Halitosis – Causes, Signs and symptoms


Also called: Oral Malodor, Bad Breath

Reviewed By:
Andrew M. Sicklick, D.D.S.


Halitosis (bad breath) is a condition that typically originates in the mouth. It is most often caused by the combination of bacteria, food particles and dead cells that can accumulate in the mouth. Poor dental hygiene and a lack of saliva, which helps to wash away germs, often contribute to the problem.

The primary sign of halitosis is a detectable unpleasant odor when a person exhales or speaks. Additional signs may also occur, depending on the cause of the halitosis. For example, swollen gums or tartar on the teeth may indicate tooth decay or gum disease. A stuffy nose, sore throat and coughing may indicate halitosis as a result of a respiratory tract infection. Certain smells can indicate specific disorders. For instance, a “fruity” smell may indicate uncontrolled diabetes and an ammonia-like smell may indicate kidney disease. Halitosis can also be a temporary condition caused by eating certain foods or beverages (e.g., garlic, coffee).

Halitosis can be diagnosed by smell. Additionally, a dentist or physician may collect a patient’s medical history to help identify potential causes of the odor. For some types of oral causes (e.g., some cases of gum disease), a periodontist may be recommended. If non-oral causes are suspected, a patient may be referred for additional testing.

There are a wide variety of over-the-counter products (e.g., mints, sprays, scented toothpastes) designed to treat halitosis. However, these only provide temporary relief by masking the mouth odor. Successful treatment of halitosis depends on identifying and treating its cause. In most cases, this involves getting appropriate dental treatment.

Halitosis can be prevented in a number of ways, including proper dental hygiene (brushing, flossing), eliminating foods or beverages that trigger bad breath and drinking plenty of water. These methods can also help reduce and eliminate symptoms in existing cases of halitosis.

About halitosis

Halitosis is the medical term for bad breath. It can occur when decaying matter (e.g., food particles, dead cells) accumulates in the mouth and combines with bacteria to produce an unpleasant odor. Bacteria thrive in warm and moist areas such as the mouth, especially on the rough surface of the tongue. When large amounts of decaying matter exist, the bacteria normally present in the mouth consume it and expel foul-smelling by-products.

In addition, nasal discharge or mucus can accumulate at the back of the throat, fostering the growth of bacteria and producing an unpleasant odor noticeable in a person’s breath.

Certain foods (e.g., garlic, onions) and beverages (e.g., coffee, alcohol) can produce a distinctive breath odor. After digestion, molecular components of these products are carried by the bloodstream to the lungs, where their odor is released with breath as a person exhales. This continues until the food or drink has been completely eliminated from the body or it can be reduced by brushing the teeth.

Halitosis is fairly common and most people experience it at some point. For example, bad breath that occurs upon waking in the morning (morning breath) is caused by a decrease of saliva in the mouth during sleep. Saliva helps to keep the mouth moist and rid it of decaying food particles, bacteria and dead cells that can accumulate there.

In most cases, halitosis is temporary – it is resolved when saliva production is restored, when certain foods or beverages exit the body, or when halitosis caused by poor dental hygiene is professionally treated. Halitosis can also be chronic. The causes of chronic halitosis are numerous. They range from chronic infections (e.g., sinusitis) to underlying medical conditions (e.g., uncontrolled diabetes, lung disease, kidney disease). It is estimated that 90 million people have chronic halitosis, according to the Academy of General Dentistry.

When a person believes he or she has halitosis, but the odor cannot be detected by anyone else, it may be a case of pseudohalitosis, which may indicate a psychological problem.

Potential causes of halitosis

Most often, halitosis (bad breath) is caused by bacteria in the mouth. These bacteria create a foul odor in response to the presence of food particles or other debris in the mouth. Poor dental hygiene and a lack of saliva exacerbate the problem.

Common causes of halitosis include:

  • Oral infections. The significant bacterial buildup that occurs with oral infections such as tooth decay, tooth abscess and gum disease cause halitosis.
  • Dry mouth (xerostomia). A lack of saliva causes an abnormal dryness in the mouth and may allow the buildup of food particles and dead cells in the mouth. This can lead to halitosis. Dry mouth can occur as a side effect of certain medications, medical conditions, radiation therapy for cancer treatment or breathing through the mouth instead of the nose. Alcohol and alcohol-based mouth rinses  can also contribute to drying out the mouth.

