Bad breath, medically known as halitosis (Mundgeruch in German), affects approximately 25-30% of the population. In 85-90% of cases the cause lies in the mouth. The remaining 10-15% are linked to ENT conditions, gastrointestinal issues, or systemic diseases.
Causes: what happens inside the mouth
Tongue coating
The main culprit. The back third of the tongue harbours bacteria that produce volatile sulphur compounds (VSC), creating the characteristic smell.
Gum disease (periodontitis)
Deep periodontal pockets become bacterial reservoirs. The smell from periodontitis is persistent and cannot be removed by normal brushing.
Cavities and failing restorations
Decayed teeth and leaking fillings trap food debris and bacteria, creating an odour source that no mouthwash can reach.
Dry mouth (xerostomia)
Saliva is the mouth's natural rinse. When saliva flow drops (medications, mouth breathing, ageing), bacteria multiply faster.
Diagnosis at the dentist
Your dentist may use an organoleptic test (smelling breath at a set distance) or a halimeter that measures sulphur compound concentration.
If no dental cause is found, you may be referred to an ENT specialist (HNO-Arzt) or gastroenterologist.
What you can do right now
🪥 Clean your tongue every evening with a tongue scraper (Zungenreiniger)
🧵 Use floss or interdental brushes daily
💧 Drink enough water: dry mouth worsens the smell
🦷 Book a professional cleaning (PZR)
What does not help
Gum and mouthwash mask the smell for 15-30 minutes but do not eliminate the cause. Alcohol-based mouthwashes can make things worse by drying out the mucosa.
Self-testing by breathing into your hand is unreliable: the brain adapts to its own smell. Ask someone you trust for an honest opinion, or visit your dentist.