Persistent bad breath, known clinically as halitosis, almost always begins in the mouth rather than the stomach. Bacteria break down food debris and proteins and release sulphur compounds, which are what produce the smell. That matters, because it tells you where to look for a solution — and why mouthwash alone rarely provides one.
The back of the tongue is the usual culprit
The rough surface at the back of the tongue traps bacteria, dead cells and food debris in a coating that is remarkably good at producing sulphur compounds. It is also the area most people never clean. Brushing teeth thoroughly while ignoring the tongue leaves the main source untouched, which is why so many people feel they are doing everything right and still have a problem.
Clean the tongue daily with a tongue scraper or the back of your toothbrush, working from as far back as you can comfortably reach and drawing forwards. It takes a few seconds and it is frequently the single most effective change people make.
Gum disease and the spaces between teeth
The second major source is bacteria between the teeth and below the gumline. Gum disease creates deeper pockets around the teeth where bacteria thrive out of reach of a toothbrush, and the smell that produces is distinctive. Bleeding gums alongside bad breath is a strong indication that gum disease is involved.
Brushing cleans roughly three of the five surfaces of each tooth; the two between teeth need floss or interdental brushes. If bad breath has persisted despite good brushing, cleaning between the teeth is usually the missing piece. Our guides to flossing correctly and spotting gum disease early both go into more detail.
Dry mouth makes everything worse
Saliva is the mouth's natural cleaning system: it washes away debris and neutralises the compounds that cause odour. When saliva flow drops, bacteria multiply and the smell intensifies. This is exactly why morning breath exists — saliva production falls overnight.
Persistent dry mouth is a common side effect of many prescription medicines, and it also follows from mouth breathing, snoring, alcohol and dehydration. If your mouth is regularly dry, treating that will do more for your breath than any mouthwash.
Other dental causes worth ruling out
Decay, which creates cavities that trap food and bacteria
Old or broken-down fillings with gaps at the edges
Dentures that are not cleaned thoroughly or are worn overnight
Partly erupted wisdom teeth, where a gum flap traps debris
An abscess or long-standing infection
Each of these is straightforward to identify at an examination, and none will resolve on its own.
Why mouthwash disappoints
Most mouthwashes mask odour with mint for twenty minutes or so without touching the cause. Worse, strongly alcohol-based rinses dry the mouth, which can make the underlying problem slightly worse over time. If you want to use a rinse, choose an alcohol-free one, and treat it as an extra rather than a substitute for cleaning.
One practical point often missed: rinsing with water immediately after brushing washes away the concentrated fluoride left on your teeth. Spit, do not rinse.
What to do, in order
Clean your tongue daily, right at the back where the coating sits
Clean between every tooth once a day with floss or interdental brushes
Brush twice daily with fluoride toothpaste and spit rather than rinse
Drink water regularly and treat dry mouth if it is persistent
Book a scale and polish to remove tartar you cannot shift at home, from £70 with a hygienist
Have any decay, failing fillings or gum problems assessed and treated
If bad breath persists after all of the above and your mouth has been given a clean bill of health, it is worth speaking to your GP. A small proportion of cases relate to sinus, tonsil, reflux or other medical causes, and those need investigating elsewhere. But the mouth is where to start, because that is where the answer usually is.
If bad breath is bothering you, a hygiene appointment and examination will identify the cause. See our general dentistry services or call our Burton Joyce practice on 0115 931 2935. It is a common problem and one we discuss without any awkwardness.
FAQ
Q: What causes bad breath? A: Around nine in ten cases start in the mouth, most often from bacteria coating the back of the tongue, plaque between the teeth, gum disease, decay or dry mouth.
Q: Why does my breath smell even though I brush twice a day? A: Brushing cleans only about three of the five surfaces of each tooth and does not clean the tongue. The back of the tongue and the gaps between teeth are the two areas most commonly missed.
Q: Does mouthwash cure bad breath? A: No. It masks odour temporarily without addressing the cause, and alcohol-based rinses can dry the mouth and make things slightly worse. Use an alcohol-free rinse as an extra, not a substitute.
Q: Can bad breath come from the stomach? A: Rarely. Most cases are oral in origin. If your mouth is healthy and the problem persists, speak to your GP about sinus, tonsil or reflux causes.
Q: How do I clean my tongue properly? A: Use a tongue scraper or the back of your toothbrush, starting as far back as is comfortable and drawing forwards. Do this once daily; it is often the single most effective change.