  • External agents. These may include certain foods or beverages (e.g., garlic, onions, cabbage, coffee, alcohol) and certain activities (e.g., chewing or smoking tobacco). Tobacco use can also cause dry mouth and gum disease, increasing the likelihood of halitosis among tobacco users. Oral appliances (e.g., dentures, retainer, mouth guard) can also harbor odor-causing bacteria and food particles, causing halitosis.

  • Certain diets. Consuming few or no carbohydrates (sugars and starches used as energy by the body) can cause ketoacidosis (in which the body burns fat instead of carbohydrates for energy and releases odor-causing waste products in the breath), producing breath with a “fruity” or sweet smell. This can also occur during periods of fasting.

Non-oral causes of halitosis are less common. These can include:

  • Respiratory tract infections. These may include throat, sinus or lung infections. Increased mucus levels that result from these infections can increase the number of odor-causing bacteria in the body and produce halitosis. For example, colds, sinus infections and many other upper respiratory infections cause post-nasal drip. Post-nasal drip allows bacteria to build up on the back of the tongue, resulting in bad breath.

  • Digestive problems. A variety of conditions involving the digestive system can cause halitosis, including gastroesophageal reflux disorder (GERD) and bowel obstruction.

  • Diabetes. Condition in which the body is unable to properly process sugar (glucose) in the blood. Uncontrolled diabetes can result in “fruity” smelling breath.

  • Kidney disease. Conditions affecting the kidneys (which filter waste from the blood) can cause halitosis. When the kidneys fail to work properly, an ammonia-like odor can be produced in the breath.

  • Nasal obstruction. When an airway passage in the nose becomes blocked, nasal discharge at the back of the throat can lead to halitosis. This occurs more often among children, due to foreign objects being lodged in the nose.

Signs and symptoms of halitosis

The primary sign of halitosis (bad breath) is a foul odor emanating from a person’s mouth upon exhaling or when talking. This odor can have a distinctive smell, depending on its cause. For example, sweet or “fruity” smelling breath may indicate diabetes. Breath that smells like feces may indicate a bowel obstruction, and breath that smells like ammonia or urine may indicate kidney failure.

People with halitosis may or may not be able to detect the unpleasant odor themselves. Anyone who has become accustomed to a certain body odor may no longer notice it or may not view it as unpleasant. In such cases, people with halitosis may discover the condition based upon the reactions of others (e.g., stepping away from a person with halitosis when that person is speaking). In addition, other people may inform a person with halitosis that they have bad breath. 

Additional signs and symptoms may appear with halitosis, which can indicate a dental problem or medical illness. These may include:

  • Food particles, plaque or tartar on the teeth
  • Tooth decay
  • Swollen gums
  • Drainage from the mouth
  • Open sores inside the mouth
  • Dry mouth
  • Bad taste in the mouth
  • Cold or flu-like symptoms (e.g., sore throat, fever)
  • Signs of an underlying medical condition (e.g., heartburn due to acid reflux, vomiting due to a bowel obstruction)

Patients should consult their dentist or physician if their halitosis is accompanied by signs of a tooth or gum condition (e.g., tooth decay, swollen gums), or if halitosis continues despite a proper diet and dental care. A physician should be contacted for halitosis with signs of infection or other medical illness (e.g., diabetes, kidney disease).

Diagnosis methods for halitosis

A dentist or physician can usually identify halitosis (bad breath) by smelling a patient’s breath. An examination of the teeth and gums is usually conducted to identify or rule out an oral cause of the halitosis. If gum disease is suspected to be the cause of a patient’s halitosis, consultation with a periodontist may be recommended.

A physical examination, including feeling the head or neck, may be conducted to identify any signs of infection, which may be causing the halitosis. A medical history may be taken in order to identify other possible causes of the problem. A patient may be asked about when symptoms began, current medications, diet and tobacco use.

