In short: Most chronic bad breath comes from bacteria in the mouth — especially on the back of the tongue and along the gumline — breaking down food and releasing smelly sulphur gases. Gum disease, dry mouth, tobacco and certain foods make it worse. In most cases, good cleaning and treating the underlying cause fixes it.
Persistent bad breath, or halitosis, is common and almost always has a treatable cause. The great majority of cases — around 85–90% — start in the mouth itself. Here’s why:
- Bacteria on the tongue. The rough back surface of the tongue traps food, dead cells and bacteria that release foul-smelling sulphur compounds. This is the single most common cause.
- Gum disease. Bacteria in inflamed gums and deep gum pockets produce a persistent bad odour.
- Trapped food and poor cleaning. Food stuck between teeth or around old fillings rots and smells.
- Dry mouth. Saliva cleans the mouth naturally. When it’s reduced — overnight, from certain medicines, dehydration, or mouth-breathing — odours build up. This is why “morning breath” happens.
- Tobacco and gutka, and strongly flavoured foods like onions and garlic.
Less commonly, bad breath comes from outside the mouth — sinus or throat infections, or certain medical conditions — but the mouth is by far the usual source.
What helps: brushing twice a day, cleaning your tongue (a tongue scraper works well), flossing daily, staying hydrated, and treating any gum disease. Mouthwash only masks odour temporarily — it’s not a cure.
If bad breath persists despite good cleaning, it’s worth a proper assessment. Our bad breath treatment finds and fixes the actual cause rather than just covering it up.