Bad breath (halitosis)

Everyone experiences bad breath at times, particularly in the morning. This is normal and can be eliminated with good oral and dental hygiene. Sometimes, however, diseases of the mouth cavity and nasopharynx or chronic liver and kidney diseases may be the reason for bad breath. If so, these diseases require treatment.

At a glance

  • Having bad breath is normal to a certain extent.
  • It usually occurs as a result of an inadequate flow of saliva or deposits of food particles between the teeth.
  • Alcohol, nicotine and certain types of food can also cause bad breath.
  • In some cases, halitosis may be a symptom of an illness, such as diseases of the mouth cavity and nasopharynx (the area behind the nose and above the throat).
  • Bad breath can usually be eliminated with regular, thorough hygienic care of the mouth and teeth.
  • If bad breath is caused by an illness, this must be treated appropriately.

Note: The information in this article cannot and should not replace a medical consultation and must not be used for self-diagnosis or treatment.

A woman with a towel wrapped around her head coughs into her open hand to check her breath.

What is bad breath?

Bad breath – referred to by doctors as “halitosis” – describes a condition of having a strong, unpleasant smell of the breath, which is noticeable to other people. People with bad breath are often unaware of it.

A distinction is made between normal (physiological) bad breath, which is experienced by everyone, and disease-related (pathological) bad breath.

Bad breath can be avoided with regular and thorough mouth hygiene. However, if the bad breath is particularly noticeable and persistent, this may indicate that it is due to a disease of the mouth cavity.

In rare cases, certain diseases of the respiratory system and gastrointestinal tract or certain metabolic disorders may also cause bad breath.

What are the symptoms of bad breath?

Many people are unaware that they have bad breath and are often informed of the problem by people around them.

What causes bad breath?

The mouth is home to bacteria that digest food particles left on and between the teeth. These bacteria produce foul-smelling metabolic products, such as sulfurous gases that escape with exhaled air and are perceived by other people as bad breath.

People often have bad breath immediately after waking and this is considered normal. The reason for bad breath in this case is a relatively low flow of saliva in the mouth. This promotes the formation of plaque (a film of bacteria) on the teeth and tongue. Generally, all that’s needed to get rid of this “morning breath” is to brush the teeth, drink some water or eat some food to stimulate the flow of saliva again.

People often have bad breath in the morning immediately after waking. This is normal and no cause for concern.

Smoking cigarettes, drinking alcohol or eating strong-smelling foods such as garlic can also cause temporary bad breath.

If bad breath persists, this may indicate inadequate dental hygiene. For example, food particles can become lodged between the teeth in the absence of thorough brushing.

The following are also some common causes of persistent bad breath:

Sometimes, the cause may be abscesses in the nose and mouth, recurring tonsillitis or sinusitis (inflammation of the sinuses).

The following causes are rarer:

How is bad breath diagnosed?

Bad breath is perceived as a foul smell from the breath exhaled through the mouth and nose.

To pinpoint the cause of persistent bad breath, a doctor will ask about:

  • personal eating habits
  • daily oral and dental hygiene
  • pre-existing conditions and prior dental treatment
  • any medication the patient is taking

The doctor will also examine the oral (mouth) cavity, in particular the teeth, tongue and gums, as well as the throat, nasal cavities and upper airways.

It is also possible to measure the level of volatile metabolic products – such as sulfur compounds, for example – in the breath to support a diagnosis.

How is bad breath treated?

If a cause for the bad breath cannot be identified, making some lifestyle changes and improving mouth hygiene will usually help eliminate the problem.

These include:

  • chewing sugar-free gum to stimulate the flow of saliva and prevent bacteria from settling in the mouth
  • drinking plenty of fluids, ideally water
  • limiting intake of alcohol and coffee
  • cleaning the teeth thoroughly and, once a day, cleaning the spaces between the teeth
  • gently cleaning the tongue – in particular towards the back – with a tongue scraper or tongue brush
  • gargling regularly with mouthwash and rinsing the mouth – ideally before bedtime, as any residue from the mouthwash will remain in the mouth overnight and will have more time to take effect
The following tips may help with bad breath: chewing gum, drinking plenty of water, cutting down on alcohol and coffee and taking good care of the teeth and mouth.

Probiotics – preparations containing live microorganisms – may also help maintain a healthy balance of bacteria in the mouth.

If bad breath is caused by an illness, this must be treated appropriately. For example:

  • dental treatment of gingivitis, periodontitis or tooth decay
  • where possible, stopping medication that causes dry mouth

  • Deutsche Gesellschaft für Hals-Nasen-Ohren-Heilkunde, Kopf- und Hals-Chirurgie e.V. (DGHNO-KHC), Deutscher Berufsverband der Hals-Nasen-Ohrenärzte e.V., Deutsche Gesellschaft für Kinder- und Jugendmedizin e.V. (DGKJ), Deutsche Gesellschaft für Pädiatrische Infektiologie e.V. (DGPI). Therapie entzündlicher Erkrankungen der Gaumenmandeln – Tonsillitis. S2k-Leitlinie. AWMF-Registernummer 017/024. 08.2015.
  • DynaMed [Internet], Ipswich (MA). Halitosis. EBSCO Information Services. Record No. T114540. 2018 (1995). Aufgerufen am 30.07.2021.
  • UpToDate (Internet). Bad breath. Wolters Kluwer 2021. Aufgerufen am 30.07.2021.
  • UpToDate (Internet). Tonsillectomy in adults: Indications. Wolters Kluwer 2020. Aufgerufen am 30.07.2021.

In cooperation with the Institute for Quality and Efficiency in Health Care (Institut für Qualität und Wirtschaftlichkeit im Gesundheitswesen – IQWiG).

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