Sometimes a potential cause may be identified based on how the breath smells (e.g., a “fruity” smell may indicate diabetes). If a non-oral cause is suspected, patients may be referred for additional testing. These tests may include blood tests, urine tests and x-rays of the chest or sinuses.

Treatment and prevention of halitosis

Successful treatment of halitosis (bad breath) will depend on identifying and treating its cause. In most cases of halitosis, this means receiving the appropriate dental treatment. For example, any existing tooth decay, abscesses or gum disease needs to be treated in order to have an effect on a patient’s breath odor. 

There are many over-the-counter remedies that claim to treat halitosis (e.g., sprays, mints, gum, mouthwashes, scented toothpastes). However, rather than treat bad breath, these products merely mask it. Their effects are usually temporary, at best, and do not treat the underlying problem.

Additional methods to treat and prevent halitosis include:

  • Regular visits to the dentist. Periodic teeth cleanings and dental examinations can help prevent problems that can cause halitosis. Regular examinations can reveal oral infections (e.g., tooth decay) that are the source of halitosis.

  • Proper dental hygiene. This helps to keep the mouth free of food particles and dead cells that can lead to halitosis. Daily dental hygiene consists of:

    • Brushing the teeth, tongue and gums. This should be done upon waking in the morning, at bedtime and after meals to remove decaying matter and bacteria from areas where they can accumulate. The tongue can be brushed lightly (about five to 15 strokes) with a soft-bristled toothbrush or special tongue scraper. The inner cheeks and roof of the mouth may also be brushed.

    • Flossing. This removes food particles, plaque and bacteria that become lodged between the teeth.

    • Special mouth rinses. Antimicrobial mouth rinses can help control plaque, and fluoride mouth rinses can help prevent tooth decay that can lead to halitosis.

  • Plaque prevention alternatives. These help prevent the buildup of bacteria in the mouth when a person is unable to perform proper dental hygiene, and include eating foods such as:

    • Apples
    • Parsley or mint leaves
    • Raw carrots
    • Raw celery

  • Encourage saliva production. Chewing sugar-free gum and sucking on sugar-free candy or lozenges can stimulate saliva production. Saliva helps to rid the mouth of odorous germs and helps prevent dry mouth, which can cause halitosis. Artificial saliva may be prescribed by a dentist in some cases.

  • Drink plenty of water. This helps wash away germs, as well as encourage saliva production. It may also help dilute concentrations of the smelly waste products released in the breath of people who skip meals, consume too few carbohydrates or have diabetes.

  • Keep oral appliances clean. Daily cleaning of all oral equipment (e.g., dentures, retainer, mouth guard) can prevent the buildup of bacteria and/or food particles on these devices, which can lead to halitosis.

  • Periodically replace toothbrush. A new toothbrush should be used every few months to reduce bacterial buildup on brushes that can lead to halitosis.

  • Avoid triggers. Eliminating foods or beverages that may be responsible for halitosis (e.g., garlic, onions, coffee, alcohol) can prevent it. This may also include tobacco products.

When halitosis is a symptom of an underlying medical condition (e.g., diabetes, kidney failure) the condition will need to be treated in order to eliminate the halitosis. Long-term care is usually required.

Questions for your doctor regarding halitosis

Preparing questions in advance can help patients have more meaningful discussions with their physicians or dentists regarding their conditions. Patients may wish to ask their dentist the following questions related to halitosis (bad breath):

  1. I experience bad breath every day. Is this normal?
  2. How can I tell if halitosis is the result of something I ate, or if it’s something more serious than that?
  3. Does halitosis indicate that I have an oral or medical problem?
  4. What do you think is causing my halitosis?
  5. Should I see a specialist to determine the cause of halitosis?
  6. What types of tests will I undergo? How should I prepare for them?
  7. How should I treat my halitosis?
  8. Is there a particular type of sugar-free gum or candy you recommend for me to stimulate saliva production and help prevent halitosis?
  9. Do you recommend that I brush my tongue, cheeks and roof my mouth? How often? Do I need special equipment to do this?
  10. What changes in my condition should I report to you?
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