment Options

NewMouth is reader supported. We may earn a commission if you purchase something using one of our links. Advertising Disclosure.

What is Halitosis (Bad Breath)?

Halitosis, the medical term for bad breath, affects about 40 million Americans in the United States.

Bad breath is characterized by an unpleasant and persistent odor in exhaled breath that is typically not serious. There are a variety of causes of bad breath that are linked to poor dental hygiene, eating habits, or even dehydration.

The tongue also harbors bacteria, and if it is not brushed daily, halitosis can develop. In some cases, if halitosis persists even after brushing, it may be a sign of an underlying infection or disease.

Halitosis also occurs less in vegetarians than meat-eaters. If the mouth is not cleaned properly, leftover meat particles will begin to decay and produce a foul smell.

Risk Factors & Causes of Halitosis

The cause of bad breath could be linked to lifestyle habits, diet, poor dental care, or an individual’s medical history. Common risk factors include:

Poor Oral Hygiene

Without correct and regular brushing and flossing, food remains in the mouth. This remaining food results in a breeding ground for bacteria. In addition, the food will rot and produce an unpleasant odor.

Mouth fresheners, gums, and sprays could help temporarily if used in between flossing, brushing, and rinsing with chlorine dioxide mouthwash.

Chewing parsley, basil, mint, or cilantro also helps control bad breath.


Coffee is a highly acidic substance that can lead to dry mouth, tooth discoloration, and halitosis. However, rinsing with mouthwash, brushing, and flossing after drinking coffee reduces bad breath.


Alcoholic drinks and mouthwashes containing more than 25 percent alcohol can lead to halitosis.

Sugar and Processed Foods

Naturally occurring bacteria in the mouth feeds on sugars and results in a sour smell. So, you should eat a balanced diet to counteract the effects of unhealthy foods on your oral health and breath.

Tobacco Products

Cigarettes, cigars, smokeless tobacco, and chewing tobacco stain the teeth and put the body at risk for a myriad of diseases, as well as cause bad breath.

Certain Medications

Blood pressure medications, such as beta-blockers, diuretics, alpha-blockers, and calcium channel blockers, can lead to halitosis. Antihistamines, tetracyclines, sulfa, antidepressants, and decongestants can also cause bad breath.

Dry Mouth

Dry mouth, also called xerostomia, is a non-life-threatening oral condition that occurs when the salivary glands in the mouth do not produce enough saliva to keep the mouth wet.

It is caused by insufficient fluid intake and certain prescription medications. Cancer treatments, such as chemo, can also result in thick saliva, causing dry mouth.

Xerostomia naturally occurs while you are sleeping and typically causes bad breath in the morning. In particular, adults who sleep with their mouths open are more likely to develop dry mouth.


Low-carb diets (ketosis), fasting, and high-protein diets can cause halitosis. This includes eating excessive amounts of eggs, dairy, and red meat. Not eating enough carbohydrates can also cause this condition.


Dehydration, mucus build-up, and tonsil infections can cause bad breath. Hormonal changes in women, especially during pregnancy, can result in bad breath as well.

Rare Causes of Bad Breath

The most common cause of bad breath is oral hygiene. However, other situations can also be to blame.

Rare causes of bad breath include:


When the insulin levels of someone with diabetes are very low, their bodies can no longer use sugar and use fat stores instead. When fat is broken down, ketones are made and build up. Ketones can be poisonous in large numbers and create a distinctive and unpleasant breath smell.

Bowel Obstruction

Breath can smell like feces if there has been an extended period of vomiting, especially if someone has a bowel obstruction.


This is a condition in which airways become wider than usual. This allows for a build-up of mucus, leading to bad breath.

Aspiration Pneumonia

This is a swelling or infection in the lungs or airways from inhaling vomit, saliva, food, or liquids, resulting in an unpleasant breath odor.


Breath smells can differ depending on the cause of the problem. It is best to ask someone close to check your mouth odor as it can be challenging to assess it yourself.

Look at the inside of your mouth to see if you notice a white coating on the back of your tongue, this is a common sign of bacteria that causes bad breath.

