Medical Encyclopaedia › Bad breath (short definition)
In brief: Bad breath (halitosis) is an unpleasant odour of the exhaled air. It is widespread and can be very distressing in everyday life. In the vast majority of cases, the cause lies in the mouth itself, above all in coating on the back of the tongue and in gum inflammation. Dental practices are therefore usually the right first point of contact.
How does bad breath develop?
Bacteria in the mouth break down protein residues from food, saliva and dead cells. This produces volatile sulphur compounds that smell unpleasant. Particularly large numbers of these bacteria are found in the coating on the back of the tongue, in gum pockets, under leaky fillings, crowns or bridges and under poorly cleaned dentures. Morning breath after the night is normal, because little saliva flows during sleep, and disappears after breakfast and brushing the teeth.
Causes
- In the mouth: tongue coating, gum inflammation and periodontitis, caries, inflammation around wisdom teeth, inadequate cleaning of the spaces between teeth and of dentures, dry mouth, for example due to medicines, mouth breathing or drinking too little.
- In the ear, nose and throat area: chronic tonsillitis, tonsil stones, sinusitis.
- Temporary: garlic, onions, alcohol, smoking, fasting.
- Rare: general diseases such as poorly controlled diabetes, liver or kidney disease; these often cause a typical, different odour. Whether reflux plays a role has not been clearly established.
Diagnosis
Many people find it difficult to judge their own breath. Some perceive bad breath that is objectively not present (pseudo-halitosis or halitophobia). In the dental practice or a bad-breath clinic, the odour of the exhaled air is first assessed, sometimes supplemented by measuring devices for sulphur compounds. The tongue, teeth, gums, fillings and dentures are then examined. If no cause is found in the mouth, an ENT or GP assessment is advisable.
What helps?
- Tongue cleaning: clean the back of the tongue from back to front every day with a tongue scraper or tongue brush.
- Thorough oral hygiene: brush teeth twice a day with fluoride toothpaste, clean between the teeth daily with dental floss or interdental brushes, clean dentures carefully.
- Dental treatment of caries, leaky fillings and gum inflammation; in periodontitis, systematic periodontal therapy; professional tooth cleaning.
- Mouthwashes with antibacterial agents such as chlorhexidine or zinc compounds can help as an adjunct and for a limited time; with prolonged use, chlorhexidine can cause discoloration and taste changes.
- Drink enough, do not smoke, have medicines checked if you have a dry mouth.
Chewing gum, sprays and lozenges usually only mask the odour briefly.
Important to know
Persistent bad breath despite good oral hygiene should be investigated, as should accompanying bleeding gums, loose teeth, pain, fever, difficulty swallowing or an unusual odour, for example fruity or ammonia-like. Treatment of dental and gum diseases is generally covered by German statutory health insurance; professional tooth cleaning usually is not. If people suffer greatly from bad breath that is objectively not present, psychological support can be helpful.
Related terms in the encyclopaedia
Mouthwash, Tongue coating, Periodontitis, Gingivitis, Xerostomia, Interdental cleaning, Chlorhexidine, Professional tooth cleaning, Caries
Sources
- Seemann R et al.: Halitosis management by the general dental practitioner – results of an international consensus workshop. J Breath Res 2014
- AWMF-S3-Leitlinie Die Behandlung von Parodontitis Stadium I bis III (DG PARO, DGZMK)
- Gemeinsamer Bundesausschuss (G-BA): Richtlinie zur systematischen Behandlung von Parodontitis und anderer Parodontalerkrankungen (PAR-Richtlinie)
- Deutsche Gesellschaft für Zahn-, Mund- und Kieferheilkunde (DGZMK): Patienteninformationen zur Mundhygiene
Note: This article is for general information and does not replace advice, diagnosis or treatment from a doctor, dentist or pharmacist. Last updated: October 2026.