Bad breath that brushing doesn't fix

Persistent bad breath is one of the things people are most self-conscious about and least likely to raise at an appointment. It is also, in the large majority of cases, straightforwardly fixable.

Where it comes from

Around nine in ten cases originate in the mouth, not the stomach. Bacteria break down proteins and release volatile sulphur compounds — the same chemistry that makes rotten eggs smell. The question is where those bacteria are living.

• The back of the tongue. The single most common site. The surface is textured and holds a coating a toothbrush on the teeth never touches.
• Between the teeth. Brushing cleans about three of the five surfaces of each tooth. The two you miss are where plaque sits.
• Gum pockets. Periodontal disease creates deep spaces that harbour exactly the bacteria producing the worst odour.
• Decay and failing fillings — spaces that trap food and cannot be cleaned.
• Dry mouth. Saliva is the mouth's own cleaning system. Reduced flow — from medication, dehydration, long shifts, or breathing through the mouth at night — makes everything worse. It is why morning breath exists.

What to do, in order

• Clean your tongue. A scraper, or the back of your brush, front to back, twice a day. For many people this alone solves it.
• Clean between your teeth daily. Floss or interdental brushes. Not optional if this is your problem.
• Drink more water. Unglamorous and effective.
• Get the gums assessed. If they bleed, that is where the smell is coming from and no mouthwash will reach it.

What mouthwash actually does

Most mask odour for twenty minutes to an hour. Some contain alcohol, which dries the mouth and makes things worse across a day. Antibacterial rinses prescribed for a specific reason and a limited period are useful; a bottle used indefinitely to cover a problem is not treatment.

When it is not the mouth

If your mouth is genuinely clean, your gums are healthy and it persists, consider sinus and tonsil problems, reflux, uncontrolled diabetes, or medication causing dry mouth. A dentist can rule the mouth in or out, which is a useful first step before investigating anything else.

How to actually check your own breath

Cupping your hands over your mouth does not work — you stopped smelling your own breath long ago. Scrape the back of your tongue with a clean spoon, wait a few seconds, and smell that. It is unpleasant and it is honest.

General information only. It is not a substitute for an examination — book an appointment for advice about your own teeth.