Some people worry about their breath even if they have little or no mouth odor. This condition is known as halitophobia, and it may lead to obsessive mouth-cleansing behavior.


A general dentist will often smell the breath of someone with suspected halitosis and rate it on a six-point intensity scale. The dentist may scrape the back of the tongue and check the scrapings for smell, as this area can typically be a source of the odor.

Several sophisticated detectors can rate the smell more accurately.

They include:

  • Halimeter: This picks up low levels of sulfur.
  • Gas chromatography: This test assesses three sulfur compounds, which are hydrogen sulfide, methyl mercaptan, and dimethyl sulfide.
  • BANA test: This measures levels of a certain enzyme created by halitosis-causing bacteria.
  • Beta-galactosidase test: This test checks levels of the enzyme beta-galactosidase, which is linked to bad mouth odor.

Treatment Options for Bad Breath

Halitosis typically goes away on its own with lifestyle changes and proper oral care. In particular, good oral care tips include:

Routine Dental Exams and Preventive Treatment

The American Dental Association (ADA) suggests that adults visit a dentist for regular exams and teeth cleanings at least twice a year (every six months).

During dental exams, a dentist or dental hygienist examines the mouth for cavities, decay, gum disease, and other oral health conditions.

Preventing Bad Breath

Brushing twice a day, flossing at least once a day, and rinsing the mouth with an alcohol-free mouthwash regularly kills bacteria and keeps the mouth healthy.

Brushing the tongue with a scraper also helps prevent bad breath.

If you wear dentures, be sure to take them out at night and clean them before putting them back in your mouth.

Keep your mouth moist by encouraging saliva flow. Eat healthy foods that make you chew. Carrots and apples require a lot of saliva.

You can also suck on sugar-free lozenges, or your dentist can prescribe lozenges to keep your mouth moist.

Other halitosis prevention techniques and treatment options include:

  • Brush your tongue, cheeks, and roof of your mouth. Most bad breath bacteria live on the tongue.
  • Chewing Sugarless Gum (stimulates bacteria-fighting saliva).
  • Avoiding Toothpicks (they damage the gums and teeth).
  • Using anti-VSC Oral Care Products (they do not contain alcohol or zinc).
  • Keep a food journal to see if certain foods are causing bad breath. Eliminate certain foods temporarily to see if your breath improves.
Last updated on January 6, 2023
6 Sources Cited
Last updated on January 6, 2023
All NewMouth content is medically reviewed and fact-checked by a licensed dentist or orthodontist to ensure the information is factual, current, and relevant.

We have strict sourcing guidelines and only cite from current scientific research, such as scholarly articles, dentistry textbooks, government agencies, and medical journals. This also includes information provided by the American Dental Association (ADA), the American Association of Orthodontics (AAO), and the American Academy of Pediatrics (AAP).
  1. Baiju, R M, et al. “Oral Health and Quality of Life: Current Concepts.” Journal of Clinical and Diagnostic Research : JCDR, JCDR Research and Publications (P) Limited, June 2017.
  2. Bicak, Damla Aksit. “A Current Approach to Halitosis and Oral Malodor- a Mini Review.” National Library of Medicine, The Open Dentistry Journal, 30 Apr. 2018.
  3. Kapoor, Uditi, et al. “Halitosis: Current Concepts on Etiology, Diagnosis and Management.” European Journal of Dentistry, Medknow Publications & Media Pvt Ltd, 2016.
  4. Kumbargere Nagraj, Sumanth, et al. “Interventions for Managing Halitosis.” The Cochrane Database of Systematic Reviews, John Wiley & Sons, Ltd, 11 Dec. 2019.
  5. Naseem, Sajida, et al. “Oral Hygiene Practices and Teeth Cleaning Techniques among Medical Students.” National Library of Medicine, Cureus, 18 July 2017.
  6. Tungare, S, et al. Halitosis. StatPearls Publishing, 2021.
linkedin facebook pinterest youtube rss twitter instagram facebook-blank rss-blank linkedin-blank pinterest youtube twitter instagram